Radio Systems at 60GHz and Above
RADIO COMMUNICATIONS RESEARCH UNIT
CCLRC RUTHERFORD APPLETON LABORATORY
Radio Systems at 60GHz and Above
Ofcom Contract 410000258
Radio Communications Research Unit
Rutherford Appleton Laboratory
Chilton, Didcot
Oxfordshire OX11 0QX
Tel: +44 (0) 1235 445622
Fax: +44 (0) 1235 446140
Web: http://www.rcru.rl.ac.uk/
S.Ventouras , S.A. Callaghan - CCLRC Rutherford Appleton Laboratory
I.Clark, A.Burges, G.Porter - OciusB2
J.R.Norbury - Satconsult Ltd
S.M. Feeny, S.Salous - The University of Durham
February 2006
Radio Systems at 60GHz and Above
Table of Contents
SUMMARY ................................................................................................................................................ 5
1
INTRODUCTION ........................................................................................................................... 12
2
EXAMINATION OF SYSTEM APPLICATIONS IN THE BANDS 60 – 100 GHZ ................. 14
2.1 INTRODUCTION ..................................................................................................................... 14
2.1.1
Choice of RF parameters ................................................................................................... 14
2.1.2
Meteorological parameters................................................................................................ 15
2.1.3
Communications system parameters.................................................................................. 16
2.1.4
Typical performance of a line of sight system on a 4km path ............................................ 16
2.2 EVALUATION OF SYSTEM PERFORMANCE FOR SEVERAL POTENTIAL
APPLICATIONS ................................................................................................................................. 17
2.2.1
Line of sight (LOS) systems................................................................................................ 17
2.2.2
Free space Optical systems................................................................................................ 20
2.2.3
Giga bit/s Wireless LAN..................................................................................................... 20
2.2.4
Broadband fixed wireless access ....................................................................................... 22
2.2.5
Satellite communications and high altitude platform systems ........................................... 24
2.2.6
Mobile systems communications and short range repeaters for back haul ....................... 29
2.2.7
Personal communications and home networks .................................................................. 31
2.3 CONCLUSIONS........................................................................................................................ 34
2.4 REFERENCES .......................................................................................................................... 36
3
IDENTIFICATION OF KEY OBSTACLES TO BAND USE..................................................... 37
3.1 INTRODUCTION ..................................................................................................................... 37
3.2 TRANSMITTER TECHNOLOGY.......................................................................................... 37
3.2.1
Classical solutions ............................................................................................................. 37
Available Transmit Power ................................................................................................................. 45
3.2.2
Recent Transmitter technology for 60-100GHz ................................................................. 46
3.3 RECEIVER TECHNOLOGY .................................................................................................. 48
3.3.1
Classical Solutions............................................................................................................. 48
3.3.2
Recent Receiver technology for 60-100GHz ...................................................................... 52
3.4 COST OF TECHNOLOGY ...................................................................................................... 53
3.5 CONCLUSIONS........................................................................................................................ 54
3.6 REFERENCES .......................................................................................................................... 54
4 IMPLICATIONS OF LICENSED AND LICENCE-EXEMPT USE & A SYRVEY OF
INTERNATIONAL ACTIVITY IN BANDS 60-100 GHZ .................................................................. 55
4.1 INTRODUCTION ..................................................................................................................... 55
4.2 CURRENT UK POSITION ...................................................................................................... 55
4.3 SURVEY..................................................................................................................................... 59
4.3.1
Process............................................................................................................................... 59
4.3.2
European National Regulators .......................................................................................... 59
4.3.3
Non-European National Regulators .................................................................................. 62
4.3.4
IEEE................................................................................................................................... 64
4.3.5
Industry .............................................................................................................................. 64
4.4 DISCUSSION............................................................................................................................. 67
4.5 CONCLUSIONS AND RECOMMENDATIONS ................................................................... 69
4.5.1
Market readiness and applications .................................................................................... 69
4.5.2
Technical regulatory parameters....................................................................................... 69
4.5.3
Operating frequencies........................................................................................................ 71
4.5.4
Licensing............................................................................................................................ 71
4.5.5
Further Work ..................................................................................................................... 71
2
Radio Systems at 60GHz and Above
ANNEX 1: INITIAL QUESTIONNAIRE ............................................................................................. 73
ANNEX 2 :TARGET RECIPIENTS OF INITIAL QUESTIONNAIRE............................................ 74
ANNEX 3: FURTHER DISTRIBUTION OF INITIAL QUESTIONNAIRE .................................... 76
ANNEX 4: SECOND STAGE QUESTIONNAIRES............................................................................ 77
ANNEX 5: REGULATORS FOR POSSIBLE FURTHER WORK.................................................... 82
ANNEX 6: UNITED KINGDOM FREQUENCY ALLOCATION TABLE 2004 ............................. 85
ANNEX 7: DRAFT ECC DOCUMENT ECC/REC/(05)07.................................................................. 90
A.
CALCULATED PARAMETERS ACCORDING TO ITU-R REC. 746 ...................................................... 94
B. ............................................................................................................................................................ 94
ANNEX 8: ECC DOCUMENT ECC/REC/(05)02 ............................................................................... 99
ANNEX 9: RESPONSES TO SURVEYS - REGULATORS ............................................................. 104
ANNEX 10: RESPONSES TO SURVEYS - INDUSTRY .................................................................. 115
5
RADIO CHANNEL CHARACTERISATION............................................................................ 120
5.1
5.2
5.3
5.4
5.5
INTRODUCTION ................................................................................................................... 120
DURHAM 60 GHZ CHANNEL SOUNDER.......................................................................... 120
CHANNEL SOUNDER CALIBRATION AND VERIFICATION...................................... 121
RESULTS OF CHANNEL SOUNDINGS ............................................................................. 122
CONCLUSIONS ........................................................................................................................... 123
ANNEX 1: CHANNEL SOUNDING MEASUREMENTS IN THE DURHAM SCHOOL OF
ENGINEERING. ................................................................................................................................... 125
ANNEX 2: DESCRIPTION OF THE CHANNEL SOUNDER TRANSMIT AND RECEIVE
HARDWARE DEVELOPED TO SUPPORT THE PROJECT. ....................................................... 139
6
THE SPECTRUM EFFICIENCY OF FREQUENCY/POWER CONTROL .......................... 152
6.1 ATPC (ADAPTIVE TRANSMIT POWER CONTROL)....................................................................... 152
6.1.1
ATPC operation ............................................................................................................... 152
6.1.2
Previous studies ............................................................................................................... 154
6.2 DFD (DYNAMIC FREQUENCY DIVERSITY) ................................................................................. 155
6.2.1
DFD operation................................................................................................................. 155
6.3 RAIN FIELD CORRELATION ................................................................................................ 155
6.3.1
Spatial and temporal analysis of meteorological radar data: Data description.............. 156
6.3.2
Spatial autocorrelation of measured rain fields............................................................... 156
6.3.3
Exponential rain model.................................................................................................... 161
6.4 LINK TOPOLOGIES ............................................................................................................. 162
6.5 SPECTRUM EFFICIENCY GAINS RESULTING FROM IMPLEMENTING ATPC.... 169
6.6 SPECTRUM EFFICIENCY GAINS RESULTING FROM IMPLEMENTING DFD ...... 169
6.7 REFERENCES ........................................................................................................................ 170
7
DUAL MILLIMETRE WAVE/FSO SYSTEMS......................................................................... 171
7.1
7.2
7.3
8
INTRODUCTION ................................................................................................................... 171
RESULTS................................................................................................................................. 171
CONCLUSIONS...................................................................................................................... 177
DEMONSTRATION AND OPERATIONAL TRIALS OF WORKING SYSTEMS.............. 178
8.1 INTRODUCTION ................................................................................................................... 178
8.2 TRIAL SITE AND INSTALLATION.................................................................................... 178
8.2.1
Location ........................................................................................................................... 178
8.2.2
Installation ....................................................................................................................... 180
8.3 DEPLOYED EQUIPMENT AND INSTALLATION........................................................... 181
3
Radio Systems at 60GHz and Above
8.3.1
System configuration........................................................................................................ 181
8.3.2
64GHz link equipment...................................................................................................... 182
8.3.3
Free space optical equipment .......................................................................................... 183
8.3.4
Network monitoring and alarms ...................................................................................... 184
8.3.5
Weather monitoring ......................................................................................................... 185
8.4 SYSTEM PERFORMANCE .................................................................................................. 187
8.5 ECONOMICS OF DEPLOYEMENT.................................................................................... 189
8.6 TRIAL CONCLUSIONS AND FURTHER WORK ............................................................. 190
9
CONCLUSIONS AND RECOMMENDATIONS ....................................................................... 191
4
Radio Systems at 60GHz and Above
SUMMARY
Introduction
This is the final report for a study for OFCOM to investigate the current state and future
bands above 60 GHz in terms of devices, systems, applications, sharing and regulations.
The utilisation of spectrum is leading to the need to consider higher frequency
communication systems, including those in the millimetre-wave band. Greater use of
the bands above 60 GHz could provide a useful increase in the spectrum available and
could also release spectrum at lower frequencies for other purposes. The 60 GHz band,
in particular, is well suited as it combines the potential for large information bandwidths
with highly efficient frequency reuse due to the natural isolation offered by the oxygen
absorption band. This makes it possible to reuse the same spectrum enabling closely
spaced adjacent systems. However, as these frequency bands suffer severely from rain
attenuation, their usefulness on their own for outdoor systems may be limited.
Applications that have been considered for these bands are short fixed links, high data
rate links between buildings, broadband last mile applications, aircraft links, indoor
WLAN, telematics (e.g. vehicle-to-vehicle, advanced vehicle control, co-operative
driving, vehicle to roadside and safety systems), personal broadband applications, etc.
An attraction of exploiting these high frequencies is not only the potential availability of
high bandwidth systems but also the availability of small scale technology that could be
used to reduce size and weight of the applications developed.
This study was decomposed into two threads.
•
Theoretical studies and literature searches
The major goal was to map out the current state and future of bands above 60
GHz in terms of devices, systems, applications, sharing and regulation.
•
Operation of real systems
A commercial system using the 60GHz band was operated in an industrial
environment in conjunction with a FSO (Free Space Optical) link.
In addition several years’ of frequency diverse experimental data ( at 57, 97,
135, and 210 GHz and data from a FSO link) was analysed to provide base-line
operational data. The data collected on the 500 m range at Chilbolton, UK
during the period April 1991 to September 1995
5
Radio Systems at 60GHz and Above
Objectives
The scope of the work covered was to investigate the following topics:
1) Examination of System Applications in the Bands 60-100GHz
A number of typical applications for millimetre wave communications systems have
been examined and their performance evaluated in adverse weather conditions (rain, fog
and turbulence), where applicable. These applications included:
o
o
o
o
o
o
o
o
o
o
o
Line of sight point to point links (LOS)
Free space optical systems (FSO) (for comparison)
Giga bit/s Wireless LAN
Broadband fixed wireless access (BFWA)
Satellite communications (Satcom)
Aero satellite communications (Aerosat)
High altitude platform systems (HAPS)
Mobile systems
Short range repeaters for network backhaul
Personal communications
Home communications
2) Identification of key obstacles to band use
Study into device technologies at millimetre and sub-millimetre wavelengths,
particularly for airborne and space based applications.
Unlike lower frequencies, semiconductor integrated circuits do not provide the complete
answer at millimetre waves. Significant amount of the product size and cost consists of
passive components based on waveguide structures, used for implementing and
enclosing filters, diplexers, gain stages and interconnects. This complex of plumbing
must be replaced by a technology that can scale down in cost as market size and
applications expand. The radio link must evolve in cost effectiveness in a manner
similar to the cellular phone, the PC and digital cameras. New architectures must be
developed with a low-cost appliance-design mindset.
3) Implications of Licensed and Licensed-Exempt Use & A survey of International
Activity in Bands 60-100 GHz
An international survey has been conducted into regulation, systems and applications of
frequency bands specified by the ITU-R for telecommunications use. The objective of
the survey was to determine how the higher frequency bands would be utilised in
various licensing scenarios (e.g. no, light touch and fully managed licensing). In
support of this, national regulators, voluntary standardisation bodies and commercial
organisations have been approached.
The main bands of interest internationally are 60-61, 64-66, and 71-76/81-86 GHz.
6
Radio Systems at 60GHz and Above
4) Radio Channel Characterisation
Channel sounders are used to evaluate the typical delay spread in a range of
environments where high frequency wireless connections may be used e.g. mobile
telecoms and WLAN applications. The distribution of delays is determined by the
multi-path scattering environment e.g. reflections off the ground, buildings and internal
walls within buildings.
Durham University have developed radio channel sounders based upon FMCW
techniques. Data processing algorithms have also been developed to extract information
about the channel from the measured data. The work to date has been addressing
frequencies up to 6GHz.
This work package included the provision of the frequency extension modules for the
existing channel sounder, integration and calibration of the sounder at the new bands,
channel measurements in a variety of configurations and manipulation of data to
provide results.
A series of measurements were made characterising typical indoor-indoor and outdoorindoor propagation paths. Measurements were made using a range of commercial and
academic buildings, built of a range of materials, and being put to a range of uses.
Limited outdoor mobile measurements around the campus of the University were also
carried out.
5) The spectrum Efficiency of Frequency/Power Control
Examination of rain scatter and ATPC for heterogeneous networks using sophisticated
rain scatter and rain field models
Adaptive Transmit Power Control (ATPC) has been proposed in the literature as a
promising technique for opening up higher frequencies to commercial exploitation. It
can also be used at lower frequencies to reduce the transmit power used during clear sky
conditions and compensating for fading on a dB by dB basis. This would enable an
increase in the rate of frequency re-use, and hence an improved spectral efficiency.
Radio systems operating at 60GHz and above are not currently efficient or economical
due to the large fade margins required to compensate for the intermittent yet dramatic
effects of rain fading. ATPC and Dynamic Frequency Diversity (DFD), are fade
mitigation techniques which can help to make systems at these frequencies more
economical, and hence more open to commercial exploitation.
6) Dual Millimetre Wave/FSO systems.
Frequency bands above 60 GHz suffer severely from rain attenuation. This will put
constraints upon the length or availability of links. Free Space Optical (FSO) systems
are similarly affected by the presence of fog and mist and suffer even lower
availabilities. However, it is speculated that heavy rain and fog/mist rarely occur
7
Radio Systems at 60GHz and Above
simultaneously. Therefore, frequency diverse systems, combining mm-wave and Free
Space Optical (FSO) systems, have the potential to provide very high availability with
reduced interference.
The joint statistics of operation of the mm-wave link in combination with the FSO link
were studied.
Demonstration and Operational Trials of Working systems
The purpose of the Demonstration and Operational Trial was to verify the availability,
reliability and performance of millimetre-wave radio equipment in routine production
and to consider its economic viability deployed in a commercial environment. For
comparative purposes, an FSO link equipment was also deployed in a dual
configuration on a parallel path.
OciusB2 hosted the trial at their site in Runcorn, Cheshire; the equipment was
commissioned to provide links between the main site and a business park at The Heath.
OciusB2 transmitted commercial traffic across both the 64GHz link and the FSO link.
Installation and deployment were completed by March 2005 and the operational
performance of the links was continuously monitored for system parameter errors and
failures through to November 2005.
The trial also enabled a typical set of deployment costings to be generated, and dual
mm-wave/FSO link to be bench-marked against other technologies and deployment
options for short-range high data applications.
Conclusions and Recommendations
The following conclusions were drawn:
Examination of System Applications in the Bands 60-100 GHz & Identification of Key
Obstacles to Band Use
Millimetre wave communications systems at frequencies above 60 GHz have the
potential for very high capacities, especially as more than 10 GHz of bandwidth is
available in the current frequency allocations.
Spectrum that is not subject to the oxygen absorption effect exhibits behaviour which is
broadly similar to spectrum below 60GHz where, in the absence of precipitation fading,
the limit of propagation is the horizon.
Specific applications have been identified that require broad contiguous blocks of
spectrum e.g. radio transmission of gigabit ethernet services.
Millimetre wave communications applications need to operate over short paths (<
10km) and also need to take advantage of the high antenna gains and directivities,
which can be achieved with small antenna sizes (typically 10 < diameter < 30cms).
8
Radio Systems at 60GHz and Above
Two applications have been identified for further study. These are:
a. Wireless local area networks providing ~1Gbps capacity through
millimetre wave access points.
b. Very high capacity backhaul for either MESH or branch and tree
networks, operated in conjunction with very local wireless distribution
services at lower frequencies.
The exploitation of these bands requires the development of low-cost RF technology.
At the frequency range 60 – 100 GHz transmitter/receiver
mature and mass-produced systems are commercially
transmitters with 10mW output power and receivers with
available today to fulfil the radio link requirements for the
section 2. .
technology is reasonably
available. For example
10dB Noise Figure are
applications presented in
Millimetre wave systems are not particularly suited to situations where long range is
required e.g. satellite or HAPS systems or where non-line of sight paths are experienced
(e.g. personal communications and home networks).
Millimetre wave systems, at ranges of more than 100m, provide a much better quality of
service, in adverse weather conditions (rain and fog), than free space optical (infra red)
systems.
Implications of Licensed and Licence-Exempt Use & A survey of International Activity
in Bands 60-100 GHz
Manufacturers are now launching useable product, especially near the oxygen peak at
60GHz. These products exploit USA-FCC rules and provide a range of typically 1km.
There is also some activity at higher frequencies with longer range but manufacturers
are waiting for orders before committing to production tooling.
European and other regulators are starting to respond, although the response is far from
uniform, e.g. between Europe, USA, and ROW. Within Europe some regulators are
establishing national regimes, but most have waited for the report of SE-19. There is
still a preponderance of formal licensing, but some regulators will adopt a mix of
unlicensed and lightly licensed processes.
The bands 59-66 GHz : 71-76 GHz : 81-86 GHz should be opened on a lightly licensed
basis so as to satisfy growing demand.
‘Light licensing’ should be adopted. Traditional spectrum auctions have resulted in the
bands at 3,5GHz, 10,5GHz and 28GHz being privately owned but not deployed, and noone from manufacturing or operating industry has made a case for using the same failed
mechanisms in the new bands. Nevertheless, QoS requirements for the identified
applications require a degree of interference management. This could best be achieved
by following the new USA, low-cost, web-based registration scheme.
9
Radio Systems at 60GHz and Above
Due to the nature of the applications and the directivity of operational equipment in this
band, there should be no restriction on channel size. 10GB/s radio links would require
the full 5GHz spectrum.
In order to obtain the QoS required for the delivery of the identified applications, the
power levels given in tables A4.2 and A4.3 of the Draft ECC Document
ECC/REC/(05)07 ‘Radio Frequency Channel Arrangements for Fixed Service
System’ should be increased. Suitable limits for power at the antenna port for 1Gb in
both the 71-76GHz and 81-86GHz bands are 19dBm for FSK links, and 16QAM links.
There should be no modulation requirements or restrictions. It is believed that
BPSK/QPSK will be used in the majority of links due to the link length requirements
TPC should not be mandatory.
Ofcom should maintain an ongoing interest in the development of a Europe-wide
regulatory regime in the frequency bands between 60 and 100GHz that is sympathetic to
the needs of both operators and manufacturers; and that the development of both
regulations and market be continuously monitored throughout 2006.
Radio Channel Characterisation
Subject to the use of appropriate directional antennae line of sight paths operated with
low levels of multi-path components both in building and out of building.
Operation through glass was demonstrated with little degradation in multi-path
behaviour particularly for near normal incidence. Some smooth frequency selective
behaviour was observable across the frequency band measured.
Non line of sight propagation was observed to result in a wide spread of delay
components of near equal amplitude within a single corridor.
Non line of sight propagation around an obstacle was observed to occur at discreet
frequencies across the band measured only. At other frequencies transmission was
attenuated.
For outdoor links the strong reflection from adjacent structures must be considered
when selecting the antennae and the location of the terminal equipment.
The spectrum Efficiency of Frequency/Power Control & Dual Millimetre Wave/FSO
systems
Previous studies have investigated the spectrum efficiency benefits of implementing
ATPC in bands up to 38 GHz, primarily concentrating on fixed terrestrial links. In
higher frequency bands the situation is complicated by the 10GHz band around 60 GHz,
where the oxygen absorption band suppresses long distance transmissions, hence
10
Radio Systems at 60GHz and Above
enabling a reduction of the frequency reuse distance to as little as 1 km in some
situations.
The link layout scenario presented in this report is by necessity simplistic, dealing as it
does with only two links and a simplified rain model. Still the results suggest that ATPC
has the potential to improve spectrum efficiency in bands above 60GHz. As a worse
W/U is predicted in clear sky than in rain, designing a link to clear sky specifications
and compensating for rain fading dynamically on a dB by dB basis will minimise the
separation distance between the links.
Frequency bands above 60GHz suffer severely from rain. (Frequencies around 60GHz
suffer also from oxygen attenuation which in contrast with rain attenuation is always
present). Free Space Optical (FSO) systems are similarly affected by the presence of
fog and mist and suffer even lower availabilities. However the study of the joint
statistics between a microwave and optical link indicates that the deep fading at the two
frequencies did not occur simultaneously. This verifies the potential significant increase
in availability possible with the dual frequency configuration.
From measurements made at Chilbolton on the 500m range to achieve an availability of
99.99% on a FSO link, a fade margin of over 40 dB is required. For a radio link at 57
GHz, a fade margin of ~10 dB would be needed for the same availability. A combined
system using both a FSO link and a radio link at 57 GHz would require a 2 dB fade
margin on the radio link and a 10 dB fade margin for the FSO link, which is a
substantial reduction.
As with ATPC, reducing the transmit power of a radio link during clear sky conditions
will improve the rate of frequency reuse within a given geographical area. At this time,
effective and economic utilisation of the bands above 60 GHz is believed to be a higher
priority, as these frequencies are not commonly used.
Demonstration and Operational Trials of Working Systems
Both the 64GHz radio link and the FSO link have operated well with no reported link
failures over the installed distance of 450m.
An operational range of up to 1km for wide bandwidth connectivity using 60GHz radio
is practical. Installation is simple and rapid, and suitable equipment is commercially
available. Such links would appear to have multiple applications in campus networking
and ‘last mile’ environments.
11
Radio Systems at 60GHz and Above
1
INTRODUCTION
This Report investigates the current state and future bands above 60 GHz in terms of
devices, systems, applications, sharing and regulations. This study has examined the
constraints imposed by propagation conditions and the operational behaviour of
commercial millimetre-wave and FSO links. In addition several years’ of existing data
from at least four such dual links have been analysed to provide base-line operational
data.
In section 2 a wide range of applications for millimetre wave communications systems
have been examined and their performance evaluated in adverse weather conditions
(rain, fog and turbulence), where applicable.
The principal difficulty restricting the use of bands above 60 GHz for point-to-point
telecommunications links is the device constraints on radiated power: high power
devices are expensive, delicate or unavailable. A study which identifies the key
obstacles to the use of frequency bands above 60GHz is presented in section 3.
The way the higher frequency bands would be utilised in various licensing scenarios is
determined in section 4. In this section is also presented a survey of the regulation,
systems, and applications of frequency bands specified by the ITU-R for
telecommunications use, internationally. The surveying also includes commercial and
academic activity in these bands.
Channels sounders are used to evaluate the typical delay spread in a range of
environments where high frequency wireless connections may be used e.g. mobile
telecoms and WLAN applications. A description of a channel sounder developed by
Durham University is given in section 5.
A theoretical study to quantify the benefits of ATCP (Adaptive Transmit Power
Control) and DFD (Dynamic Frequency Diversity) on typical short link configurations
in frequency bands above 60 GHz is presented in section 6. These studies quantify
interfere power in a range of meteorological conditions and calculate typical reuse
distances for a range of availabilities.
Frequency bands above 60 GHz suffer severely from rain attenuation. This will put
constraints upon the length or availability of links. Free Space Optical (FSO) systems
12
Radio Systems at 60GHz and Above
are similarly affected by the presence of fog and mist and suffer even lower
availabilities. However, it is speculated that heavy rain and fog/mist rarely occur
simultaneously. Therefore, frequency diverse systems, combining mm-wave and Free
Space Optical (FSO) systems, have the potential to provide very high availability with
reduced interference. In section 7 we present the analysis of the data collected on the
500 m range at Chilbolton, during the period April 1991 to September 1995.
Operating trials and a working demonstration of the use of a 60GHz system in an
industrial environment in conjunction with a FSO link are described in section 8.
13
Radio Systems at 60GHz and Above
2
EXAMINATION OF SYSTEM APPLICATIONS IN THE BANDS
60 – 100 GHz
2.1 INTRODUCTION
A number of typical applications for millimetre wave communications systems have
been examined and their performance evaluated in adverse weather conditions (rain, fog
and turbulence), where applicable. These applications included:
•
•
•
•
•
•
•
•
•
•
•
Line of sight point to point links (LOS)
Free space optical systems (FSO) (for comparison)
Giga bit/s Wireless LAN
Broadband fixed wireless access (BFWA)
Satellite communications (Satcom)
Aero satellite communications (Aerosat)
High altitude platform systems (HAPS)
Mobile systems
Short range repeaters for network backhaul
Personal communications
Home communications
2.1.1 Choice of RF parameters
A number of assumptions were made concerning the values of the RF parameters for
these systems. The important characteristics, which are used in link budget calculations,
are antenna sizes, RF power levels of the transmitters, insertion losses of wave guide
connections and noise figures of the receivers. As the appropriate power levels, noise
figures and insertion losses are reasonably well known at 40 GHz through earlier studies
(e.g. The European Consortium studies (FP4 CRABS [1] & FP5 EMBRACE [2]
projects), these were used as an initial reference point at ~ 40 GHz. Equivalent values at
100 GHz, used in an earlier Radiocommunications Agency study [3] “ A study into the
theoretical appraisal of the highest usable frequencies” (AY4329), were chosen for the
upper frequency (100 GHz) point. A linear interpolation between these upper and lower
limits was used to derive the values for available RF power levels (figure 2.1a) and for
noise figures and insertion losses (Figure 2.1b) for the subsequent performance
evaluations. A background noise temperature of 2800K has been assumed to calculate
the overall system noise level.
Although peak power levels above 100mw might be technologically possible, the use of
such high powers in the millimetre band might not be the most cost effective solution.
Lower RF powers combined with larger antennas would be a better compromise. In
most of the applications discussed below, an RF power level some 10 dB below the
peak level has been used to evaluate the subsequent link budgets. The RF power versus
frequency relationship for these lower RF powers is shown in the yellow line in figure
14
Radio Systems at 60GHz and Above
2.1a. Applications which require higher power levels are discussed in the appropriate
section.
Antenna sizes, which vary depending on the application, range from very small (~ 1 cm
for indoor applications to 2m for satellite systems). In general, the antenna sizes used
have been limited to the smallest practical sizes required to achieve an adequate margin.
2.1.2 Meteorological parameters
Gaseous specific attenuation levels (appropriate to the band 40 to 100 GHz) were
obtained from ITU-R P676-5 [4] in 0.5 GHz intervals. Values of specific attenuation at
the peaks of any absorption line were also included as additional information. The
preliminary rain attenuation values at 0.01% and 0.1%, which were derived from ITU-R
P530 [5](and ITU-R P618 [6] for slant path systems), were estimated from values for
conditions relevant to London. Fog and scintillation values were also taken from
attenuation values quoted in this same report [5]. The fog densities chosen were
equivalent to an optical visibility of ~200m, which persists in the UK from between 1%
and 2% of the time, depending on the location. Is should be noted that the fog data used
in this MET. Office study [7] relates to conditions in the 1970s, where pollution levels
could well have been higher than those experienced in the 21st century. The scintillation
levels are derived from turbulence levels which exist for ~ 0.01% of the time
power level (dBm)
RF power vs frequency
30
25
realistic
RF power
20
15
10
maximum
RF power
5
0
40
60
80
100
frequency (GHz)
Figure 2.1a: Values of maximum and realistic RF power
15
Radio Systems at 60GHz and Above
feed losses & noise figures vs
frequency
value (dB)
5
feed loss
(dB)
4
3
2
noise
figure
(dB)
1
0
40
60
80
100
frequency (GHz)
Figure 2.1b: Values of feed losses and noise figures over the frequency range 40 to 100
GHz
2.1.3 Communications system parameters
The various parameters (link length, data rate, C/N, etc) used for the subsequent system
performance evaluation are shown in an associated table together with an accompanying
plot of system margin as a function of frequency. It is assumed that these hypothetical
communications systems operate in QPSK modulation mode and require a C/N =11dB
to achieve a bit error ratio (BER) of ~ 1 in 104. (This uncoded BER should be sufficient
to achieve an error free channel performance, when operated in conjunction with both
forward error correction and block error coding.)
2.1.4 Typical performance of a line of sight system on a 4km path
As an example Figure 2.2a shows the clear air margin (dark blue) achieved for of a line
of sight system on a 4km path operating with a data rate in excess of 100 Mbps. The
clear air margin (blue) is shown together with the reduced margins in rain, scintillation
conditions and fog for the specified availabilities.. The parameters, which were used to
evaluate the performance, are listed in table 1. It is clear that this system could achieve
16
Radio Systems at 60GHz and Above
reliability better than 99.99 % of the time over most of the frequency range, except in
the regions of the 60 GHz oxygen absorption line (54 to 68 GHz). Rain is the dominant
effect in determining the system performance with both fog and turbulence having
relatively minor effects.
margins for various meteorological conditions
on a 4 km path
50
clear air
margin
margin (dB)
40
fog margin at
200m visibility
30
20
scintillations
margin
99.99%
10
rain margin for
99.99% time
0
rain margin for
99.9% time
-10
40
60
80
100
frequency (GHz)
Figure 2.2a: Performance of LOS applications
2.2 EVALUATION OF SYSTEM PERFORMANCE FOR SEVERAL
POTENTIAL APPLICATIONS
2.2.1
Line of sight (LOS) systems
Performance has been estimated for typical point-to-point application over link lengths
from 2 to 16 km. The margins achieved in rain for 99.99% and 99.9% availabilities are
shown for the various path lengths in figure 2.2b and 2.2c, respectively. The effect on
performance of the oxygen absorption band around 60 GHz is clearly demonstrated,
where link lengths of > 2 km become impractical in the 55 to 65 GHz region. Rain
attenuation becomes important for links longer than 4 km outside the 60 GHz
absorption band. Although an 8 km LOS systems just achieves 99.99% availability at
40 GHz, the combined rain and gaseous attenuation above this frequency prevent this
level of availability. Data rates of 150 Mbps would be achieved with QPSK modulation
within the 100 MHz system bandwidth.
17
Radio Systems at 60GHz and Above
link length
2 to 16
transmitter antenna diameter
0.35
Transmitter power level 60/100 GHz
16/10
receiver antenna diameter
0.35
receiver bandwidth
100
C/N Margin for error free channel QPSK 11
(BER of 1 in 10^4) with additional coding
rain rate for 0.01%
22
km
m
dBm
m
MHz
dB
fog visibility
m
200
mm/h
Table 2.1: parameters for LOS systems
rain margins for several path
lengths at 99.99% availability
margin (dB)
40
30
2 km
20
4 km
10
0
8 km
-10
40
60
80
100
frequency (GHz)
Figure 2.2b: Performance of LOS applications for several path lengths at 99.99%
availability
18
Radio Systems at 60GHz and Above
rain margins for several path
lengths at 99.9% availability
margin (dB)
40
2 km
4 km
8 km
16 km
20
0
40
60
80
100
frequency (GHz)
Figure 2.2c:Performance of LOS applications for several path lengths at 99.9%
availability
19
Radio Systems at 60GHz and Above
2.2.2 Free space Optical systems
The performance values for the FSO system were extracted from the Terabeam data
sheet (Avara™ 4221e Specifications), as this was the system purchased for the trial
conducted in this project. The clear air margin has been plotted in figure 2.3, as a
function of path length, together with the reduced margins achieved in rain (99.99%
availability), fog (200m visibility) and scintillations (99.99% availability). The
meteorological values are those appropriate to London and would differ slightly from
those prevailing at the trial site at Runcorn. In particular the rainfall rate appropriate to
0.01% is ~25 mm/h and the 200 m visibility occurrence is ~ 1% for Runcorn. Although
ranges up to ~3 km could be achieved in clear air (yellow), the graph demonstrates the
dominance of fog in determining the system availability, where the margin (magenta) in
falls to zero on a 300m path, a 200 m visibility fog. Rain and turbulence appear to have
relatively similar effects, at 99.99% availabilities,% in terms of system degradation.
Data rates of 125 Mbps are achieved in clear air with the link margins shown.
FSO margins as a function of path length
50
rain (99.99%)
40
margin (dB)
30
fog at 200m
visibilty
20
10
FSO clear air
0
-10
scintillation
99.99%
-20
0
1000
2000
3000
4000
path length (m)
Figure 2.3:FSO system performance in rain, fog and turbulent conditions
2.2.3 Giga bit/s Wireless LAN
The frequency bands above 60 GHz could facilitate Gigabit/s wireless LAN
applications for either indoor communications invery large buildings such as an
exhibition hall or enclosed spaces such as sports stadiums or large car parks. As
diffraction above 60 GHz is minimal, the wireless link would need to operate as a line
of sight system, although reflections and scattering from buildings could also provide
another method of connection. Table 2.2 indicates the parameters used in the
performance calculations. Rather than use an access point with an omni directional
antenna, it seems more practical to utilise the high-gain small-size features of antennas
20
Radio Systems at 60GHz and Above
characteristics in this band. A 15 dB gain antenna, which would be capable of
illuminating a 900 sector from the access point, has been used for the link budget
calculations, A small CPE antenna (5 cm diameter) of ~ 32 dB gain at 100 GHz
(50 beam width) would need to be directed towards the access point in order to establish
a connection. Data rates of ~ 1 Gbps seem possible up to several hundred metres range
with oxygen absorption around 60 GHz having little impact at these short ranges. Rain
fading, which for 0.01% of the time would add up to ~ 3 dB attenuation on a 300 m
path, could just be accommodated over the entire frequency range. Reuse distances are
examined in the next section. A margin of between 4 and 14 dB (figure 2.4a) is
achieved over the frequency range in clear air.
link length
transmitter antenna gain
Transmitter power level 60/100 GHz
receiver antenna diameter
receiver bandwidth
Margin for error free QPSK (BER of 1 in 10^4) with additional coding
rain rate for 0.01%
0.3km
15.0dB
16/10dBm
0.05m
700.0MHz
11.0dB
0.0mm/h
Table 2.2: Parameters for Gigabit Ethernet
Margin for
Gbit wireless LAN
margin (dB)
20
15
clear air
99.99% rain
10
5
0
40
60
80
frequency (GHz)
Figure 2.4a: Giga bit/s WLAN performance
21
100
Radio Systems at 60GHz and Above
2.2.4 Broadband fixed wireless access
Broadband fixed wireless access (BFWA) might be considered as a logical extension of
the high capacity Wireless LAN application discussed above. The base station/access
point parameters remain fairly similar but the CPEs would require much larger antennas
to cope with the increased range up to 1.5 km.
The margin calculations (figure 2.4b, below) indicates that a more than adequate system
performance is achieved at 150 Mbps for better than 99.99% availability over most of
the band (except above 90 GHz, where maximum range would be limited to 1.3 km),
using the parameters in Table 2.3. A lower margin ( ~ 99.9%) could be maintained in
the absorption band for all but 6 GHz of the band, where the margin falls below zero.
This level of performance, at data rates of ~ 150 Mbps or more (if 16QAM or 64QAM
is deployed), would clearly be sufficient for commercial operations delivering very high
capacity broadband services. Multiple sector antennas at the base station with narrower
beams could raise the capacity of the base station significantly. For instance a sector
angle of 150 would be achieved with a base station antenna aperture of < 2cm at 100
GHz. Thus the increased gain (plus 8dB) could be used to raise data rates to ~ 700
Mbps/sector with QPSK. A base station with a capacity of ~ 17 Gbps would be
possible, with the deployment of 24 sectors.
Although the advantages of very small reuse distances in the 60 GHz band are still
available, the potential for exploiting them are diminished as the range increases. An
adequate margin might be achievable at 1 km range, even in the absorption band.
However, at a range over 1.5 km the extra rain attenuation and oxygen absorption could
add another ~ 10 dB, making adequate system performance with a commercial quality
of service (QoS) in the 55 to 65 GHz band very difficult to achieve over significantly
more than 1 km.
In conclusion it would appear that the above 60GHz bands have considerable potential
for short range (up to ~ 1.5 km) wireless distribution systems with several Gbps
capacity for both indoor and outdoor applications.
BFWA
link length
transmitter antenna gain
Transmitter power level 60/100 GHz
receiver antenna diameter
receiver bandwidth
Margin for error free QPSK (BER of 1 in 10^4) with additional coding
rain rate for 0.01%
fog visibility
Scintillation level equivalent to
Table 2.3: Broadband fixed wireless access parameters
22
1.5
20
16/10
0.15
100
11
22
200
0.01
km
dB
dBm
m
MHz
dB
mm/h
m
% time
Radio Systems at 60GHz and Above
Margin (dB)
Margins for P-MP on a 1.5 km
path
25
20
15
10
5
0
-5
-10
clear air
(dB)
99.9%
rain
99.99%
rain
40
60
80
100
frequency (GHz)
Figure 2.4b:BFWA system performance
2.2.4.1 Frequency re-use distances
One of the main advantages of operations in the 60 GHz absorption band is the high
immunity from interference from other systems using the same band, even when located
in close proximity. The peak gaseous attenuation of ~ 16 dB/km provides a wireless
“fog” which allows much shorter reuse distances than in other parts of the spectrum.
Figure 2.5 demonstrates this feature through calculation of carrier (C) to interference (I)
ratios for several reuse distances. The wanted signal is based on a cell size of 0.5 km
and the interfering signal calculated from another access point separated by distances
ranging between 0.5 km to 16 km from the wanted access point. The horizontal lines
indicate the required C/I for QPSK (15 dB), 16QAM (22dB) and 64QAM (30dB),
respectively. It is interesting to note that even with separations as low as 0.5 km,
operation is possible in a band of about 7 GHz around 60 GHz, if QPSK modulation is
used. Alternatively, the separation of nodes needs to be increased to 2 km, for 64QAM.
However the margins shown in figure 2.4a & b were derived for QPSK; if 16QAM is
used they would be reduced by ~ 7 dB but satisfactory operation could still be achieved
with 64QAM up to ~ 80 GHz on paths < 300m.
23
Radio Systems at 60GHz and Above
C/I for a cell radius of 0.5 km for various reuse distances
40.0
0.5 km
1 km
30.0
C/I (dB)
2 km
4 km
8 km
20.0
16 km
QPSK
16QAM
10.0
64QAM
0.0
40
60
80
100
frequency (GHz)
Figure 2.5 : C/I values for various access point separations
2.2.5 Satellite communications and high altitude platform systems
2.2.5.1 Fixed satellite
Table 2.4a below lists the parameters used in the evaluation of the satellite
communication system margins. A 2 m diameter satellite dish could be accommodated
in the Ariane 5 payload compartment. Power levels of 13 dBW have been achieved at
20 GHz for space qualified power amplifiers (TWT) more than 20 years ago for the
ESA Olympus project. The projected 7 dBW at 100 GHz might be a more ambitious
target for satellite amplifiers, especially if solid-state amplifiers are specified. Although
achievable, the 1 metre diameter earth station antenna at 100 GHz would be a fairly
costly item. The parameters used, although technically achievable, do however
represent a limit of system performance for practical satellite communications systems.
The system performance evaluation (figure 2.6a) demonstrates that satellite systems
above 60 GHz are not very practical even with availabilities near 99.9% of the time.
This QoS is not met above 51.5 GHz. Thus even direct broadcast applications, which
only require 99.7%, would not be very practical, as very large high-specification
customer receiving dishes would be needed. Throughput raw data rates equivalent to
one typical satellite broadcast transponder (DVB-S standard) of 33 to 36 Mbps could be
achieved in 40 MHz bandwidth.
24
Radio Systems at 60GHz and Above
link length
36000
km
transmitter antenna diameter
Transmitter power level 60/100 GHz
2
13/7
m
dBW
receiver antenna diameter
receiver bandwidth
1
40
m
MHz
Margin for error free QPSK (BER of 1 in
8
dB
10^4) with additional coding
rain rate for 0.01%
22
mm/h
13 to 7 over frequency
satellite transmitter power
dBW
range
Scintillation level equivalent to
elevation angle
0.01
30
% time
degrees
Table 2.4a: parameters used for satellite communication system evaluation
Satcom performance on a 30
degree path (London)
clear air
(dB)
30
margin (dB)
20
99% rain
10
0
99.9% rain
-10
-20
40
60
80
100
frequency (GHz)
Figure 2.6a : satellite communications system performance
25
99.99% rain
Radio Systems at 60GHz and Above
2.2.5.2
Aircraft to satellite communications
Table 2.4b lists the parameters used in the aircraft to satellite performance evaluation.
As with the fixed satellite scenario system a 2 m diameter dish on the satellite is used,
with transmitter power levels of 13 dBW at 40 GHz tapering down to 7 dBW at 100
GHz. However the aircraft mounted antenna would now be only 0.5 m diameter (i.e. the
size of a typical satellite broadcast receiving dish)
The performance evaluation (figure 2.6b), for aircraft at heights of 5 and 10 km,
demonstrates that this aeronautical satellite systems could achieve a reasonable margin
(10 to 15 dB) over the entire band, except between 54 and 64 GHz, where oxygen
absorption, even at these altitudes, still dominates. Passenger aircraft generally fly well
above the weather, rain seldom occurring above 4 km height, except in tropical storms,
which are generally avoided by high-flying aircraft. The rain attenuation effects can
thus be discounted for this application. A throughput raw data rate, equivalent to one
typical satellite broadcast transponder (DVB-S standard) of 33 to 36 Mbps (or
equivalent to a high capacity on-board WiFi hot spot), could be achieved in the 40 MHz
bandwidth.
Although the system evaluation seems to produce a reasonable margin, deployment of
such a system would introduce other problems. The spot beam produced from a 2m
satellite dish, in a geostationary orbit at 100 GHz, would have a diameter of ~ 100 km.
An aircraft flying at ~ 800 km/h would traverse the beam in ~ 7 minutes. Even the
short-haul high-density passenger aircraft services in Europe would require a complex
multi-beam satellite antenna of at least 200 spot beams to provide full coverage.
However a satellite system for long distance airlines, which uses these millimetre wave
bands, would need a few hundred spot beams to cover typical long distance flight paths.
The business case for such a complex satellite might be difficult to make, even for the
high density Pacific and Atlantic routes. However the attraction of a relatively small
aircraft mounted antenna is a very positive advantage.
Aircraft to Satellite
link length
36000.0
transmitter antenna diameter
2.0
Transmitter power level 60/100 GHz
13/7
receiver antenna diameter
0.5
receiver bandwidth
40.0
Margin for error free QPSK (BER of 1 in 10^4) with additional coding 8.0
satellite transmitter power
13.0
satellite transmitter power
5.0
Scintillation level equivalent to
0.01
elevation angle
30.0
Table 2.4b: Aircraft to satellite communications
26
km
m
dBW
m
MHz
dB
dBW at 40 Ghz
dBW at 100 GHz
% time
degrees
Radio Systems at 60GHz and Above
margin dB
Margin (dB) to satellite
from aircraft (zenith)
20
0
-20
-40
-60
-80
-100
Margin at 10 km
(dB)
Margin at 5 km
(dB)
40
60
80
frequency GHz
100
Figure 2.6b :Aircraft to satellite system performance
2.2.5.3 High altitude platform systems (HAPS)
The parameters used in the system performance evaluation for high altitude platform
systems (HAPS) are shown in table 2.4c. RF power levels and antenna sizes are less
challenging than in the SATCOM applications. However unlike the applications
discussed in sections 2.2.1 to 2.2.4, the higher RF power levels (cyan curve in figure
2.1a) are required to produce viable link margins. It has been assumed that a link length
of ~ 100 km is a maximum realistic range for a HAPS deployed at 20 km height, where
the minimum elevation angle at the optical horizon is ~ 11o. Ground terminals with 0.2
m diameters have been chosen but increasing the size to 0.5 m diameter seems perfectly
practical, if an increase in the margin of ~ 8 dB was required.
The calculated margins are shown in figure 2.6c, where a ~ 99.9% availability is just
about achieved over the band from 70 to 80 GHz.. This availability (~ 99.9%) would
probably be sufficient for a residential service for distribution of video and broadband
data in remote areas, where no alternative broadband technology (other than satellite)
was applicable. It does not seem that increasing the ground terminal size to 0.5 m would
significantly alter the quality of service, in terms of outage time, in most of the wave
band.
It might be concluded that if HAPS is viable in the existing 47 GHz allocated band,
then, provided that the RF technology is available, even higher frequency HAPS up to
27
Radio Systems at 60GHz and Above
80 GHz are potential viable, although outage times would be larger than those at the
lower 47 GHz band.
HAPS
link length
transmitter antenna diameter
Transmitter power level 60/100 GHz
receiver antenna diameter
100.0
1.5
26/20
0.2
receiver bandwidth
50.0
Margin for error free QPSK (BER of 1 in 10^4) with additional coding 11.0
rain rate for 0.01%
22
HAPS transmitter power
0.5
Scintillation level equivalent to
0.01
elevation angle
11.0
km
M on HAPS
dBm
m at CPE
MHz
dB
mm/h
dBW at 40 GHz
% time
degrees
Table 2.4c: High altitude platform systems (HAPS)
HAPS margins on 11 degree path
clear air
margin
40
margin (dB)
30
rain
99.99%
20
10
rain
margin for
99.9%
time
rain
margin for
99% time
0
-10
-20
40
60
80
frequency (GHz)
Figure 2. 6c:HAPS system performance
28
100
Radio Systems at 60GHz and Above
2.2.6 Mobile systems communications and short range repeaters for back haul
2.2.6.1 Mobile systems communications
Mobile application using the millimetre wavebands have been studied recently (5th
framework project (EU) MBS (mobile broadband systems) [8]). The general concept of
positioning base stations/access points, in American traffic lights fashion at cross roads
or on lamp posts seem interesting concepts to explore. The parameters used for this
application are shown in table 2.5, where a 20 dB gain base station antenna
communicates with a patch antenna of a few centimetres diameter on the front and/or
rear of the vehicle. More than adequate performance (~ 99.99% availability in rain)
could be achieved at ranges of up to 700m for data rates of 100 to 200 Mbps (figure
2.7a) over all the band. This distance (0.7 km) probably represents the limit of range
due to blockage by fixed obstacles and other vehicles.
Although such a system might be practical in the regular grid layout of the street plan of
North American cities, it would be much more difficult to deploy in the more random
street layouts of European cities, residential areas and rural locations. Communications
systems for railways might also be another potential application.
As such systems would also have difficultly connecting directly to hand held devices, it
commercial appeal might be somewhat limited. However, millimetre wave bands (~ 78
GHz) are already being seriously considered for anti-collision radar devices. Some spin
off from this millimetre wave radar technology might find itself applicable to
communications and control aspects associated with automatic traffic control and
information systems in the future.
mobile
link length
0.7
transmitter antenna gain
20.0
Transmitter power level 60/100 GHz
16/10
receiver antenna diameter
0.05
receiver bandwidth (MHz)
100.0
Margin for error free QPSK (BER of 1 in 10^4) with additional coding 11.0
rain rate for 0.01%
22
fog visibility
200.0
Scintillation level equivalent to
0.0
Table 2.5 : Mobile systems communications
29
km
dB
dBm
m
MHz
dB
mm/h
m
% time
Radio Systems at 60GHz and Above
margin for mobile application with maximum
range of 0.7 km
25
clear air
margin
margin (dB)
20
fog margin
at 200m
visibility
scintillation
margin
99.99%
rain margin
for 99.99%
time
rain margin
for 99.9%
time
15
10
5
0
-5
40
60
80
100
frequency (GHz)
Figure 2.7a: Mobile system performance
2.2.6.2 Short range repeaters
Lamp post mounted repeaters in these wave bands have considerable merits for hybrid
systems using dual frequency bands. Millimetre wave repeaters, placed at intervals of
0.5 to 1 km in city and suburban areas, would act as both the backbone and distribution
points for a lower frequency system. Lower frequency wireless LANs or mobile
systems would provide the final connection to the customer terminals. Mesh systems
using the very high capacity and frequency reuse capabilities of these millimetre wave
bands, particularly between 55 and 65 GHz, have the potential for achieving a 5 Gbps
plus back haul capacity to provision the lower-frequency short-distance broadband
connections. Figure 2.7b indicates the substantial margin achieved on such a repeater
link with 10 cm diameter repeater antennas over an 800 m range with a 5 GHz
bandwidth (capacity ~ 7.5 Gbps).
This application could be considered as a wireless alternative to cable modem
distributions through hybrid fibre coaxial (HFC) networks. The proposed hybrid
wireless system has a major advantage over HFC installations in that it does not
encounter the major cost of digging trenches at £50/m. If lamp post mounted repeaters
are used AC power is already available for the repeaters. Backhaul bandwidth in excess
of ~ 5 GHz combined with customer connections well in excess of 100 Mbps (e.g.
equivalent to the maximum rates of. IEEE 802.11n) could be achieved.
30
Radio Systems at 60GHz and Above
margins for various meteorological conditions
on a 0.8 km path
25
clear air
margin
20
margin (dB)
fog margin at
200m visibility
15
scintillations
margin
99.99%
10
rain margin for
99.99% time
5
rain margin for
99.9% time
0
40
60
80
100
frequency (GHz)
Figure 2.7b: Performance of repeater link with data rate of ~ 7.5 Gbps
2.2.7 Personal communications and home networks
2.2.7.1 Personal communications
:
One of the very short-range applications considered was that of personal
communication between “worn” electronic monitoring devices and a pocket computer.
Ranges are necessarily short < 2m but the path profile would be anything but line of
sight. Millimetre wave are nor particularly suitable for such applications for two
reasons:
•
•
Their ability to penetrate or bend around obstructions is poor
The low antenna directivities required for personal communications are
generally produced by very small apertures. This can result in very high power
densities, which approach safety levels.
Table 2.6a indicates the parameters chosen for the evaluation, where antenna gains of 0
dB were used. Even at a data rate of 10 Mbps, it is difficult to sustain with a high
margin (figure 2.8a) even when free space path loss is assumed. Power levels of the
31
Radio Systems at 60GHz and Above
transmitter needs to be reduced to ~ 10 mw or less to comply with safety regulations.
This short-range application does not take advantage of the high gains, which can be
achieved with relatively small antennas in this band. Path losses would be expected to
be much greater than free space. However due to the very short range (2m) rain
attenuation is not an issue but wetting of antennas in damp conditions might be more
problematic.
Body communications
link length
2
m
Transmitter power level 60/100 GHz
0/0
dBm
Nominal transmitter antenna diameter
0.01
m
Nominal receiver antenna diameter
0.01
m
near field
2D^2/wavelength m
receiver bandwidth
10.00
MHz
C/N Margin for error free channel QPSK (BER of 1 in 10^4) with additional coding 11.00
dB
antenna size
1
cm^2
power density at 40 GHz at maximum device power
0.01
W/cm^2
Table 2.6a :Body communication system parameters
Margin (dB) for body commmunications
25
margin (dB)
20
15
Margin (dB)
10
5
0
40
60
80
frequency (GHz)
Figure 2.8a: personal communications performance
32
100
Radio Systems at 60GHz and Above
2.2.7.2 In house (Home) communications
In house or home communications are another potential application of millimetre wave
systems. However the same problems that occurred with personal communications are
encountered when these wave bands are applied to home communications. Short ranges
with non line of sight paths, combined with low gain antennas and power flux density
restrictions, reduce the practical link margins. The minimal effect of oxygen absorption
can be detected in the slight kink in the curve around 60 GHz.
The performance evaluations (Table 2.6b and Figure 2.8b) on paths up to 20 m length,
assuming again only free space loss, produce margins of only a 15 to 20 dB. This is
hardly adequate for paths, which could be anything but line of sight with the added
attenuation of transmission through building walls. Communications at millimetre wave
might be possible within one room, as scattering from walls could produce an adequate
signal level. Thus provided RF devices could be produced a very low cost, these bands
might become applicable for much higher data rate “Bluetooth” type applications.
Home wireless network
link length
20
Transmitter power level
10
transmitter antenna gain
3.0
receiver antenna diameter (D) (gains of 10 to 20 dB)
1
receiver bandwidth (MHz)
25.0
Margin for error free FSK (BER of 1 in 10^4) with additional coding 11.0
m
dBm
dB
cm
MHz
dB
Table 2.6b : In house(Home) communications
Margin (dB) for home wireless network with
range of 20 m
20
margin (dB)
15
10
Margin (dB)
5
0
40
60
80
frequency (GHz)
Figure 2.8b: In house (Home) communications
33
100
Radio Systems at 60GHz and Above
2.3 CONCLUSIONS
2. Millimetre wave communications systems at frequencies above 60 GHz have the
potential for very high capacities, especially as more than 10 GHz of bandwidth
is available in the current frequency allocations.
3. Spectrum that is not subject to the oxygen absorption effect exhibits behaviour
which is broadly similar to spectrum below 60GHz where, in the absence of
precipitation fading, the limit of propagation is the horizon.
At frequencies around 60GHz, the oxygen absorption band, with its peak attenuation
of ~ 16dB/km, produces the radio equivalent of a fog, thus suppressing long
distance transmissions. As a consequence the distance at which a frequency channel
can be “re-used” is much shorter. The re-use distance can reduce to as little as ~ 1
km in certain scenarios. This provides an increase in spectral efficiency as
frequencies may be re-used with minimal co-ordination distances.
4. Specific applications have been identified that require broad contiguous blocks
of spectrum e.g. radio transmission of gigabit ethernet services.
5. Millimetre wave communications applications need to operate over short paths
(< 10km) and also need to take advantage of the high antenna gains and
directivities, which can be achieved with small antenna sizes (typically 10 <
diameter < 30cms).
6. Two applications have been identified for further study. These are:
a. Wireless local area networks providing ~1Gbps capacity through
millimetre wave access points.
b. Very high capacity backhaul for either MESH or branch and tree
networks, operated in conjunction with very local wireless distribution
services at lower frequencies.
7. The exploitation of these bands requires the development of low-cost RF
technology.
8. Millimetre wave systems are not particularly suited to situations where long
range is required e.g. satellite or HAPS systems or where non-line of sight paths
are experienced (e.g. personal communications and home networks).
9.
Millimetre wave systems, at ranges of more than 100m, provide a much better
quality of service, in adverse weather conditions (rain and fog), than free space
optical (infra red) systems.
Table 2.7 contains a summary of the results obtained from the study of applications for
systems in the frequency band 60 to 100 GHz. Typical system parameters have been
assumed such as 35 cm diameter antennas for the line of sight application and 15 dB
34
Radio Systems at 60GHz and Above
gain (900 sector horns) for the hub in BFWA systems. Rain attenuation values for
0.01% outage for London, UK have been used to evaluate system performance.
The RF parameters were assumed to be those which might be achieved in a 5 year time
scale. Maximum RF power levels were assumed to reduce with frequency, from ~ 26
dBm at 60 GHz tapering off to 20 dBm at 100 GHz. However for most applications
these power levels were reduced by 10 dB, as a combination of larger antennas with
lower power transmitters seems a more practical solution Noise figure increased with
frequency from 2.4dB at 60 GHz to 4 dB at 100GHz.
System Application
Frequency range
(GHz)
55 to 65
Comments
65 to 100
Link lengths up to 4 km possible
Free space optical systems
(FSO) (for comparison)
IR bands 1.5 to 0.9
μm
Both with data rate of 150 Mbps for 99.99%
availability
Typical system achieves only 99% availability on paths
of ~ 200m due to fog
Giga bit/s Wireless LAN
60 to 100
Line of sight point to point links
(LOS)
Broadband fixed wireless access
(BFWA)
Satellite communications
(Satcom)
Link lengths > 2 km impractical due to gaseous and
rain attenuation
Short range (~ 300 m) system operating at 1 Gbps with
small antennas (~ 5 cm aperture) will achieve working
margin even in rain (99.99% availability) assuming
line of sight connections
55 to 65
55 to 65
Very short frequency reuse distances (~1 km) possible
(see BFWA)
Operational margin up to 1 km; reuse distances ~ 1km
60 to 80
80 to 100
Operational margin up to 1.5 km; reuse distances ~
2km
Systems use QPSK, 150 Mbps and 99.99% availability;
very high capacity possible
Satcom not practical due to very high oxygen
absorption
53 to 67
67 to 100
Aero satellite communications
< 99.9% availability for capacity ~ 40 Mbps
technology stretch to limit to achieve even this poor
level of performance
Aero satellite not practical in this band due to very high
oxygen absorption
54 to 65
65 to 100
High altitude platform systems
(HAPS)
Operational margin for 40 Mbps service achieved as
rain attenuation above 5 km is zero. However very
small spot beams of 100 km diameter.
Nor practical for HAPS
52 to 70
70 to 100
Mobile systems
Availability near 99.9% for service at ranges up to 100
km
99.99% availability over almost all frequency range up
to 1 km for 100 Mbps service. Small patch antennas (5
cm diameter) on vehicle with American traffic light
55 to 100
35
Radio Systems at 60GHz and Above
style mounted access point
Short range repeaters for
network backhaul
55 to 100
Personal communications
55 to 100
Home communications
55 to 100
99.99% availability over 0.5 to 1 km paths with very
high capacity (5 Gbps); very short reuse distances,
similar to BFWA in 55 to 65 GHz band
RF power limited by safety; low gain antennas and non
line of sight scenario. Application not really suitable
for these frequency bands
Similar restrictions apply to personal communications.
RF power limited by safety; low gain antennas, non
line of sight conditions and very poor wall penetration.
Application not really suitable for these frequency
bands
Table 2.7: Summary of characteristics of various applications
2.4 REFERENCES
1. “Cellular Radio Access for Broadband Services” (CRABS AC 215) EU Fourth
Framework project http://www.telenor.no/fou/prosjekter/crabs/index.html
2. “Efficient Millimetre Broadband Radio Access for Convergence and Evolution”
(EMBRACE),
EU
Fifth
Framework
project
http://www.telenor.no/fou/prosjekter/embrace/index.htm
3. “ A study into the theoretical appraisal of the highest usable frequencies” Radio
Communications Agency Project (ref AY 4329)
4. “Attenuation by atmospheric gases”, Recommendations ITU-R p676-5, ITU
Geneva
5. “Propagation data and prediction methods required for the design of terrestrial
line of sight systems”, Recommendations ITU-R P530-10, ITU Geneva
6. “Propagation data and prediction methods required for the design of Earthspace Telecommunication systems”, Recommendations ITU-R P618, ITU
Geneva
7. Chandler, T. J. and Gregory, S “The Climate of The British Isles”, Longman,
London and New York, p390, 1976
8. “Mobile
Broadband
Systems”
EU
Fourth
Framework
project
http://www.cordis.lu/infowin/acts/ienm/bulletin/06-1997/mbs.htm
36
Radio Systems at 60GHz and Above
3
IDENTIFICATION OF KEY OBSTACLES TO BAND USE
3.1 INTRODUCTION
Unlike lower frequencies, semiconductor integrated circuits do not provide the complete
answer at millimetre waves. Significant amount of the product size and cost consists of
passive components based on waveguide structures, used for implementing and
enclosing filters, diplexers, gain stages and interconnects. This complex of plumbing
must be replaced by a technology that can scale down in cost as market size and
applications expand. The radio link must evolve in cost effectiveness in a manner
similar to the cellular phone, the PC and digital cameras. New architectures must be
developed with a low-cost appliance-design mindset.
During the last twenty years there has been a general trend towards higher frequencies.
A review of the current status of transmitter and receiver technology for higher
frequencies (above 60GHz) is presented in this section under the title “Classical
solutions”. This review is a giving general understanding of the potentials of the current
technology.
However the trend towards the higher frequencies is in large part a consequence of
technology development driven by scientific applications in astronomy and remote
sensing. Concentrating in the frequency range 60 to 100GHz and the commercial
applications presented in section 2 the receiver and transmitter technology is also
discussed from a more practical point of view based on the most recent solutions (after
2000) .
3.2 TRANSMITTER TECHNOLOGY
3.2.1 Classical solutions
For generating CW ( Continuous Wave ) power a variety of electron vacuum and diode
structures can be used , all of which fall into one of four categories:
•
•
•
•
Direct generation at the frequency of interest.
Up conversion from a lower frequency
Down conversion form a higher optical frequency.
Power Combining
Three aspects of performance are considered:
•
•
•
Available power
Bandwidth
Frequency and phase performance.
37
Radio Systems at 60GHz and Above
Direct generation at the frequency of interest
Solid-state: Solid-state sources are finding an increasing number of applications as
sources of microwave power in the frequency range 1-100GHz. These sources are
reasonably compact, affordable and practical for most millimetre-wave applications. In
addition amplifier products are provided to enhance the power generation capability of
the basic oscillators or other sources such as up-converters and frequency multipliers.
Several different devices are employed to produce these sources. The most commonly
used devices are: Gunn Diodes ( Gallium Arsenide-GaAs and Indium Phosphide-InP ) ,
IMPATT diodes (Silicon and Gallium Arsenide ) and GaAs FET,HEMT and other
three-terminal devices. The frequency of operation, power output, tenability and other
performance characteristics determine which device will provide optimal results and a
cost-effective solution. [1, 2, 3]. Figures 3.1 and 3.2 show the output power of Gunn and
IMPATT diodes as a function of frequency. In frequency range of our interest (60100GHz) the power decreases as the inverse of frequency.
Figure 3.1: Output power of Gunn diodes as a function of frequency.
38
Radio Systems at 60GHz and Above
Figure 3.2: Output power of IMPATT diodes as a function of frequency. Figures beside
each data point indicate the percentage DC to RF power conversion efficiency.
Gunn and IMPATT diodes are the most commonly used active devices for tunable
oscillators. Gunn diode oscillators using GaAs or InP diodes operate over the 18 to 170
GHz with power levels ranging from a few milliwatts at the high frequency end to about
400 mW at the lower frequencies. These oscillators are mechanically tunable over a
fairly wide range, offering up to 40% of their centre frequency. A limited amount of
electrical tuning is achieved either by varying the bias voltage or through the use of a
tuning varactor within the oscillator. Gunn oscillators generally produce very low noise
content and a free of spurious signals. They make excellent sources for local oscillator,
transmitters and signal generators. These oscillators can be phase-locked to a low phase
noise, high stability reference signal at RF of microwave frequencies.
Vacuum electron devices: There are many designs of vacuum electron tube, yielding
power from frequencies as low as a few GHz right up into the THz part of the spectrum.
The methods by which the radiation is generated vary, but all tubes contain a source of
electrons - usually a heated cathode - and a subsequent accelerating potential to create
an electron beam. A good review of the various operating principles of the various
devices has been made by Bhartia and Bahl, [4]. This text also discusses the range of
frequency obtained from each tube type (namely klystrons, backward wave oscillators
and gyrotrons) as summarised in the Figure 3.3.
39
Radio Systems at 60GHz and Above
Figure 3.3: High frequency capability of vacuum tube devices.
The klystron was one of the first tubes utilised for the generation of millimetre waves,
and the particular design used at high frequencies is known as the reflex klystron. The
conventionally manufactured reflex klystron, which is limited to frequencies of about
200 GHz [4], has an output power of about 10 mW and a mechanical tuning range of
only a few GHz
In a backward wave oscillator (BWO) an electron beam interacts with radiation
propagating in the opposite direction along the slow wave structure. Energy is coupled
from the electron beam to the wave, leading to amplification of the latter. A magnetic
field is applied parallel to the tube axis to confine the electron beam. Characteristic of
BWOs developed in the past by Thompson-CSF are presented in the following table.
The table also points to the limited tube lifetime, a problem which is believed to persist
to date.
Tube
Type
Centre
Frequency
(GHz)
Power
Output (W)
Bandwidth
(GHZ)
Voltage (kV)
Current
(mA)
Average Life
(hr)
CO80
40
10-40
1
3-6.9
60-80
5000
CO40
70 or 74
3-15
3
3-6
60
4000
CO20
136 or 154
1.5-3
2-4
3-6
60 (max)
2000
CO10
282
0.2-1
15
5-11
30 (max)
1000
Table 3.1: Typical Characteristics of BWOs. Tubes manufactured by Thompson-CSF
France
40
Radio Systems at 60GHz and Above
The backward wave oscillator is a very useful laboratory source of CW radiation.
However, it has fundamental drawbacks ( expensive, short operation time, high required
Voltage for operation) for commercial use for the application discussed in section 2.
Up conversion from a lower frequency
The generation of harmonic frequencies from a fundamental frequency source has been
the traditional method of providing LO power within the millimetre and sub-millimetre
wave region. In concept, generation of power through frequency multiplication is
simple. Low frequency power is introduced into a non-linear circuit element; power
generated by the non-linearity at a selected harmonic is subsequently output.
Invariably, a semiconductor diode is used to generate the desired harmonic, and circuit
filters reject unwanted frequencies.
The following figure shows a typical example of a frequency multiplication scheme in
which a fundamental oscillator (a Gunn oscillator or voltage controlled oscillator etc.) is
applied to a diode multiplier. The output of the multiplier can, by design of the
embedding circuit, provide different harmonic content and hence different degrees of
frequency up-conversion, i.e., multiplication.
Fundamental Oscillator
Waveguide Coupler
Frequency Multiplier
xN
Output
Power
Phase Lock
Harmonic Mixer
Figure 3.4: Schematic of a typical (sub) mm wave frequency up-converter system
The advantages of frequency up-conversion include:
•
•
•
•
Relative ease of implementation at frequencies of our interest (60-100GHz)
Use of low power, solid state technology;
Multiplier structures are relatively straightforward to interface to a heterodyne
mixer via, for example, a feedhorn antenna or by direct connection using
fundamental mode waveguide; and
Solid state power generation through frequency multiplication has an excellent
heritage of use in numerous ground based, airborne and space borne heterodyne
radiometers.
41
Radio Systems at 60GHz and Above
Planar varactor/varistor diode multipliers: Frequency multiplier designs that attempt
to terminate harmonic frequencies within the internal circuit through cunning balanced
arrangements have generally proved impractical with whisker contacted varactor and
varistor diodes. Planar diode technology has several advantages:
•
•
•
•
Circuits are easier to assemble, and rugged;
Planar diode technology allows the possibility of balanced diode designs that
terminate harmonics within the diode circuit, thus simplifying the RF circuit. In
principle this permits more efficient frequency multiplication at a higher
harmonic number;
It allow greater predictability in circuit fabrication, and consequently is more
amenable to computer aided circuit design; and
It allows the possibility of integrating small arrays of diodes, with consequent
improvements in power handling.
In concept, the monolithic circuit, in which active diode is fabricated on the native
circuit substrate, is straightforward [5 ]. Air bridges are generally used to reduce the
parasitic capacitance, together with proton isolation to reduce parasitic conduction.
Disadvantages of the monolithic circuit are that it is manufactured for a specific
application (and therefore may be costly), and becomes very small as the frequency
increases. RF circuit losses may be high. The Jet Propulsion Laboratory (JPL) and the
University of Virginia (UVA) have developed processes (e.g., the UVA MASTER
processes) for the integration of the active diode element with the RF circuitry on a
quartz substrate (described in the following section). JPL has taken device fabrication a
stage further with the MOMED diode [6]. Multiplier designs that incorporate this
concept [7] have been reported with good efficiency, using integrated varactors in a
balanced configuration. However, there remains the problem of poor heat sinking, and
consequently, for frequency multipliers, the input power is currently limited to around
40mW.
HBV Diode multipliers:Since 1980 most frequency multipliers have used varactor, or
varistor diode technology. The recent invention of the heterostructure barrier varactor
diode (HBV) at Chalmers University, offers a promising alternative to the Schottky
barrier varactor diode. In concept, the HBV uses material engineering to stack several
varactors on top of each other. Thin barriers of high band gap material are positioned
between the modulation regions in order to prevent unwanted parasitic current flow.
This approach has the advantage that for higher frequencies and powers the intrinsic
device area can be maintained without a subsequent increase in its capacitance.
A further attractive feature of the HBV is its symmetrical CV characteristic, which
occurs because there is no Schottky contact formation. When used to frequency
multiply, the HBV inherently produces only odd order harmonics. As in the case of
balanced pairs of Schottky varactor diodes, this simplifies the RF circuit design, since
fewer harmonic terminations need to be simultaneously optimised, and allows the
possibility of frequency multiplication factors of 3, 5 or even 7. The HBV has also
42
Radio Systems at 60GHz and Above
shown itself to be able to handle high input powers, and sub-millimetre HBV
multipliers have exhibited maximum efficiencies at input powers of 150mW compared
with ~40mW for the single Schottky barrier varactor diode [8].
Figure 3.5 : Planar HBV tripler, illustrating internal waveguide circuit and diode
Down Conversion from a higher optical frequency
Photomixing: Photomixers are optical heterodyne devices, converting the difference
frequency between two visible or near infrared laser beams into an oscillating
electromagnetic field in the GHz or THz range. Photodiode technology has advanced
significantly in the last few years due to the movement of the telecommunications
industry towards ever increasing data rates. The need for low loss and high bit rates
requires highly transparent, low dispersion fibres, which is provided by specialised
inorganic glasses operating predominantly at wavelengths around 1.55 µm
Power Combining
It is possible to raise the output power of solid state oscillators through the use of power
combining techniques. These permit the outputs of several devices to be coherently
added, thus increasing the available output power.
Two different power combining principles have been utilised: a) an open cavity FabryPerot resonator and b) a waveguide structure.
43
Radio Systems at 60GHz and Above
Figure 3.6: Schematic drawing of grooved mirror Fabry-Perot power combiner.
In the first approach [9], the individual Gunn diodes are coupled by reflection from the
curved mirror and power is optimised by translating the laminae in the grooved mirror.
Recent refinements in this quasi-optical technique have enabled powers of 90 mW to be
realised at 90 GHz from fundamental mode InP diodes. One advantage of this power
combiner design is that the frequency may be stabilised by applying feedback to one
diode only.
Figure 3.7:Schematic drawing of WR-6 waveguide cavity for power combining InP
Gunn diodes
A second approach has incorporated two appropriately spaced InP Gunn devices in a
rectangular waveguide cavity [10]. The power extracted at 100 GHz was 300 mW
44
Radio Systems at 60GHz and Above
Available Transmit Power
Figure 3.8 illustrates the power outputs available from various sources over a range of
frequencies. This figure deliberately includes frequencies much higher than our area of
interest (60-100GHz) for a better understanding of the potentials of the different
sources. We can see that the available power decreases as the frequency increases. What
is mentioned here applies also to the Local Oscillators.
Available Output Power
Milliwatts
100
Fundametal power
x2
10
Gunns, (amplifiers)
x3
BWO tubes
1
Upconverted power
x4, or x5
0.1
Diode multipliers
Downconverted power
cascaded multipliers
Photonic mixers
.01
500 GHz
1,000 GHz
1,500 GHz
Figure 3.8: Available output powers from different devices
The available power summary should be used with care.Only those devices are included
which show most promise. The following Tables summarize the various devices.
Technology Potential
Source
Gunn diodes
Frequency multipliers
Current availability
20dBm at 100 GHz, but availability
decreasing (difficult to obtain InP
diodes)
20dBm at 100 GHz, but limited
source (TRW, Inc.)
For power see chart
BWOs
Mature technology
Photonic mixers.
~1mW at 200 GHz
Power amplifiers
45
Potential availability
In principle, + 20dBm at 150 GHz in
10 years, if diode technology is
developed
Expect up to +20dBm at 200 GHz
within 10years
Further development in hand. A goal
of 1 mW at I THz is thought to be
realistic
10 mW at 200 GHz, (development of
better diode technology)
Radio Systems at 60GHz and Above
Bandwidth
Source
Gunn diodes
Bandwidth
Typically a few percent of the
centre frequency
Comments
Available power decrease with tuning
range
Frequency multipliers
Typically a few percent of the
centre frequency
Power amplifiers
Wideband
In principle possible to tune; but
difficult, as is the design of wideband
multiplied sources
Only limited by bandwidth of
amplifier
BWOs
Photonic mixers.
Depends on type of structure
Tuneable
Wide band sources, easy to tune by
changing laser frequency
Convenience
Source
Gunn diodes
Convenience
Excellent, typical solid state diode
component
Frequency multipliers
Excellent
Power amplifiers
Excellent
BWOs
Inconvenient
Photonic mixers.
Good
Comments
Limited only by bandwidth of
amplifier
Limited lifetime, HV power supply,
Russian technology
Requires laser power supplies
Frequency and Phase Characteristics
In general, free running oscillators are not very stable, whether a Gunn diode, electron
tube or optical laser. Frequency and phase stability are best achieved by locking the
oscillator to a lower frequency standard. In this case phase noise is generally related to
the lower frequency standard, degraded by the relevant multiplication standard.
-9
Stability (∆ f/F) <1 x 10 and a frequency placement of < 1kHz have been routinely
demonstrated at frequencies up to ~300 GHz.
3.2.2 Recent Transmitter technology for 60-100GHz
The transmitter provides a carrier signal modulated by the data to be transported across
the radio link.
Transmitters can be configured to operate using linear devices or within the saturated
region of the active devices.
In all cases a source of carrier signal is required. This may be a fundamental mode
oscillator or can be derived from a carrier source operating at a sub-multiple of the
output frequency followed by a multiplier. Fundamental operation conceptually requires
the smallest number of active devices. However at high mm-wave frequencies it can be
46
Radio Systems at 60GHz and Above
less cost effective particularly if feedback stabilization is required to provide frequency
stability. In addition it is necessary to provide isolation between the oscillator and any
sources of variable return loss to avoid the oscillator being de-tuned by the load
presented by an antenna, modulator or other circuit elements.
Figure 3.9: Direct frequency modulation of the source.
In an FM (frequency modulated), or CPM (continuous phase modulation) transmitter
the data stream can / is restricted in bandwidth using a pulse shaping filter. This allows
the bandwidth of the transmitted signal to be restricted. This filter is normally
implemented at the base-band frequency range of the modulating signal. Subsequent
amplifier / multiplier stages can be operated in a saturated region without causing the
spectrum to degrade such that the transmission bandwidth is increased. This allows the
transmitter to operate with maximum power for a defined size of active device (See
Figure 3.9).
Source
Modulator
Amplifier
Base-band
Modulation
Figure 3.10: Direct modulation following the source.
The source can be followed be a modulation stage (Figure 3.10) using an amplitude or
phase modulator. This device can be operating in a linear region or as a non-linear
device, for example a phase reversing switch or an opto-electric modulator. Whilst it is
conceptually possible to operate on the RF channel with a channel shaping filter this is
not generally practical for systems in the mm-wave region. Thus if any non-linear
elements are present in the modulator or subsequent stages the transmit spectrum will
exhibit a sin(x)/x response and will occupy significantly more spectrum than the
minimum necessary from a Nyquist consideration.
47
Radio Systems at 60GHz and Above
Source
Band-pass
Filter
Mixer
Amplifier
Modulated Spectrum
Figure 3.11: Linear up-conversion of a modulated carrier.
A linear up-converter can be realized using an up-converting mixer followed by a band
selection filter and linear amplifier (Figure 3.11). This type of approach can support any
form of modulation subject to the linearity of the mixer and amplifier maintaining an
appropriate EVM (error vector magnitude).
The three technical approaches, briefly described above, form the basis of today’s
commercial supply market at 57-64GHz.
A hybrid approach can be implemented using a source and modulator / up-converter
operating at a sub-multiple of the output frequency. This is then followed by a
multiplier stage to achieve operation at the final output frequency. This approach is only
suited to constant envelope forms of modulation unless spectrum expansion due to
sin(x)/x can be accepted.
This fourth approach is used by the Durham 60GHz channel sounder.
3.3 RECEIVER TECHNOLOGY
3.3.1 Classical Solutions
Heterodyne mixer receivers (see Figure 3.12) which use high speed Schottky diodes for
the non-linear mixing element have been demonstrated at all frequencies up to at least
2,500 GHz.
Single moded waveguide, and corrugated feedhorn technology can be manufactured by
traditional, or micro- machining techniques for use at all sub-millimetre frequencies.
Superconducting mixer elements (superconducting tunnel junctions, hot electron
bolometers) routinely provide low noise performance approaching the quantum limit.
48
Radio Systems at 60GHz and Above
incoming
signal
mixer pre-amplification
IF amplification
xN
LO
Mixer receiver (for higher frequencies)
mixer
incoming
signal
pre-amplification
IF amplification
RF amplification
xN
LO
Heterodyne system with RF pre-amplification (for lower frequencies less than 100Ghz)
Figure 3.12: Heterodyne mixer receivers
The mixer stage is usually acknowledged as being the noisiest stage in the receiver so
an RF amplifier is positioned ahead of it to mask that noise with a higher signal level.
The RF-amplifier provides amplification for the signal as soon as it arrives from the
antenna. The amplified signal is then passed to the "mixer/oscillator". The purpose of
the mixer/oscillator is to translate the frequency of the incoming signal to the
"intermediate frequency", i.e. to the "IF amplifier". However as the frequency increases
the received signal cannot be amplified always directly (due to limitations of the
receiver technology at higher frequencies) but has to be down-converted first.
Amplifier Technology
At frequencies up to ~60 GHz, RF signal amplifiers are available from several
commercial suppliers. At higher frequencies, however, receivers may be manufactured
for a specific application and therefore may be costly. For example, InP MMIC
amplifiers developed by JPL/TRW are being used on the ESA Planck Low frequency
Instrument (LFI) instrument at 90 GHz, and InP HEMTs (available from Hughes) are
being used in the NASA Microwave Anisotropy Probe (MAP) space instrument at
similar frequency (custom built by the National Radio Astronomy Observatory).
49
Radio Systems at 60GHz and Above
Figure 3.13: MAP amplifier
Diode Mixer Technology
There have been significant developments in diode mixer technology in recent years.
It has been demonstrated that planar technology can give excellent performance at all
millimetre and sub-millimetre wavelengths (even up to 2,500 GHz).
Corrugated waveguide feedhorns for coupling to free space and waveguide mount
structures have been demonstrated to frequencies in excess of 2,500 GHz.
Fixed tuned waveguide mixer mounts have demonstrated excellent broadband
performance.
Receiver Performance
Figure 3.14 summarizes the current performance of receivers. This figure deliberately
(as Figure 3.8) includes frequencies much higher than our area of interest (60-100GHz)
for a better understanding of the potentials of the different receivers.
50
Radio Systems at 60GHz and Above
Available Receiver Performance
Noise Figure
15
12
Receiver Nooise Figure
Amplifier technology
9
FP diode mixer
SHPdiode mixer
6
Superconducting mixer
3
500 GHz
1,000 GHz
1,500 GHz
Figure 3.14: Summary of available receiver performance
LO Requirements
The difficulty in generating power has been outlined in the section on ‘Transmitters’. In
turn, this creates a problem for heterodyne receiver systems, because of the heterodyne
requirement for Local Oscillator (LO) power.
Mixer type
Single ended diode mixer
Sub-harmonic diode mixer
LO power requirement
~1mW at fundamental frequency
~3 mW at half the fundamental
frequency
few μWs at fundamental frequency
Superconducting mixer
Receiver Potential
Source
Diode mixer
Current availability
Reasonable
availability
from
commercial sources at frequencies
up to 400 GHz
Available from specialist suppliers
at frequencies up to 1,000 GHz
SIS mixer
Only available
suppliers
from
specialist
HEB mixer
Only available
suppliers
from
specialist
51
Potential availability
All solid state receivers exist now at
< 500 GHz; expect all solid state
receivers up to 1 THz within 10 years
Expect sensitivity to improve by less
than a factor of 2 during next ten
years
Available now – but cooling
inconvenience likely to remain
No major increase expected in
sensitivity
Available now – but cooling
inconvenience likely to remain
Radio Systems at 60GHz and Above
Bandwidth
Source
Diode mixer
Bandwidth
Full waveguide band
Comments
Limited by the LO injection network,
and IF matching circuit
SIS mixer
Full waveguide band
HEB mixer
Limited to a few GHz
Limited by the LO injection network,
and IF matching circuit
Limited to low IF frequencies by the
device operation
Convenience
Source
Diode mixer
Convenience
Excellent
SIS mixer
Inconvenient - requires cooling
HEB mixer
Inconvenient - requires cooling
Comments
Typical solid state diode component,
similar in operation to those at
microwave frequencies
requires quite complicated cooling
system
requires quite complicated cooling
system
3.3.2 Recent Receiver technology for 60-100GHz
Figure 3.15 shows a Receiver Topology. ( A more detailed diagram that Fig.3.12)
Figure 3.15. Heterodyne receiver structure.
The receiver is generally realized as a heterodyne system.
In this approach the incoming spectrum to the receiver is down-converted using a mixer
and local signal source. The local signal source can be derived in a similar means to that
used at the transmitter.
Since the power levels are generally lower in the receiver than in the transmitter it is
also possible to use a mixer that is “pumped” by a local signal source operating at a submultiple of the effective frequency.
52
Radio Systems at 60GHz and Above
This can result in a less efficient mixer performance. However this can be mitigated by
the inclusion of a low noise amplifier between the antenna and the down-converting
structure.
If a low noise amplifier is included in the signal path to the mixer then a method of
attenuating the noise power in the image response frequency band for the converter.
This requires either an additional filter of the use of an image rejecting mixer structure.
This structure requires two identical mixers with two sets of local source power to the
mixers.
When the receiver is deployed within a terrestrial link the noise power present in the
receiver is due to both the self noise of the receiver and the noise due to the temperature
of anything present within the beam of the antenna. At mm-wave with moderate to high
antenna directivity this usually includes ground and building clutter at ~300 Kelvin.
This has the effect of raising the apparent noise floor of the receiver. With a receiver
noise figure of 3dB this can be degraded to 6dB. With a receiver noise figure of 6dB
this can be degraded to 7.8dB.
Low noise figure requires additional gain prior to the mixer stages within the receiver.
Since the mixer stages provide the large signal distortion limits of the receiver high
levels of pre-mixer gain reduces the maximum signal levels that can be tolerated by the
receiver.
A trade off between noise figure and is required. A system noise figure of 7 dB to 10 dB
is usually practical for commercial systems.
3.4 COST OF TECHNOLOGY
It is extremely difficult to predict the future cost of technology. The following table is
an estimate of the current cost of some of the more critical components.
There is no intrinsic reason why the technology is more expensive than more
established lower frequency microwave technology. In fact, because the ‘active
circuits’ and components are generally smaller, they could in principle be cheaper.
Current cost strongly reflects the small numbers and specialist nature of the technology;
increased demand will drive a dramatic drop in cost
The cost of diode mixers operating at frequencies less than ~500 GHz has substantially
decreased in real terms during the last 5 years, by at least a factor of 2. This is a
consequence of increased familiarity, increased demand and more suppliers.
53
Radio Systems at 60GHz and Above
<
5K
GBP
5 –
GBP
Transmit components
Gunn
√
Varactor multiplier √
√
Gunn +multiplier
√
BWO tube
FIR laser
Receive components
90 GHz amplifier
√
Diode mixer (up to
200 GHz)
20K
20-50K GBP
>50k
GBP
Depending
specification
Depending
specification
√
√
Price strongly depends on
number purchased
√
In general transmitter/receiver technology has been developed significantly the last
years due to the trend towards higher frequencies. A variety of solutions have been
proposed in terms of components and system hardware. At the highest frequencies these
solutions might be relative specialized , limited in performance and expensive.
However at the frequency range 60 – 100 GHz transmitter/receiver technology is
reasonably mature and mass-produced systems are commercially available ( see sections
3.2.2 and 3.3.2). For example transmitters with 10mW output power and receivers with
10dB Noise Figure are available today to fulfill the radio link requirements for the
applications presented in section 2. .
3.6 REFERENCES
2.
3.
4.
5.
6.
7.
8.
9.
10.
on
√
3.5 CONCLUSIONS
1.
on
Hambleton, K.G(1974),’Microwave avalanche devices’, Journal of Physics
E: Scientific Instruments, Vol.7
www.millitech.com
www.castlemicrowave.com
Bhartia, P. and Bahl, I. J.,(1984) "Millimeter Wave Engineering And
Applications", Wiley, New York
Meola, R. et al.,(2000), Electronics Lett. 36(9)
Siegel, P. H et al., IEEE Trans. Microwave Theory Tech. 47(5), (1999)
Bruston J. et al., “Frameless Multiplier Diodes”, Proc. 11th Int. Conf. Space
THz Technology, Virginia 2000.
Mélique, X. et al.,(2000), Electronics Lett., 35(11).
Bae Jongsuck, Unou, -T, Fujii, -T and Mizuno, -K (1988), “Spatial power
combining of Gunn diodes using an overmoded-waveguide resonator at
millimeter wavelengths”, IEEE Trans. Microwave Theory Tech. 46, pp
2289-94
Eisele S et al., (2000),IEEE Trans. Microwave Theory Tech. 48, 626
54
Radio Systems at 60GHz and Above
4
IMPLICATIONS OF LICENSED AND LICENCE-EXEMPT USE
& A SYRVEY OF INTERNATIONAL ACTIVITY IN BANDS 60100 GHz
4.1 INTRODUCTION
An international survey has been conducted into regulation, systems and applications of
frequency bands specified by the ITU-R for telecommunications use. The objective of
the survey was to determine how the higher frequency bands would be utilised in
various licensing scenarios (e.g. no, light touch and fully managed licensing). In
support of this, national regulators, voluntary standardisation bodies and commercial
organisations have been approached.
The main bands of interest internationally are 60-61, 64-66, and 71-76/81-86 GHz.
4.2 CURRENT UK POSITION
The current UK position may be summarised on the basis of the document 'United
Kingdom Frequency Allocation Table 2004, Issue No. 13', which is reproduced as
Annex 6 of this paragraph (FAT).
The National Frequency Planning Group (NFPG) is responsible for maintaining the UK
FAT. The NFPG updates the tables following proposals from Government Departments
and also clears ECC Decisions with implications for the UK’s radio spectrum within
government. The NFPG is part of the subordinate committee structure under the
Cabinet Official Committee on UK Spectrum Strategy. The National Frequency
Assignment Panel (NFAP) operates under the NFPG: it considers requests for frequency
assignments and maintains the National Frequency register (NFR). Ofcom provides the
secretariat to the committees, updating and maintaining the associated databases.
All frequency assignments registered on the NFR have to be considered by the NFAP.
However, this can be a lengthy process and the Panel has recently agreed that, in certain
frequency bands where there are no sharing concerns, spectrum may be assigned on the
NFR before being discussed at a Panel meeting.
‘Block cleared spectrum’ at January 2005 includes:
57.0 – 59.0 GHz
Primary Fixed
RR 5.547 identifies the band for high-density applications. There is
primary Mobile allocation but this is not used. There are also co-primary
allocations to the EESS (passive) and Space Research (passive)
services. In addition, there is a co-primary allocation to the inter-satellite
service at 57.0 – 58.2 GHz, the power of which is limited by RR 5,556A,
RR 5.556 permits use of sub-band at 58.2-59.0 GHz for Radio
Astronomy but this is not used in the UK.
55
Radio Systems at 60GHz and Above
64.0 – 65.0 GHz
Primary Fixed
RR 5.547 identifies the band for high-density applications in the HDFS.
There are also co-primary allocations for the Mobile (except aeronautical
mobile) and Inter-Satellite services but these are not used in the UK.
RR 5.556 permits use of the sub-band at 64.0 – 65.0 GHz for Radio
Astronomy but this is not used in the UK.
65.0 – 66.0 GHz
Primary Fixed
RR 5.547 identifies the band for high-density applications in the HDFS.
There are also co-primary allocations for the Mobile (except aeronautical
mobile) and Inter-Satellite services but these are not used in the UK.
There are also co-primary allocations to the EESS, SR and IS services
and decisions taken at WRC-97 to make the 64-66 GHz available for
HDFS through RR 5.547 took into account the sharing environment with
the EESS, SR and IS services.
The Earth Exploration Satellite Service, Space Research and InterSatellite services are not using the 64-66 GHz band in the UK.
The UK plays an active role in the ECC/ERO, complies with Decisions and observes
Recommendations.
ERC Report 25 - FMWG European Common Allocation Table - may be summarised as
follows:
Band (GHz)
Reported utilisations
Standards
59 - 61
Defence harmonised band
61 - 62
Fixed
ERC REC T/R 22-03
ISM and SRD
ERC REC 70-03
62-63
Broadband mobile
ERC REC T/R 22-03
63-64
Road traffic
ERC DEC (92) 02
64-66
Fixed
ERC REC (05) 02 (June 2005)
66-71
Future civil
71-76 (81-86)
Future civil (+ defence)
Annex 4 to Doc. SE19 (05) 50 (May 2005)
76-77,5
Amateur
EN 301 783
Astronomy
ERC REC (92) 02
Road traffic
77,5-78
Astronomy
78-81
Radiolocation
Astronomy
81-86 (71-76)
Future civil (+ defence)
86-92
Passive
92-105
Short range radar
Annex 4 to Doc. SE19 (05) 50 (May 2005)
Astronomy
56
Radio Systems at 60GHz and Above
Recommendations have been made by SE19 (ECC/ERO) in respect of the bands at 6466GHz and 71-76 / 81-86GHz. The 64-66GHz recommendation has now been
published as (05)02 : it is largely based on a work item submitted by the UK. The
recommendation gives the guidelines for administrations to consider when
implementing their national regulations for fixed services: SE19 did not discuss mobile
use. The 71-76/81-86GHz recommendation on FS channel arrangements has also been
finalised and was adopted at the last WGSE meeting (6-10 June 05) for public
consultation.
ECC Document ECC/REC/(05)02 is attached to this report as Annex 8.
Draft ECC Document is attached to this report as Annex 7.
In summary, (05)02 (64-66GHz) states
ƒ band 'opened for use by fixed service (FS) systems in some European countries'
ƒ high density high capacity point-to-point links
ƒ ETSI spec TS 102 329
ƒ very short distance links 'call for a light licensing regime'
ƒ provides example in Annex 2
ƒ recommends administrations choose either
ƒ to allow assignments without a specific channel arrangement
ƒ or use simplified frequency slots as shown in Annex 3
ƒ administrations should define 'suitable safeguards for interference avoidance
between adjacent blocks'
And (05)07 (71-76 / 81-86GHz) states
ƒ very high capacity (up to 10 Gbit/s)
ƒ possibility of multiple channel frequency re-use
ƒ 1-2 km hop lengths
ƒ multiple services and applications without interference concerns
ƒ no need for coordination
ƒ recommends that Administrations choose either
ƒ to use whole or parts of the bands with the channel arrangements in Annex 1 and
Annex 2 respectively
ƒ or allow systems with 10 GHz duplex separation using blocks from 71-76/81-86
GHz as in Annex 3
It is interesting to note that ECC Recommendation (05)02 states
- that the very short distance links in the 64-66 GHz band call for a light licensing
regime;
and
- that the atmospheric attenuation in this band may not be sufficient to ensure that a
high density of links can be achieved without suitable management to avoid interference;
whereas Annex 4 to the Draft ECC Recommendation (05)07 states
- that the high frequency reuse achievable with the high gain, low size and high
directional pencil-sized beam antennas reduces the requirement for frequency planning
techniques and offers the possibility of deregulated telecommunications environment within
CEPT countries for various low power, low cost and short range fixed wireless systems;
57
Radio Systems at 60GHz and Above
This seems to imply that 65GHz needs 'light' regulation and the higher band needs no
regulation, based on oxygen absorption and on antenna beam size. In fact the text
reflects a drafting compromise:
the UK initiated the 64-66GHz work item
within CEPT and promoted light licensing which it had already adopted
internally. Other CEPT administrations preferred the more traditional licensed
approach. Recommendation (05)02 provides guidelines which include an example
(based on a UK Ofcom contribution) on how light licensing could be implemented for
those administrations wishing to implement light licensing. The final decision lies with
the local national administration concerned. The proposed new recommendation on 7176/81-86GHz addresses only the channel plan for these bands and does not highlight
any particular licensing approach.
The 63-64GHz band is also allocated to (RTTT) Road Transport and Telematics
also known as Intelligent Transport Systems (ITS) in the ECC Rec 70-03 and
UK FAT. Work is ongoing in ETSI/ISO/ITU to define the technical characteristics of
the system and the application is being considered for licence exempt use. In addition,
the USA, Canada, Australia and Japan have regulations allowing the use of low power
licence exempt equipment in the bands up to 66GHz for WPAN applications.
The current work item for SE19 is as follows:
SE WP Ref#
Subject Output
Start/Target
dates
New ECC Rec on frequency S: May 2004
arrangements for FS in T: June 2005
frequencies above 70 GHz,
focusing on 71-76 GHz band
Remarks
SE19_12
FS
above
70 GHz
Draft ECC Rec
approved for
public
consultation.
Liaison sent to
WGFM
No further work items have been proposed to date.
Some of the above data was supplied by
Nasarat Ali
Fixed Wireless Services
Ofcom
Direct Line: 020 7981 3126
[email protected].org.uk
58
Radio Systems at 60GHz and Above
4.3 SURVEY
4.3.1 Process
Questionnaires were issued to regulators, manufacturers, integrators and operators, at
three differing levels of complexity.
The first, initial, questionnaire was sent to all European regulators, a sample of nonEuropean regulators, and to a sample of manufacturers and operators. It was designed
to establish the correct contacts in the country, and to start the information gathering
process, whilst having a limited number of questions as it has been shown in the past
that including too many questions reduces the number of responses received. The
Questionnaire is shown in Annex 1. The list of recipients is given in Annex 2.
It was resent during March 2005 to the following regulators:
Albania, Belarus, Belgium, Bosnia, Bulgaria, Croatia, Denmark, France,
Macedonia, Greece, Hungary, Italy, Latvia, Luxembourg, Malta, Monaco, Poland,
Romania, Russia, Slovakia, Slovenia, Spain, Turkey, Ukraine, Vatican.
The initial questionnaire was further distributed to regulators outside Europe during
early February 2005. Annex 3 shows the selected countries which were chosen to give
a global sampling.
Two follow up questionnaires were then designed, one for regulators and one for
industry - these were issued to recipients who indicated a willingness to engage in the
process. The final process was in the form of face-to-face and telephone interviews, for
which a guidance structure was created. These interviews were held with a
representative number of manufacturers and operators.
In addition to the summary and discussion in the Paragraph below, a more detailed
summary of the data gathered for the bands at 59,3-66 GHz, 71-76 GHz, 81-86 GHz,
and 92-100 GHz is presented in following Annexes. Please note that contact
information is only given where the respondent differs from the addressee shown in
Annex 2.
4.3.2 European National Regulators
Final allocations of frequencies and the definition of licensing regimes in Europe is
devolved to national administrations. There is no simple position, despite all national
administrations expressing full support for the ERC process.
Of the 21 replies, only 8 had opened some or all of the bands. Estonia, Lithuania and
Finland have opened all the bands, on a fully-licensed basis. Switzerland has opened all
the bands currently available in the USA, but on a conventional, fully-licensed basis.
Luxembourg has opened 59-66 GHz, again on a fully-licensed basis. The Czech
Republic and Slovenia have opened the bands 64-66, 74-76, and 84-86 GHz, on a
59
Radio Systems at 60GHz and Above
lightly-licensed basis. Norway has opened 64-66 GHz, on the same basis as the USAFCC (which Norway describes as ‘either exempt or light’).
Germany and Denmark have not opened any bands as yet, but have said that when they
do, at least some of the bands will be lightly-licensed. France is reserving its position,
pending the outcome of various ERC decisions.
Austria
[email protected]
Cyprus
[email protected]
Czech Republic
[email protected]
Denmark
[email protected]
Estonia
[email protected]
[email protected]
http://www.sa.ee
Finland
[email protected]
http://www.ficora.fi/englanti/radio/
Taulukko5.htm
France
[email protected]
[email protected]
www.art-telecom.fr
Germany
[email protected]
None of the above bands open yet.
No decision taken on the licensing approach should they be
opened.
No-one has applied, nor has authorisation been given, for 60100GHz operation.
Will review when applications are submitted.
64-66 GHz only lightly licensed,
74-76 GHz only lightly licensed,
84-86 GHz only lightly licensed,
92-100 GHz not licensed.
None of the bands open yet.
If the 65GHz band opens then a light licensing regime is highly
possible to be implemented.
All bands are open for fixed link use, and all are on a fully
licensed basis.
All the bands are open for Fixed Link use, but there is no
detailed channel plan.
All are fully licensed.
Finland follows actively the work of ECC PT SE19.
Situation is under review, with a policy expected following SE19
decision. The information will be available on the EFIS web site.
None of the bands are yet open. Germany will follow presently
emerging CEPT recommendations as far as possible. It is
preferred that 59,3-66 GHz should be fully licensed. No
decision on licensing rules has been taken for the other bands.
59.3-64 GHz: shared civil and military use
64-66 GHz: civil use only
71-75,5 GHz: shared civil and military use
75,5-76 GHz: civil use only
81-84 GHz: military use only
84-86 GHz: civil use only
92-95 GHz: shared civil and military use
95-100 GHz: military use only
There are no working groups / operator groups within the
country that are active in these bands.
Hungary
None of the bands are open.
60
Radio Systems at 60GHz and Above
[email protected]
Policy is set out in two decrees:
Government Dec. No. 346/2004 (XII.22.)Korm.
Minister Dec. No. 35/2004 (XII.28.)IHM
Iceland
None of the bands are open yet.
In fact there are no links above 26GHz in operation.
[email protected]
Ireland
[email protected]
Liechtenstein
[email protected]
None of the above bands are open.
Trial licences are being awarded.
‘Strategic’ bands are:
64-65 GHz fixed point-to-point links
71-76 GHz fixed point-to-point links; paired with 81-86 GHz
77-81 GHz UWB automotive SRR
81-86 GHz fixed point-to-point links; paired with 71-76 GHz
75,5-76 GHz is allocated to (and used by) amateurs until 2006
Lithuania
[email protected]
Luxembourg
[email protected]
http://www.ilr.etat.lu/freq/legal/ind
ex.htm
http://www.ilr.etat.lu/rtte/interfac/i
ndex.html
Netherlands
All spectrum open except 94.0-94.1 GHz.
All bands are lightly licensed.
64-66 GHz is already open for fixed links;
59,3-64 GHz will be opened for fixed links at end-2005.
71-76 GHz is not open except 71-74 GHz harmonised NATO.
81-86 GHz is not open except 81-84 GHz harmonised NATO.
92-100 GHz is not open.
All open bands are fully licensed.
With the exception of the military allocations, there are no
operating systems.
None of the bands are open.
[email protected]
www.at-ez.nl/nfr/
Norway
[email protected]
Poland
64-66 GHz open. Currently drafting a text for the band 64-66
GHz. The band will either be licence-exempt or lightly licensed
(in practice licence-exempt with possibility of registering base
stations for protection). For the other bands the NPT has
received no applications. A final decision on which part of the
band to allocate for Fixed Links has therefore not been taken.
New contacts are dealing with the enquiry: reply awaited.
[email protected]
[email protected]
[email protected]
Portugal
None of the above bands open.
[email protected]
Sweden
No bands or part bands have been opened.
[email protected]
61
Radio Systems at 60GHz and Above
Slovenia
[email protected]
www.apek.si
Switzerland
[email protected]
64-66 GHz is open, lightly licensed.
It is planned to open 74-76 GHz and 84-86 GHz, also on a
lightly licensed basis.
T/R 22-03 is followed.
The national entry on www.efis.dk/search/general is not up to
date.
Frequencies 59.3-62 GHz, 64-66 GHz,
71-76GHz, 81-86GHz, 92-94 GHz,
94.1-100 GHz are open.
All of these bands are Fully Licensed,
due to sharing with military.
4.3.3 Non-European National Regulators
In the USA, the Federal Communications Commission (FCC) have made rules for the
57-64GHz, 71-76 GHz, 81-86 GHz and 92-95 GHz bands. These rules use a
nonexclusive licensing approach which is intended to provide interference protection
from the date that licensees register on a link-by-link basis in a national database.
Traditional frequency coordination between users will not be required of licensees.
The FCC rule making was initiated by a petition from Loea Communications, Hawaii,
for the establishment of service rules for the licensed 71-76 GHz and 81-86 GHz bands.
The rule making was also supported by more than a dozen leading organisations such as
Cisco, Harris, Andew, Stratex Networks, Ceragon Networks, Wireless Communications
Association (WCA) and the Fixed Wireless Communications Coalition (FWCC).
The FCC also permits unlicensed, indoor use of the 92.0-94.0 GHz and 94.1-95.0 GHz
bands by non-federal government users. This unlicensed indoor use will be governed
by Part 15 of the FCC’s rules and will be based on existing regulations for the 57-64
GHz band. The FCC have not authorised unlicensed use of the 71-76 GHz and 81-86
GHz bands.
A complete history of the 71-76 and 81-86 GHz filings can be found on the FCC’s
Millimetre
Wave
70-80-90
GHz
Service
website
at
http://wireless.fcc.gov/services/millimeterwave.
Canada is fully harmonised with the USA, and has adopted all the same bands, with the
same technical specifications and licensing regime.
Japan has opened band 59-66 GHz is available for unlicensed use.
Australia has opened band 59.4-62.9 GHz on a licensed basis (Radiocommunications
Class Licence 2000).
Singapore and Zambia have not opened any bands as yet, but will respond to market
demand.
All other recipients of the questionnaire are considering their responses.
62
Radio Systems at 60GHz and Above
Taiwan
Ching-Chich Lin (Mr.)
Zambia
[email protected]
Acknowledgement only at this stage.
Enquiry has been referred to the relevant department; further
information is promised.
All the bands in question are at the moment free. No operator
has asked for spectrum in these bands.
Philippines
General frequency clearances and/or assignment is done by
Frequency Management Division: [email protected]
but licensing is done by various units:
1. Radio Regulations and Licensing Department for private
networks, aeronautical services and maritime services:
[email protected]
2. Common Carrier Authorization Department for common
carrier services: [email protected]
3. Broadcast Services Department: [email protected]
Israel
Basat is responsible for telecommunications services, including
Bezeq services, international services and cellular telephony.
[email protected]
Canada
http://www.ic.gc.ca/cmb/welcomeic.nsf/
ICPages/ContactUs
Japan
[email protected]
Policy is determined by Industry Canada.
This is also the government department responsible for the
technical
standards of telecommunication and radiocommunication
equipment.
Fully harmnised with USA (which see).
Band 59-66 GHz is available for unlicensed use, with the
following specification:
Maximum output power is 10 mW
Maximum antenna gain is 47 dBi
Frequency stability within +/-500 ppm
Maximum Bandwidth is 2.5 GHz
Regulations for Enforcement of the Radio Law, 6-4-2 Specified
Low Power Radio Station, (11) 59-66 GHz band.
Singapore
[email protected]
Australia
USA
Bands unoccupied.
IDA welcomes applications for trials.
Bands will be opened once there is demand.
59.4 GHz to 62.9 GHz
Radiocommunications Class Licence 2000.
Output Power
(i) 10 mW (+10 dBm) maximum total peak transmitter power
into the antenna
(ii) 150 W (+51.8 dBm) peak maximum EIRP
57-64GHz open on a lightly licensed basis.
71-76GHz, 81-86 GHz and 92-95 GHz now open using webbased Link Registration System. Process takes 10minutes and
costs USD100 for 10years. Registration gives interference
protection.
63
Radio Systems at 60GHz and Above
4.3.4 IEEE
IEEE 802.15 has been set up to create standards for Wireless Personal Area Networks
(WPANs). Within 802.15, task group 802.15.3c is charged with creating a standard for
the physical layer at 57 to 64GHz in response to the USA-FCC’s allocation of a licenceexempt allocation in that band. The group is thought to be about two years from a
standard.
The graphic below is taken from ‘Understanding UWB - Principles & Implications for
Low-Power Communications,’ submission to IEEE802.15 Working Group for Wireless
Personal Area Networks, Doc. IEEE802.15-03/157r1, March 2003. It was based on
work by R. Aiello, J. Ellis, U. Kareev, K. Siwiak, and L. Taylor.
Throughput Capacity
[Mbps]
WPAN region
1000
100
UWB
802.11a
802.11b
802.15.4
fixed wireless
broadband region
UWB
region
10
Potential 60 GHz region
WLAN
region
1
UWB reach out with
less data, but with
location (SG4a)
0.10
0
10 20 30
40
50
60
70 80 90 100
1k
Range [m]
The targets for 802.15.3c include:
• Bit Rate and Range - More than [email protected]
• uncomplicated coexistence with other 802 systems (TG3a, Bluetooth, etc)
• operate with the 802.15.3 MAC without fundamental changes.
• simple spectrum mask
• robust indoor multipath
• frequency stability within +/-500ppm
• simple signal processing
• Power Output by comparison with TG3a Alt-PHY Technical Requirements
• 100mW or less @100Mbps
• 250mW or less @200Mbps
• Power save function
4.3.5 Industry
The high data rates associated with the frequencies above 60GHz are primarily targeted
for use by carriers as a fibre alternative. The applications include short hops, base
64
Radio Systems at 60GHz and Above
station backhaul, fibre bridging, ultra-high capacity access, storage area networks and
data centres. The target deliverable bandwidths for these applications are between 1 and
10Gb/s over distances up to 2km. The primary driver for installing such a radio network
would be the very high cost or difficulty of installing a fibre network.
Currently this high Gb/s capacity requirement cannot be gained by utilising the lower
frequencies due to the regulatory controls and spectrum availability.
One of the key drivers in the take up of Gb/s radios will be the procurement pricing.
Products at this frequency see high manufacturing cost increases as the modulation
scheme increases. High order modulations such as 64/128QAM are expensive to
produce and significantly reduce the transmission path length. Adaptive modulation
schemes which will help manage the transmission path length are possible but
extremely expensive. Lower order modulation schemes such as QPSK and BPSK are
more spectrum hungry but permit lower product manufacturing costs.
Channel sizing is an issue at these bands. There is widespread support for the adoption
of 250MHz channels and allowing up to 5 to be grouped. The consensus view of
commercial respondents is that in the bands 57-64GHz and 71-76/81-86GHz, a lightly
licensed approach should be adopted, with effective permission being given for up to
the full nineteen 250MHz channels to be used by a single radio. Spectral efficiency will
be driven by the increased licence costs proportional to the number of 250 MHz
channels used. These channels are as noted in the ECC Document ECC/REC/(05)07.
Operators are now starting to deploy high frequency networks. Some examples are
given below:
ƒ
September 30, 2005 - GigaBeam Corporation announces that it has signed an
agreement with Eaton and Associates for the sale of 1 Gigabit WiFiber™ wireless
fibre links for the City of San Francisco Public Utilities Commission (PUC) as part
of their first phase of planned deployments to enable live video, data and voice over
IP (VoIP) communications. The Radios operate in the 71-76 GHz and 81-86 GHz
radio spectrum bands.
ƒ
01/04/05 - TESSCO awarded GSA Schedule to supply BridgeWave 60GHz
products to city, county, state and Federal government entities.
ƒ
September 21, 2005 - American IP has installed Gigabeam 71-76 GHz radios for
CompuCredit Corporation as an alternative communications link to back up existing
terrestrial fibre.
ƒ
Terabeam Corporation, 2003 announced today that OnFiber is use Terabeam’s
Gigalink™ gigabit Ethernet (GigE) wireless fibre system to extend its fibre optic
network to serve additional customers. The GigE Gigalink provides OnFiber the
ability to provide alternative connectivity options to its existing customer base as
well as expand its network reach. Currently, OnFiber operates fibre optic networks
in 14 major metropolitan areas throughout the U.S. Terabeam’s GigE Gigalink is the
first radio frequency (RF) product certified by the FCC that provides full duplex
65
Radio Systems at 60GHz and Above
Gigabit line rates. The GigE Gigalink provides an interface to a customer’s
communications network that transmits and receives signals at 1.25 gigabits per
second (Gbps), Global Infrastructure and Telecommunications Institute, Waseda
University Japan, 60GHz campus Links.
66
Radio Systems at 60GHz and Above
4.4 DISCUSSION
Expected applications for systems using the bands between 60 and 100GHz include
high-speed wireless local area networks, broadband wireless access systems for the
internet, point-to-point links and point-to-multipoint configurations.
The technology will in effect be equivalent to fibre-optic cables, filling gaps in current
fibre-optic networks in rural areas and inner cities where the cost of digging to lay
cables inhibits growth. Nevertheless, range is weather-limited to the order of a few
kilometres. The most typical application will perhaps be a campus setting where
buildings have not yet been connected to fibre.
Frequencies in the range 59,3-66 GHz have been allocated in Europe, USA and Japan,
with Latam, Africa and most of Asia-Pacific likely to follow suit. The allocations at 7176/81-86 GHz in the USA are in the process of being copied in Europe, though with
important differences of specification and licensing. The 92-95 GHz band is currently
only open in the USA. The consensus industry view is that the current USA regulations
favour market acceptance and promote competition; there are some concerns about the
European position.
A typical industry response is that provided by Dr Johnathon Wells of Gigabeam.
Gigabeam join with past-Chairman Powell of the USA-FCC in believing that the USA
rule-making encourages early and spectrally efficient deployment in the bands above
57GHz.
This is because:
ƒ The spectrum is regulated under FCC Part 101 rules, the same rules governing all
existing FS equipment in the USA.
ƒ The two 5 GHz channels (at 71-76/81-86GHz) are regulated to enable cost effective
gigabit and multi-gigabit FS equipment operating at distances of 1-2 kms with
99.999% weather availability.
ƒ A ‘light touch’ licensing scheme was created, whereby internet based coordination
and approval can be usually achieved in less than 30 minutes for around €100 per
license.
Together the 71-76 and 81-86 GHz allocation has enabled a wide range of new wireless
products and services to be introduced in the USA. Gigabit Ethernet radios operating at
1,25 Gbps are freely available, offering transmission over distances of over a kilometre
with availability statistics that cannot be matched by any alternative wireless
technologies. By 2006, the first 10 Gbps FS radios will become available, seriously
threatening fibre as the high capacity transmission medium of choice.
ECC/Rec/(05)07 identifies the need for above 70 GHz fixed links to provide 1-10 Gbit/s
broadband services over distances of 1-2 km for applications where fibre optic cables
are not cost-effective. The document acknowledges that this multi-gigabit capacity
cannot be served by lower frequencies due to their relatively narrow channel
bandwidths.
67
Radio Systems at 60GHz and Above
Industry believes that the key driver for this target market is product price. To compete
effectively with fibre, which is prevalent throughout Europe and the rest of the
developed world, products need to be low cost and easy to install and maintain. Low
modulation complexity products (e.g. FSK or QPSK) will dominate over more complex
radio products. The simpler architectures of lower complexity modulation radios will
result in lower cost and higher reliability products. Such products will also benefit from
improved performance due to transmitters operating with higher powers (less power
amplifier back-off) and with improved receiver sensitivities (lower receiver C/N)
allowing larger fade margins to be achieved and longer link distances to be realized.
One possible competitor to millimetre-wave FS and WPAN is Ultra-Wideband (UWB).
MW-FS/WPAN offer Gigabit speeds. However, they are affected by the well-known
propagation characteristics, and are both line-of-sight and weather-dependent. In this
respect thay have certain similarities to infra-red communication (standard IRDA),
which has not competed successfully with Bluetooth. It is possible that UWB will
become the non-line-of-sight technology for Gigabit personal area networking, and
MW-FS/WPAN would play the role of ‘fast IRDA’.
Nevertheless, MW-FS/WPAN has several advantages compared to UWB:
•
•
•
•
•
•
No interference to other systems because of large frequency difference
Good coexistence because of path-loss
Antenna directivity (UWB may be not allowed to use high gain antennas)
Simple modulation/demodulation (Spread spectrum schemes are essential for
UWB)
Simple signal processing (For UWB, complex technologies such as rakereceiver, or high frequency A/D, D/A converter and DSP will be needed for
signal processing)
Higher speed transmission (more than 1Gbps)
A further consensus is in support of the ‘Spectrum Commons’ concept for high
frequencies. This could be managed on a ‘light licensed’ basis in the manner adopted by
the USA-FCC. The thesis is well made by Dr. Daniel Kelley in ‘Economically Efficient
Licensing of the Millimetre Wave Band’. This argues that link licensing is
advantageous over spectrum auctions for a competitive and efficient market at these
frequencies.
68
Radio Systems at 60GHz and Above
4.5 CONCLUSIONS AND RECOMMENDATIONS
4.5.1 Market readiness and applications
The high data rates associated with the frequencies above 60GHz are primarily targeted
for use with carriers for fibre alternatives. Declared applications for these include:
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
Short alternative fibre hops - Last Mile Access and Infrastructure
Metropolitan Area Networks - Redundancy, Network Expansion or Private
Networks
Campus Area Networks - Hospitals, Schools, Military Bases, or Enterprises
Base station backhaul - WiMax, WiFi, Cell Antenna Extension, etc
Fibre bridging
Temporary Bandwidth - Disaster Recovery, Network Expansion
Storage links
Manufacturers are now launching useable product, especially near the oxygen peak at
60GHz. These products exploit USA-FCC rules and provide a range of typically 1km.
There is also some activity at higher frequencies with longer range but manufacturers
are waiting for orders before committing to production tooling. European and other
regulators are starting to respond, although the response is far from uniform, e.g.
between Europe, USA, and ROW. Within Europe some regulators are establishing
national regimes, but most have waited for the report of SE-19 (just available as this
interim report was in preparation). There is still a preponderance of formal licensing,
but some regulators will adopt a mix of unlicensed and lightly licensed processes.
4.5.2 Technical regulatory parameters
The following interim recommendations represent the consensus view of commercial
respondents. The conclusions and recommendations of the team on the current project
are presented in Paragraph 2 of this report.
Manufacturing industry (most active respondents are USA-based) and potential
importers/integrators and users recommend that the ECC should facilitate and
encourage simple architecture products wherever possible. They state that this will
allow cost effective products to be developed to satisfy the identified market
requirements; equipment of this kind is already available from the USA.
TPC
To provide an element of international standardisation and to encourage market growth
and product availability, TPC should not be mandatory in the bands 64-66GHz, 7176GHz and 82-86GHz.
69
Radio Systems at 60GHz and Above
Channel sizes
Due to the nature of the applications and the directivity of operational equipment in
these bands, there should be no restriction on channel size. 10GB/s radio links would
require the full 5GHz spectrum.
This is currently the case with the USA-FCC part 1010 which at 71-76 / 81-86GHz
allows operators to use the full 5GHz and has no defined channels. Similarly, the ETSI
TS 102 329 (64-66GHz for HDFS) permits links to operate in and across the entire
2GHz band.
The removal of channelisation in the USA is currently viewed as being a successful
move by a number of the USA stakeholders.
The USA-FCC has stated :
'We are convinced that elimination of the segmentation scheme will provide
manufacturers the freedom to produce radios utilizing a variety of modulation schemes
… thus lowering the cost of equipment for new entrants and spurring technological
development and rollout. Furthermore, we find that allowing users the maximum
flexibility in link design and the freedom to upgrade as their needs evolve will facilitate
new entry in this nascent service.'
(Allocations and Service Rules for the 71-76 GHz, 81-86 GHz, and 92-95 GHz Bands,
FCC Memorandum Opinion and Order 05-45, March 2005)
Maximum Power output (EIRP)
In order to obtain the QoS required for the delivery of the identified applications, the
consensus view is that the power levels given in annex 4 of the Draft ECC Document
ECC/REC/(05)07 ‘Radio Frequency Channel Arrangements for Fixed Service
System’ should be increased.
As shown below in the description of the trial of commercial equipment, the EIRP
limits of ECC/REC/(05)07 are not adequate for the delivery of services up to 2km
distance at 99.999% availability in the bands 71-76GHz and 81-86GHz.
The consensus view is that the limits in table A4.3 (shown in Annex 8 of this paragraph)
are increased to 19dBm for power at the antenna port for 1Gb FSK links in both the 7176GHz and 81-86GHz bands, and the limits in table A4.2 for 1Gb 16QAM links be
increased to 14dBm in both the 71-76GHz and 81-86GHz bands.
Modulation requirements
There should be no modulation requirements or restrictions. It is believed that
BPSK/QPSK will be used in the majority of links due to the link length requirements
70
Radio Systems at 60GHz and Above
4.5.3 Operating frequencies
As before, the following interim recommendations represent the consensus view of
commercial respondents. The conclusions and recommendations of the team on the
current project are presented in Paragraph 4.2 of this report.
To satisfy QoS requirements for the identified applications and to provide the required
channel bandwidths, the following bands should be opened:
Bands 59-66 GHz (57-59GHz has already been ‘block cleared’)
Bands 71-76 GHz
Bands 81-86 GHz
Bands 92-100 GHz
4.5.4 Licensing
Deployment of systems at high data rates of 1Gbps and above will not take place if
there is significant risk of interference. Nevertheless, these bands are ideally suited to a
‘spectrum commons’ approach: this is most likely to encourage innovative deployments
and to maximise spectrum efficiency. Therefore, all the above bands should be opened
on a ‘Lightly Licensed’ basis, perhaps adopting the USA-FCC licensing technique.
4.5.5 Further Work
The supply and operation of radio systems in the bands between 60 and 100 GHz is an
emerging market, with some very active participants, but it is far from mature. Several
vendors are making significant investments and operators are now installing viable
networks. However, the regulatory position is very confused, with wide differences in
allocated bands, channelisation, permitted power levels and licensing regimes between
different administrations. Even within Europe, there is wide divergence: some
regulators are following the lead of the USA-FCC, others are waiting for a consensus to
emerge from the ERC, whilst others do not see a need at these frequencies.
This unclear situation must impact on the willingness of European manufacturers to
invest in full scale production tooling, and is also likely to delay the development of
networks by multinational operators (although local small scale operators are already
importing USA-sourced equipment where allowed).
The European high frequency radio market has long suffered from a circularity of
process:
limited demand - delayed regulatory response - limited investment - limited demand
It is recommended that Ofcom maintain an ongoing interest in the development of a
Europe-wide regulatory regime in the frequency bands between 60 and 100GHz that is
sympathetic to the needs of both operators and manufacturers. And that the
71
Radio Systems at 60GHz and Above
development of both regulations and market is continuously monitored throughout
2006.
72
Radio Systems at 60GHz and Above
Annex 1: Initial questionnaire
Questions
59.3 – 66 GHz
71 – 76 GHz
81 – 86 GHz
92 – 100 GHz
1 Does your national entry on the yes/no
ERO
website
(www.efis.dk/search/general)
give current data?
yes/no
yes/no
yes/no
2 Please indicate if the following yes/no
bands (or parts of bands) are
open for use for Fixed Links
yes/no
yes/no
yes/no
3 If the bands are open, are they
a) Licence-exempt
b) Lightly licensed
c) Fully licensed
a) Licence-exempt
b) Lightly licensed
c) Fully licensed
a) Licence-exempt
b) Lightly licensed
c) Fully licensed
www. ….........
www. ….........
www. ….........
a) Licence-exempt
b) Lightly licensed
c) Fully licensed
4 Is there a web address where www. …..............
more information is available?
5
Please note any specific
guidance or national interface
documents / specifications that
are relevant for operation in
these bands.
6 Are there any working groups /
operator groups within your
country that are active in these
bands? If so please advise any
contact details if possible.
73
Radio Systems at 60GHz and Above
Annex 2 :Target Recipients of Initial Questionnaire
Country
Name
Email address
Tel number
Albania
Frederic Kote
[email protected]
+355 42 32 131
Austria
Walter Marxt
[email protected]
+431 797 31 4200
Belarus
Vladimir Striharchuk
[email protected]
+375 1722 75536
Belgium
Gino Ducheyne
[email protected]
`+32 2226 8818
Bosnia &
Herzegovina
Mrs Gordana Trapara
[email protected]
+387 33 250 600
Bulgaria
Nikola DIKOV
[email protected]
+359 2 949 2663
Croatia
Ante DODIG
[email protected]
+385 1 489 60 00
Cyprus
Dr Stelios D HIMONAS
[email protected]
+357 22 814854
Czech Republic Zdenek VOPARIL
[email protected]
+420 2 24004 758
Denmark
Jørgen Lang Nielsen
[email protected]
+45 35 45 02 60
Estonia
Arvo RAMMUS
[email protected]
+372 693 1154
Finland
Mrs Margit HUHTALA
[email protected]
+358 9 6966 425
France
Jean-Yves Montfort
[email protected]
`+33 1 4518 7376
Fyr Macedonia Kosta TRPKOVSKI
[email protected]
+389 2 224 511
Germany
Angelika MÜLLER
[email protected] +49 228 615 3240
Greece
Mr N Benmayor
[email protected]
`+301 650 8571
Hungary
Dr Ferenc Horvath
[email protected]
`+36 1 461 3430
Iceland
Gudmundur OLAFSSON
[email protected]
+354 510 1500
Ireland
Jim CONNOLLY
[email protected]
+353 1 804 9635
Italy
Francesco TROISI
[email protected]
`+39 06 5444 4952
Latvia
Guntars ROZENTALS
[email protected]
+371 7 333 034
Liechtenstein
Farshad HOSSEINI
[email protected]
+423 236 64 84
Lithuania
Tomas BARAKAUSKAS
[email protected]
+370 5 210 56 23
74
Radio Systems at 60GHz and Above
Luxembourg
Edouard WANGEN
[email protected]
+352 45 88 451
Malta
Adrian GALEA
[email protected]
+356 25 99 36 18
Monaco
Raoul VIORA
[email protected]
+377 93 15 85 51
Netherlands
Fokko G. BOS
[email protected]
+31 70 379 81 15
Norway
Geir Jan Sundal
[email protected]
`+47 22 82 48 81
Poland
Jerzy Czajkowski
[email protected]
+48 22 53 49 159
Portugal
Mrs Luisa Mendes
[email protected]
`+351 21 721 2200
Romania
Mrs Ioana SLAVESCU
[email protected]
+40 21 410 60 03
Russia
Ms Anna Skokova
[email protected]
`+7 095 771 8493
Slovakia
Milan MIZERA
[email protected]
+421 257 881 600
Slovenia
Nikolaj SIMIC
[email protected]
+386 1 583 63 00
Spain
Ricardo Alvarino Alvarez
[email protected]
`+34 91 346 1507
Sweden
Catarina Wretman
[email protected]
`+468 678 5576
Switzerland
Philippe Horisberger
[email protected] `+41 32 327 5572
min.ch
Turkey
Ahmet Hicabi ERDINC
[email protected]
+90 312 550 5020
UK
Anthony WALKER
[email protected]
+44 20 7783 4124
Ukraine
Oleksandr POPOV
[email protected]
+380 44 226 26 73
Vatican City
Constantino PACIFIC
[email protected]
+ 39 06 6988 43 08
75
Radio Systems at 60GHz and Above
Annex 3: Further distribution of initial questionnaire
The following countries were contacted commencing February 2005.
•
•
•
•
•
•
•
•
•
•
•
•
Australia - Australian Communications Authority (ACA)
http://www.aca.gov.au
Canada - Canadian Radio Television and Telecommunications Commission
http://www.crtc.gc.ca/eng/welcome.htm
Israel - Ministry of Communications
http://www.moc.gov.il/
Jordan - Telecommunication Regulatory Commission
http://www.trc.gov.jo/
Mexico - Comisi
ederal de Telecomunicaciones
http://www.cft.gob.mx/
Nepal - Nepal Telecommunications Authority
http://www.nta.gov.np/
Philippines - National Telecommunications Commission (NTC)
http://ntc.gov.ph/
Singapore - Infocomm Development Authority of Singapore
http://www.ida.gov.sg/
Sri Lanka - Telecommunications Regulatory Commission
http://www.trc.gov.lk/
Taiwan - The Directorate General of Telecommunications
http://www.dgt.gov.tw/
USA - Federal Communications Commission (FCC)
http://www.fcc.gov/
Zambia - Communications Authority
http://caz.gov.zm/
76
Radio Systems at 60GHz and Above
Annex 4: Second Stage Questionnaires
Two questionnaires were used; one for manufacturers and integrators, and one for
operators. The questionnaires were sent only to selected respondents to the initial
questionnaire
77
Radio Systems at 60GHz and Above
Survey to Manufacturers and Integrators (Confidential)
Dear xxxxxxxxxxxxxxx
Sinon Ltd is part of a consortium engaged by Ofcom, the UK radiocomms regulator, which has
been charged with investigating existing and future use of the frequency bands between 60GHz
and 100GHz allocated to the Fixed Service by the ITU.
We would be grateful if you could help us by answering the questions below and emailing back.
An MS Word copy of the questions is also attached.
If this has been sent to the wrong department within your organisation, please could you advise
us whom to contact.
Thank you for your help.
Xxxxxxxxxxxxx
Xxxxxxxxxxx
xxxxxxxxx
78
Radio Systems at 60GHz and Above
Item
59.3 – 66 GHz
71 – 76 GHz
81 – 86 GHz
92 – 100 GHz
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
<Comment>
Market Growth
Can you identify any
specific countries that have <Comment>
licensed these bands?
Are there any countries
within the above where the <Comment>
regulatory regime is not
helpful to the market?
In what way could the situation
be improved?
Do you favour a licensed or
unlicensed approach?
Please identify any barriers that
are affecting market growth for
your product.
Your
regulatory
recommendations
Please quantify any boundary
conditions and limitations that
should be incorporated in any
new licensing of the above
bands, from the following list:
Max power output (EIRP)
Should TPC be required?
Should there be channel size
restrictions?
If so what? (MHz)
What modulations should be
allowed?
Should there be any spectral
efficiency requirement?
If so, what? (bits/Hz)
Current Deployments
Are
there
any
reference
deployments that you can
identify? (Countries)
Are you aware of any power
level regulations in these
countries?
TPC requirements?
Channel size restrictions?
Allowed modulations?
Spectral efficiency limits?
79
Radio Systems at 60GHz and Above
80
Radio Systems at 60GHz and Above
Survey to Operators/Potential Operators (Confidential)
Dear xxxxxxxxxxxxxxx
Sinon Ltd is part of a consortium engaged by Ofcom, the UK radiocomms regulator, which has
been charged with investigating existing and future use of the frequency bands between 60GHz
and 100GHz allocated to the Fixed Service by the ITU.
We would be grateful if you could help us by answering the questions below and emailing back.
An MS Word copy of the questions is also attached.
If this has been sent to the wrong department within your organisation, please could you advise
us whom to contact.
Thank you for your help.
Xxxx
Xxxxxxxxxxxx
xxxxx
Item
Please say if you have an
interest in using any of these
frequency bands for high
capacity short haul links in the
future.
Which year and quarter would
you wish to start deployment?
In each of these bands do you
have a preference for a licensed
or
unlicensed
regulatory
approach?
Are there any non-regulatory
issues which are hindering the
growth of FWA in these bands?
59.3 – 66 GHz
71 – 76 GHz
81 – 86 GHz
92 – 100 GHz
<Y/N>
<Y/N>
<Y/N>
<Y/N>
<date>
<date>
<date>
<date>
<licensed/
unlicensed>
<licensed/
unlicensed>
<licensed/
unlicensed>
<licensed/
unlicensed>
<comment>
<comment>
<comment>
<comment>
81
Radio Systems at 60GHz and Above
Annex 5: Regulators for possible Further Work
Argentina
Secretaria de Comunicaciones
Argentinean telecoms regulator, site is only
available in Spanish
Bahrain
Telecommunications Regulatory Authority Bahrain - The Telecommunications Regulatory
(TRA)
Authority is an independent body, and awards
http://www.tra.org.bh
licences to operate, and use radio spectrum.
Bolivia
Superintendencia de Telecomunicaciones Bolivia's telecoms regulator, the site is only
(SITTEL)
available in Spanish
Botswana
Botswana Telecommunications Authority Telecommunication authority for Botswana,
http://www.bta.org.bw
Southern Africa. Authority for fixed telephony,
mobile telephony, broadcasting, Internet, radio, and
satellite communications.
Brazil
ANATEL
Brazils' telecoms regulator press releases, English
version.
Brunei
Jabatan Telekom
Telecoms regulator for Brunei Darussalam. Is
currently part of the state owned land line network,
but is due to be separated prior to privatisation.
Burkia Faso
Direction g rale de l'Office National des State regulator - also operates the telecoms
t communications (ONATEL)
networks - site in French only
Chad
Government regulator, very little information on the
Minist• de Postes et T communications
site. Site in French only
Chile
Subsecretaria de Telecommunicacaiones Chile's telecoms regulator
(SUBTEL)
Columbia
Comisi
e
Regulaci
e Columbia telecoms regulator, only available in
Telecomunicaciones
Spanish
Dominica
ECTEL
Eastern
Caribbean
Telecommunications Authority
ECTEL
ECTEL
Eastern
Caribbean Telecommunications regulator for the Eastern
Telecommunications
Authority - Caribbean states of Commonwealth of Dominica,
http://www.ectel.info
Grenada, Saint Christopher and Nevis, Saint Lucia,
Saint Vincent and the Grenadines.
El Salvador
Superintendencia General de Electricidad y El Salvador's telecoms regulator. Site available in
Telecommunicaciones
Spanish only.
Egypt
Telecommunications Regulatory Authority Local regulator - site in both Arabic and English
(TRA)
Georgia
Georgia - Ministry of Posts and Georgia's telecoms regulator, part of the
Telecommunications government.
http://www.iberiapac.ge/mincom/
Grenada
ECTEL
Eastern
Caribbean Eastern Caribbean Telecommunications Authority
Telecommunications Authority
is the telecommunications regulator for five Eastern
Caribbean states.
Hong Kong
Office of the Telecommunications Telecoms regulator for Hong Kong - available in
Authority (OFTA)
English and Chinese
http://www.ofta.gov.hk/frameset/home_ind
ex_eng.html
India
Telecom Regulatory Authority of India Government department, responsible for landline
(TRAI)
and wireless telecoms. Site in English only
Iran
Islamic Republic of Iran Broadcasting
Government department that oversees telecoms
http://www.irib.com/
regulation. Site is available in Farsi with some
English news
Jabatan Telekom Jabatan Telekom Brunei
Telecoms regulator for Brunei Darussalam.
82
Radio Systems at 60GHz and Above
Brunei
- http://www.telecom.gov.bn/
Features information on services and regulations as
well as forms and contact information.
Japan
Ministry of Public Management, Home Japan's telecoms regulator. Available in Japanese
Affairs, Posts and Telecommunications
and English.
http://www.soumu.go.jp/
Kenya
Communications Commission of Kenya
Established in 1998 - site in English only.
Korea
Ministry
of
Communications
and South Korean government department. Responsible
Informations
for all digital communications and media. Site in
Korean, Chinese and English
Lebanon
Ministry Of Telecommunications
Lebanese government department responsible for
telecoms regulation. Site is available in Arabic and
English
Lesotho
Lesotho - Telecommunications Authority Governmental
regulatory
agency:
provides
http://www.lta.org.ls
information on its activities.
Macau
Office
for
the
Development
of Telecoms regulator for Macau - available in
Telecommunications and Information Chinese, Portuguese and English.
Technology
Malaysia
Communications
and
Multimedia Government linked department responsible for
Commission (MCMC)
telecommunications - site mainly in English
Mali
National operator - site availability is erratic
Soci• des T communications du Mali
Mauritania
Office des Postes et T communications
National regulator - site in French only
Mauritius
The Ministry of Information Technology Government department that is responsible for
and Telecommunications
telecoms regulation.
Mongolia
Post and Telecommunications Authority of Implementation Agency of Mongolian government,
Mongolia
Post and Telecommunication Authority is the policy
http://www.pta.gov.mn
making, project planning and executing agency for
the nationwide information and communication
infrastructure development.
Morocco
National Agency for the Regulation of Recently created independent telecoms regulator in
Telecommunications (ANRT)
Morocco. Site is mainly in French and Arabic, but
some English also.
New Zealand
Commerce Commission of New Zealand Government department that also manages telecoms
Nigeria
Nigerian Communications Commission
Government regulator - site in English only with
some pages still under construction
Pakistan
Pakistan Telecommunications Authority
PTA
was
formed
under
the
Pakistan
Telecommunication Reorganization Act, 1996 - site
only available in English
Papua New Guinea PANGTEL
Papua New Guinea telecoms regulator - looks after
telecoms, radio, tv, and amateur radio hams
Paraguay
Conatel, telecoms regulator
Paraguayan telecoms regulator - only available in
Spanish
Saint Christopher ECTEL
Eastern
Caribbean Eastern Caribbean Telecommunications Authority
and Nevis
Telecommunications Authority
is the telecommunications regulator for five Eastern
Caribbean states.
Saint Lucia
ECTEL
Eastern
Caribbean Eastern Caribbean Telecommunications Authority
Telecommunications Authority
is the telecommunications regulator for five Eastern
Caribbean states.
Saint Vincent and ECTEL
Eastern
Caribbean Eastern Caribbean Telecommunications Authority
the Grenadines
Telecommunications Authority
is the telecommunications regulator for five Eastern
Caribbean states.
San Marino
Segereteria di Stato per l'Industria, San Marino's telecoms regulator. Site in Italian only
l'Artigianato, la Cooperazione economica,
le Poste e le Telecomunicazione
Singapore
Infocomm Development Authority of Telecoms regulator for Singapore.
Singapore
South Africa
ICASA
The Independent Communications Authority of
South Africa was established in July 2000. It took
83
Radio Systems at 60GHz and Above
over the functions
Telecommunications
(SATRA)
84
of the South African
Regulatory
Authority
Radio Systems at 60GHz and Above
Annex 6: United Kingdom Frequency Allocation Table 2004
Issue No. 13
Key:
ITU FREQUENCY BAND
ITU PRIMARYALLOCATION (1)
ITU PRIMARYALLOCATION (2)
ITU Secondary Allocation (1)
ITU Secondary Allocation (2)
UK specific allocations, where made
59·3-64·0 GHz
64·0-65·0 GHz
INTER-SATELLITE
FIXED
RADIOLOCATION
INTER-SATELLITE
FIXED
MOBILE except aeronautical mobile
MOBILE
59·3-64·0 GHz – Ofcom (for the Fixed service) and
MoD (for the Mobile and Radiolocation services)
63-64 GHz shared with RTTT devices
65·0-66·0 GHz
66·0-71·0 GHz
EARTH EXPLORATION-SATELLITE
INTER-SATELLITE
85
Radio Systems at 60GHz and Above
SPACE RESEARCH
MOBILE 5.553
INTER-SATELLITE
MOBILE-SATELLITE
FIXED
RADIONAVIGATION
MOBILE except aeronautical mobile
RADIONAVIGATION-SATELLITE
71·0-74·0 GHz
74·0-75·5 GHz
FIXED
BROADCASTING
FIXED-SATELLITE (Earth to space)
BROADCASTING-SATELLITE
MOBILE
FIXED
MOBILE-SATELLITE (Earth to space)
FIXED-SATELLITE (space to Earth)
MOBILE
Ofcom (for the Fixed and Mobile services)
Space Research (space to Earth)
MoD (for the Fixed-Satellite and Mobile-Satellite services
75·5-76·0 GHz
76·0-77·5 GHz
BROADCASTING
RADIOASTRONOMY
BROADCASTING-SATELLITE
RADIOLOCATION
FIXED
Amateur
FIXED-SATELLITE (space to Earth)
Amateur-satellite
MOBILE
Space Research (space to Earth)
Space Research (space to Earth)
76-77 GHz shared with RTTT devices
Amateur and Amateur-Satellite use until 31December 2006
Ofcom for civil Radiolocation including RTTT
86
Radio Systems at 60GHz and Above
77·5-78·0 GHz
78-79 GHz
AMATEUR
RADIOLOCATION
AMATEUR-SATELLITE
Amateur
RADIOLOCATION UK5
Amateur satellite
Radio Astronomy
Radio Astronomy
Space Research (space to Earth)
Space Research (space to Earth)
76-78 GHz Ofcom for civil Radiolocation including RTTT
78-79 GHz Ofcom & MoD for civil/military Radio location
79-81 GHz
81·0-84·0 GHz
RADIO ASTRONOMY
FIXED
RADIOLOCATION
FIXED-SATELLITE (Earth-to-space)
Amateur
MOBILE
Amateur satellite
MOBILE-SATELLITE (Earth-to-space)
Space Research (space to Earth)
RADIOASTRONOMY
Space Research (space to Earth)
Ofcom (for the Fixed and Mobile services)
MoD (for the Fixed-Satellite and Mobile-Satellite services)
84·0-86·0 GHz
86·0-92·0 GHz
FIXED
EARTH EXPLORATION- SATELLITE (passive)
FIXED-SATELLITE (Earth-to-space)
RADIOASTRONOMY
MOBILE
SPACE RESEARCH (passive)
RADIOASTRONOMY
87
Radio Systems at 60GHz and Above
Continuum measurements are conducted between 86·0-92·0
GHz.
92·0-94·0 GHz
94·0-94·1 GHz
FIXED
EARTH EXPLORATION-SATELLITE (active)
MOBILE
RADIOLOCATION UK5
RADIOASTRONOMY
SPACE-RESEARCH (active)
RADIOLOCATION
Radioastronomy
Diazenylium line observations conducted between 92·0-95·0
GHz
Diazenylium line observations conducted between 92·0-95·0
GHz
MoD (for the Radiolocation service)
MoD (for the Radiolocation service)
94·1-95·0 GHz
95·0-100·0 GHz
FIXED
MOBILE
MOBILE
MOBILE-SATELLITE
RADIO ASTRONOMY
RADIONAVIGATION
RADIOLOCATION
RADIONAVIGATION- SATELLITE
RADIOASTRONOMY
Diazenylium line observations conducted between 92·0-95·0
GHz
Radiolocation
Used for multiple line and continuum observations between
MoD (for the Radiolocation service)
97·88-98·08 GHz
88
Radio Systems at 60GHz and Above
89
Radio Systems at 60GHz and Above
ANNEX 7: Draft ECC Document ECC/REC/(05)07
RADIO FREQUENCY CHANNEL ARRANGEMENTS FOR FIXED SERVICE SYSTEMS
OPERATING IN THE BANDS 71-76 GHz AND 81 - 86 GHz
Recommendation approved by the Working Group "Spectrum Engineering" (WGSE)
INTRODUCTION
The millimetre wave spectrum above 70 GHz is of increasing interest to service providers and systems
designers because of the wide bandwidth available for carrying communications at this frequency range.
These wide bandwidths are valuable in supporting applications such as extremely-high-speed data
transmission. Because of the unique nature of the propagation in the millimetre bands and possibility to
employ highly directional (pencil-sized) beams, multiple services and applications can be implemented
without interference concerns, thus ensuring highly efficient re-use of the frequency band.
The use of the 71 - 76 GHz and/or 81 - 86 GHz bands provides an inviting opportunity to cope with the
future market demands for increasingly high bandwidth access, in particular for Internet-bases
applications. Fixed radio links may be deployed much quicker and in certain cases are more cost efficient
than the wired networks, and as such the millimetre waves provide sufficient bandwidth for terrestrial
fixed links to compete or complement the fibre optic based access networks. The competing FSO (Free
space optics) systems are also emerging as a possible solution that on short distances can support
broadband capabilities (1-10 Gbit/s) with reasonable availability and reliability.
In the proposed scenario of using the 71 - 76 GHz and/or 81 - 86 GHz band for fixed services, it appears
possible to implement very high capacity (up to 10 Gbit/s) links with some 1-2 km hop lengths (line-ofsight conditions); these systems would allow a rapid and effective deployment of broadband capacity in
areas where fibre optic cables are not available or are not cost-effective.
The main features of operating fixed radio systems in this region of spectrum may be summed up as
follows:
• Availability of wide bandwidths, allowing for the low cost of traffic in terms of
bit/sec/Hertz/Euro;
• Possibility of multiple channel frequency re-use, thanks to the unique propagation conditions,
highly directional pencil-sized beams; this will also enable implementation of multiple services
and applications without interference concerns, obviating the need for coordination;
• Radio links are much easier to install comparing to alternative wire-bound solutions like fibre
optical links;
• Ability to ensure high security because of low possibility of interference/capture of signals.
Use of the spectrum above 70 GHz is the only viable solution for fixed links to achieve the above
objectives. The lower FS band at around 52 GHz (28/56 MHz channels) has similar propagation
conditions but does not provide sufficient space for truly wide band links.
Therefore the bands 71 - 76 GHz and 81 - 86 GHz may be considered suitable for high speed data FS
links.
It should be noted that the bands 71 - 76 GHz and 81 - 86 GHz are used in some countries by other
services or applications than FS civil links. In particular the bands 71 - 74 GHz and 81 - 84 GHz have
been identified as NATO Type 3 bands, i.e. for possible military use in NATO Europe. This should be
taken into account by administrations wishing to use whole or parts of the frequency bands 71 - 76 GHz
and/or 81 - 86 GHz for civil FS links.
90
Radio Systems at 60GHz and Above
“The European Conference of Postal and Telecommunications Administrations,
considering
a)
that ITU Radio Regulations (RR) and the European Table of Frequency Allocations and Utilisations
(CEPT/ERC Report 25) allocate the bands 71 - 76 GHz and 81 - 86 GHz on a primary basis to Fixed
Service as well as other co-primary services;
b) that the European Table of Frequency Allocations and Utilisations in ERC Report 25 identifies the
bands 71 - 74 GHz and 81 - 84 GHz as harmonised military bands for defence systems, but
recognises that these bands can be shared between civil and military users according to national
requirements and legislation (see ECA footnote EU27);
c)
that ITU RR No. 5.340 prohibits all emissions, inter alia, in the band 86 - 92 GHz, and care should
be taken to limit FS out-of-band emissions into that band;
d) that ITU RR No.5.149 applies to the frequency range 81- 86 GHz which urges administrations to take
all practicable steps to protect the radio astronomy service from harmful interference;
e)
that the propagation characteristics of the 71 - 76 GHz and 81 - 86 GHz are ideally suited for use of
short range FS links in high density networks;
f)
that, as the propagation loss difference in the bands 71 - 76 GHz vs. 81 - 86 GHz is within the range
of 1 dB for the hop lengths of up to 2 km, this also suggests the possibility of using these two bands
together for FDD links with large duplex separation, if necessary;
g) that the FS uses envisaged in this band include various transmission digital systems with different
modulation schemes, system gains and providing high data rate capacities;
h) that a large number of new FS systems could be deployed in the range of 71 - 76 GHz and 81 - 86
GHz, relieving congestion in the lower frequency bands;
i)
that the 79 GHz frequency band (77 - 81 GHz) has been designated to the SRR equipment in
accordance with ECC/DEC(04)03;
recommends
1)
that administrations wishing to use whole or parts of the frequency bands 71 - 76 GHz and/or 81 86 GHz for civil FS links should consider the channel arrangements given in Annex 1 and Annex
2 respectively;
91
Radio Systems at 60GHz and Above
2)
that administrations wishing to assign duplex channels, may use the bands 71 - 76 GHz and 81 86 GHz as paired bands, or as a separate single bands containing internal duplex separation, as
illustrated in Annex 3;
3)
that when extremely high bit rate system with high system gain is required, administrations may
allow flexible aggregation of any number of 250 MHz channels, as illustrated in Annex 3;
4)
that until the relevant ETSI technical specifications for FS in these frequency bands are developed,
administrations may find examples of technical parameters for civil FS links in these bands in
Annex 4.
Note:
Please check the Office web site (http//:www.ero.dk) for the up to date position on the implementation
of this and other ECC Decisions.
92
ECC/REC/(05)02
Page 93
Annex 1
RADIO-FREQUENCY CHANNEL ARRANGEMENTS IN THE BAND 71 - 76 GHz
Let
fr
fn
n
be the reference frequency of 71000 MHz,
be the centre frequency of a radio-frequency channel in the band 71 - 76 GHz,
be the channel number,
then the centre frequencies of individual channels with 250 MHz separation are expressed by the
following relationship:
fn = fr + 250·n
MHz
where:
n = 1, 2, 3, ..., 19
Note, that the specified channels may be used to form either TDD or FDD systems within the single band,
or in combination with other band specified in this recommendation.
Calculated parameters according to ITU-R Rec. 746
XS
MHz
250
n
1,...19
f1
MHz
71250
fn
MHz
75750
Z1S
MHz
250
Z2S
MHz
250
TABLE A1.1
XS
Z1S
Z2S
Separation between centre frequencies of adjacent channels
Separation between the lower band edge and the centre frequency of the first channel
Separation between centre frequencies of the final channel and the upper band edge
ECC/REC/(05)02
Page 94
Annex 2
RADIO-FREQUENCY CHANNEL ARRANGEMENTS IN THE BAND 81 - 86 GHz
Let
be the reference frequency of 81000 MHz,
be the centre frequency of a radio-frequency channel in the band 81 - 86 GHz,
be the channel number,
fr
fn
n
then the centre frequencies of individual channels with 250 MHz separation are expressed by the
following relationship:
fn = fr + 250·n
MHz
where:
n = 1, 2, 3, ..., 19
Note, that the specified channels may be used to form either TDD or FDD systems within the single band,
or in combination with other band specified in this recommendation.
a.
Calculated parameters according to ITU-R Rec. 746
b.
2.
3.
250
X
S
M
H
z
4.
1,...19
n
5.
6.
f1
M
H
z
81250
7.
8.
85750
f
n
M
H
z
9.
Z
1
S
10. M
H
z
250
11. Z
2
S
12. M
H
z
250
TABLE A2.1
XS
Z1S
Z2S
Separation between centre frequencies of adjacent channels
Separation between the lower band edge and the centre frequency of the first channel
Separation between centre frequencies of the final channel and the upper band edge
ECC/REC/(05)02
Page 95
Annex 3
EXAMPLES OF PAIRING AND AGGREGATING CHANNELS
IN FREQUENCY BANDS 71 -76 / 81 - 86 GHz
The principle of using the channels from within the bands 71 - 76 GHz and 81 - 86 GHz in a single
duplex FDD arrangement is described in the Fig. A3.1.
f1
f2
f3
f4
71 GHz
f5
…
19x250 MHz channels
f19
f1' f2' f3' f4' f5'
76
81
…
19x250 MHz channels
Fig. A3.1. Combining the channels from 71 - 76 / 81 - 86 GHz bands into a single
FDD arrangement with duplex separation of 10 GHz
The principle of duplex channels within a single band 71 - 76 GHz or 81 - 86 GHz with duplex separation
of less than 5 GHz is shown in Fig. A3.2.
f1
f2
71/81 GHz
f3
f4
f5
…
250 MHz channels
f1' f2' f3' f4' f5'
250 MHz channels
…
76/86
Fig. A3.2. Combining the channels from single 71 - 76 GHz or 81 - 86 GHz band
into an FDD arrangement with duplex separation of less than 5 GHz
When the wider channels are needed, e.g. for very high bitrate and high system gain applications (e.g.
employing FSK modulation), then a flexible number of consecutive 250 MHz channels may be
aggregated into FDD channels, as illustrated in Fig. A3.3 for duplex separation of 10 GHz or in Fig. A3.4
for duplex separation of less than 5 GHz.
f19'
86
Formatted:
French (France)
ECC/REC/(05)02
Page 96
f1 (1.25 GHz)
f2
…
fi
71 GHz
f1' (1.25 GHz)
76
f2'
…
fi'
81
86
Figure A3.3: Example of aggregating multiple 250 MHz channels, possibly
alongside with original 250 MHz wide channels
f1 (1.25 GHz)
71/81 GHz
f2
…
fi
f1' (1.25 GHz)
f2'
…
fi'
76/86
Figure A3.4: Example of aggregating multiple 250 MHz channels, possibly
alongside with original 250 MHz wide channels within the single band 71 - 76 or 81
- 86 GHz
ECC/REC/(05)02
Page 97
Annex 4
PRELIMINARY EXAMPLES OF FS TECHNICAL PARAMETERS CONSIDERED IN
FREQUENCY BANDS 71 - 76 / 81 - 86 GHz
This annex provides examples of the key FS radio system parameters, which may be used by
administrations as a guidance for interference evaluation and calculations for frequency sharing with
other services in frequency bands 71 - 76 GHz and 81 - 86 GHz. These parameters should not be
understood as regulatory limits.
The following tables set out the basic parameters for FS system, suited to transmit 1Gbit/s payload but
exploiting different number of 250 MHz channels in 71 - 76 GHz frequency band and/or in 81 - 86 GHz
frequency band, according to the arrangements given in Annexes 1-3 of this recommendation.
Frequency bands
GHz
71 - 76
81 – 86
Channel Bandwidth (MHz)
MHz
250
Payload rate (Gbit/s)
Gbit/s
1
Modulation scheme
128QAM
Receiver Noise bandwidth
MHz
190
Noise Figure @ Antenna Port
dB
12
13
Receiver signal power for BER 10-6
dBm
-56
-55
Antenna gain
dB
50
Maximum output power level @ antenna port
dBm
5
4
Additional feeder losses
dB
0
Antenna radiation pattern
ITU-R F.699 and 1245
Table A4.1: Parameters for 1Gb/s FS link using one 250 MHz channel
Frequency bands
GHz
71 - 76
81 – 86
Channel Bandwidth (MHz)
MHz
500
Payload rate (Gbit/s)
Gbit/s
1
Modulation scheme
16QAM
Receiver Noise bandwidth
MHz
350
Noise Figure @ Antenna Port
dB
12
13
Receiver signal power for BER 10-6
dBm
-61
-60
Antenna gain
dB
50
Maximum output power level @ antenna port
dBm
7-14
6-14
Additional feeder losses
dB
0
Antenna radiation pattern
ITU-R F.699 and 1245
Table A4.2: Parameters for 1Gb/s FS link using two aggregated 250 MHz channels
Frequency bands
Channel Bandwidth (MHz)
Payload rate (Gbit/s)
Modulation scheme
Receiver Noise bandwidth
Noise Figure @ Antenna Port
Receiver signal power for BER 10-6
Antenna gain
Maximum output power level @ antenna port
Additional feeder losses
Antenna radiation pattern
GHz
MHz
Gbit/s
MHz
dB
dBm
dB
dBm
dB
71 - 76
81 – 86
1250
1
FSK
1000
12
-64
13
-63
50
14-20
14-20
0
ITU-R F.699 and 1245
Table A4.3: Parameters for 1Gb/s FS link using five aggregated 250 MHz channels
ECC/REC/(05)02
Page 98
EXAMPLES OF FS EQUIPMENT TO BE USED IN FREQUENCY BANDS 71-76/81-86 GHz
This annex provides details of the key radio system parameters, required for interference
evaluation and calculations for frequency sharing with other services in frequency bands 71-76
GHz and 81-86 GHz.
The following tables set out the basic parameters for FS system, suited to transmit 1Gbit/s
payload but exploiting different number of 250 MHz channels in 71-76 GHz frequency band
and/or in 81-86 GHz frequency band, according to the arrangements given in Annexes 1-3 of
this recommendation.
Frequency bands
GHz
71 - 76
81 – 86
Channel Bandwidth (MHz)
MHz
250
Payload rate (Gbit/s)
Gbit/s
1
Modulation scheme
128QAM
Receiver Noise bandwidth
MHz
190
Noise Figure @ Antenna Port
dB
12
13
Receiver signal power for BER 10-6
dBm
-56
-55
Antenna gain
dB
50
Maximum output power level @ antenna port
dBm
5
4
Estimated maximum output power density
dBm/MHz
-15
-16
Additional feeder losses
dB
0
Antenna radiation pattern
ITU-R F.699 and 1245
Table A4.1: Parameters for 1Gb/s FS link using one 250 MHz channel
Frequency bands
GHz
71 - 76
81 – 86
Channel Bandwidth (MHz)
MHz
500
Payload rate (Gbit/s)
Gbit/s
1
Modulation scheme
16QAM
Receiver Noise bandwidth
MHz
350
Noise Figure @ Antenna Port
dB
12
13
Receiver signal power for BER 10-6
dBm
-61
-60
Antenna gain
dB
50
Maximum output power level @ antenna port
dBm
7
6
Estimated maximum output power density
dBm/MHz
-15
-16
Additional feeder losses
dB
0
Antenna radiation pattern
ITU-R F.699 and 1245
Table A4.2: Parameters for 1Gb/s FS link using two aggregated 250 MHz channels
Frequency bands
Channel Bandwidth (MHz)
Payload rate (Gbit/s)
Modulation scheme
Receiver Noise bandwidth
Noise Figure @ Antenna Port
Receiver signal power for BER 10-6
Antenna gain
Maximum output power level @ antenna port
Estimated maximum output power density
Additional feeder losses
Antenna radiation pattern
GHz
MHz
Gbit/s
MHz
dB
dBm
dB
dBm
dBm/MHz
dB
71 - 76
81 – 86
1250
1
FSK
1000
12
-64
13
-63
50
14
-16
13
-17
0
ITU-R F.699 and 1245
Table A4.3: Parameters for 1Gb/s FS link using five aggregated 250 MHz channels
ECC/REC/(05)02
Page 99
ANNEX 8: ECC Document ECC/REC/(05)02
“USE OF THE 64-66 GHz FREQUENCY BAND FOR FIXED SERVICE”
Recommendation approved by the Working Group "Spectrum Engineering" (SE)
INTRODUCTION
The band 64-66 GHz has been opened for use by fixed service (FS) systems in some European countries.
In particular, this band seems very suitable for very short distance links deployed in dense scenarios. This
recommendation provides an approach for deployment of such FS links in this band.
It is considered that the physical propagation features in this band make possible a lighter licensing
regime than usually used for FS systems, which may include access to spectrum through the use of
flexible frequency arrangements, block (or blocks).
“The choice of the appropriate assignment method remains a decision for national administrations.
considering
a)
that the 64-66 GHz band is allocated to the Fixed Service on a Primary Basis in the European
Common Allocation table and the ITU Radio Regulations (RR);
b) that this band is also allocated to other radiocommunications services on a co-primary basis;
c)
that ITU RR No. 5.547 identifies the 64-66 GHz band for high density applications in the FS;
d) that the 64-66 GHz band is suitable for the deployment of high capacity point-to-point links;
e)
that ETSI has developed TS 102 329 for the FS point-to-point equipment in this frequency band;
f)
that the very short distance links in the 64-66 GHz band call for a light licensing regime;
g) that the atmospheric attenuation in this band may not be sufficient to ensure that a high density of
links can be achieved without suitable management to avoid interference;
h) that the information on fixed links to be deployed in this band will be required to evaluate the impact
of new links on existing links;
i)
that for those administrations wishing to examine in their national assignment process if the
interference threshold has been exceeded, interference criteria need to be defined;
j)
that the level of interference threshold of a victim receiver may be also established based on
ECC/REC 01-05;
ECC/REC/(05)02
Page 100
recommends
1.
that the use of FS in the 64-66 GHz band be limited to point-to-point systems;
2.
that operating frequencies for point-to-point links in this band be assigned or recorded on a link-bylink basis;
3.
that for administrations or operators wishing to determine the impact of new links on existing links,
single and aggregate interference criteria may be derived using guidance given in ECC/REC 01-05.
An example of applying this procedure for FS in the band 64-66 GHz is given in Annex 1;
4.
that administrations who wish to implement a light licensing regime for FS links in this frequency
band may refer to the example provided in Annex 2;
5.
that administrations choose either to allow assignments in this band without a specific channel
arrangement, or establish an arrangement based on simplified frequency slots arrangement as shown
in Annex 3;
6.
that administrations who wish to use the block assignment procedure form blocks consistent with the
frequency slots arrangement given in Annex 3, defining suitable safeguards for interference
avoidance between adjacent blocks.”
ECC/REC/(05)02
Annex 1, Page 101
Annex 1
EXAMPLE OF DERIVATION OF INTERFERENCE CRITERIA
The interference criteria for single entry and aggregate interference can be derived from the
characteristics of the equipment. As an illustration, the following figures in Table A1.1 are taken from the
Annex B (Informative) of ETSI TS 102 329.
Band Î
64 - 66 GHz
Maximum
Nominal
RSL for BER ≤
RSL for BER ≤
Occupied
duplex
10-6 (dBm)
10-8 (dBm)
bandwidth separation
Ð
Ð
(MHz)
(MHz)Ð
(Note 1)
Ð
125
500
850
-61
-59.5
155
620
850
-60
-58.5
622
1250
(Note 2)
-48
-46.5
1250
2000
(Note 2)
-42
-40.5
Note 1: these values are relevant for the 99% power containment for the simplest
spectral efficiency Class 1 (e.g. On-Off-Keying) equipment as defined within EN
302 217-2-1.
Note 2: the occupied bandwidth of 622 and 1250 Mbit/s systems may preclude
duplex operation, and therefore do not have a duplex separation value.
Table A1.1: BER as a function of Receive Signal Level (RSL)
Bit-rate
(Mbit/s)
Ð
In addition the ETSI TS specifies that a co-channel interference with C/I=23 dB should result in RSL
degradation of no more than 1 dB for the above stated BER ≤ 10-6 thresholds, and C/I=19 dB should
result in RSL degradation of no more than 3 dB.
Assuming that this recommendation is relevant to flexible system bandwidth, the triggers for defining
acceptable interference should be defined in terms of absolute interference power density determining an
I/N = - 6 dB for 1 dB degradation (single entry interference) and I/N=-2 dB for 3 dB degradation
(aggregate interference).
This can be derived, for example, from the data in Table A1.1 above with the simple assumption that the
equivalent system noise bandwidth is ~ 30% less than the Occupied Bandwidth (e.g. a OccBw=500 MHz
corresponds to an equivalent NoiseBw ~350 MHz).
The figure of C/I=23 dB for 1dB degradation implies a 6 dB lower system C/N (C/N = 17dB).
Therefore from the -61 dBm figure for the 500 MHz system, it is possible to derive the parameters
necessary for defining the trigger interference power density level:
• Receiver Noise Density: N (dBm/MHz)= -61 -17 – 10log(500*0.7)= - 103.5 dBm/MHz
Therefore in this example the interference criteria for single entry interference could be expressed as
follows:
• Trigger Interference Power Density I (for 1 dB degradation) = -103.5 – 6 = -109.5 dBm/MHz.
Similarly, the interference criteria for aggregate interference in this example could be expressed as
follows:
• Trigger Interference Power Density I (for 3 dB degradation)= -103.5 – 2 = -105.5 dBm/MHz
Note: the possible variation of the percentage ratio between noise bandwidth and the Occupied
Bandwidth, due to different implementation (e.g. roll-off factor), is considered contained within an
additional ±10%, resulting in an error of ~ ± 0.5 dB.
ECC/REC/(05)02
Annex 1, Page 102
Annex 2
EXAMPLE OF TECHNICAL BACKGROUND FOR IMPLEMENTING LIGHT LICENSING
APPROACH FOR FS LINKS IN THE BAND 64-66 GHz
To assist the planning of links, a light licensing approach can be considered. The light licensing regime
does not mean licence exempt use, but rather using a simplified set of conventional licensing mechanisms
and attributes within the scope decided by administration. This planning is delegated to the licensee.
This process at least requires that the Administration records the following set of simple criteria for each
licensed link and makes the data available publicly (perhaps via the internet):
•
Date of application (In order to assign priority);
•
Transmit and receive centre frequencies;
•
Equipment type, specifying relevant transmitter/receiver parameters. It is up to the
administration to define this set of required parameters for recording. (To assist in the
identification of operational parameters, to conduct interference analyses, e.g. following
methodology in Annex 1);
•
Link location (geographic coordinates, height/direction of antenna);
•
The antenna gain and radiation pattern envelope. (e.g. derived from ETSI TS 102 329, which
specifies two alternative envelopes, class 2 and class 3).
Subject to the set of conditions set by the administration, it is left to the operator to conduct any
compatibility studies or coordinate as necessary to ensure that harmful interference is not caused to
existing links registered in the database. For example, an operator wishing to install a new link could
calculate the interference that the new link will create to the existing links in the database. Then it will be
possible to determine whether this new link will interfere with existing links. If so, the new link could be
re-planned to meet the interference requirements of existing links in the database. Otherwise, the new link
may be also co-ordinated with existing operators, who might suffer from the interference.
To assist with the resolution of disputes, licences are issued with a “date of priority”: interference
complaints between licensees may therefore be resolved on the basis of these dates of priority (as with
international assignments).
Radio Systems at 60 GHz and Above
Annex 3
EXAMPLES OF POSSIBLE FREQUENCY SLOT ARRANGEMENTS
IN THE BAND 64.0 – 66.0 GHz
This annex gives examples of frequency slot arrangements for both FDD and TDD applications. The 30
MHz slots for both types of applications can be aggregated to form larger blocks/channels as required by
the national administration.
FDD arrangement
Figure A3.1 shows the basic FDD arrangement consisting of 33 paired 30 MHz slots, which can be
aggregated to form paired FDD channels/blocks consisting of several slots.
10
MHz
64000 64010
33x30 MHz slots
33x30 MHz slots
65000
10
MHz
65990 66000
Figure A3.1: Frequency Division Duplex arrangement (duplex separation: 990 MHz)
TDD arrangement
Figure A3.2 shows the basic TDD arrangement consisting of 66 slots of 30 MHz, which can be
aggregated to form TDD channels/blocks consisting of several slots.
10
MHz
64000 64010
66x30 MHz slots
Figure A3.2: Time Division Duplex arrangement
103
10
MHz
65990 66000
Radio Systems at 60 GHz and Above
ANNEX 9: Responses to Surveys - Regulators
104
Radio Systems at 60 GHz and Above
European National Regulators
ƒ
Austria
Herbert Waxenegger,
Federal Ministry for Transport,
Innovation and Technology,
Ghegastrasse 1A-1030,
Vienna,
Austria.
Phone: +43 1 797 31 42 11.
Fax: +43 1 797 31 42 09
[email protected]
None of the above bands are open yet.
No decision has been taken on the licensing approach should they be opened.
Information will be posted on http://www.bmvit.gv.at
ƒ
Cyprus
Anastasios Elia,
Electronic Communications Officer,
Department of Electronic Communications,
Ministry of Communications and Works,
P.O.Box: 24647,
CY-1302 Nicosia,
Republic of Cyprus.
Tel: +357 22 814875/872,
Fax:+357 22
[email protected]
No-one has applied, nor has authorisation been given, for 60-100GHz operation.
The regulator will review the situation if/when applications are submitted.
ƒ
Czech Republic
Petr Zeman, on behalf of Zdenek Voparil
Director of International Relation Department
Czech Republic.
[email protected]
64-66 GHz : lightly licensed
74-76 GHz : lightly licensed
84-86 GHz : lightly licensed
92-100 GHz : not licensed
ƒ
Denmark
None of the bands are open yet.
If the 65GHz band opens, it is highly possible that a light licensing regime will be
implemented.
105
Radio Systems at 60 GHz and Above
ƒ
Estonia
Signe Maurus
[email protected]
Lada Jostina
Chief Specialist
Radio Frequency Management Dept
[email protected]
All bands are open for fixed link use, and all are on a fully licensed basis.
Further data is available on http://www.sa.ee
ƒ
Finland
Kalle Pikkarainen
Radio Network Specialist, Radio Administration
Finnish Communications Regulatory Authority (FICORA)
tel +358 40 733 44 29
fax +358 9 69 66 410
[email protected]
All the bands are open for Fixed Link use, but there is no detailed channel plan.
All are fully licensed.
Finland follows the work of ECC PT SE19 actively.
Further information is given in http://www.ficora.fi/englanti/radio/Taulukko5.htm
ƒ
France
Mr satellite Deschamps,
ANFR – DPSAI,
78 avenue du Général de Gaulle,
BP400,
94 704 Maisons Alfort,
Cedex FRANCE.
Tel + 33 1 45 18 73 76
[email protected]
The situation is under review, with a policy to be formulated following SE19 decision.
The information will be available on the EFIS web site.
More information about civil use of FS is available from the ART web site:
www.art-telecom.fr or from Mr. Dubreuil ([email protected])
ƒ
Germany
Meik Gawron
Regulatory Office for Posts and Telecommunications
Frequency Assignment for Fixed Wireless Systems
Assistant Head of Section - 226b
[email protected]
Tel: +49-(0)-30-22480-370
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Radio Systems at 60 GHz and Above
None of the bands are yet open and there are no working or operator groups within the
country that are active in these bands. Germany will follow presently emerging CEPT
recommendations as far as possible. It is preferred that 59,3-66 GHz should be fully
licensed. No decision on licensing rules has been taken for the other bands.
59,3-64 GHz:
64-66 GHz:
71-75,5 GHz:
75,5-76 GHz:
81-84 GHz:
84-86 GHz:
92-95 GHz:
95-100 GHz:
ƒ
shared civil and military use
civil use only
shared civil and military use
civil use only
military use only
civil use only
shared civil and military use
military use only
Hungary
Emilia Petras
[email protected]
None of the bands are open.
Policy is set out in two decrees:
Government Dec. No. 346/2004 (XII.22.)Korm.
Minister Dec. No. 35/2004 (XII.28.)IHM
ƒ
Iceland
Hordur Hardarson
Post and Telecom Administration
Tel: +354 510 1500
[email protected]
All the bands are allocated according to ECC standards, but none of the bands are open
yet. In fact there are no links above 26GHz in operation. All fixed links in Iceland
require a licence today.
ƒ
Ireland
Tara Kavanagh,
Comreg,
Ireland.
[email protected]
None of the bands are fully open; however, trial licences are now being issued.
ƒ
Liechtenstein
Fari Hosseini,
Frequency Management
http://www.ak.llv.li/
[email protected]
‘Strategic’ bands are:
64-65 GHz fixed point-to-point links
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Radio Systems at 60 GHz and Above
71-76 GHz fixed point-to-point links; paired with 81-86 GHz
77-81 GHz UWB automotive SRR
81-86 GHz fixed point-to-point links; paired with 71-76 GHz
75,5-76 GHz is allocated to (and used by) amateurs until 2006
ƒ
Lithuania
Mindaugas Zilinskas.
[email protected]
All spectrum is open except 94.0-94.1 GHz.
All bands are lightly licensed.
The Plan for the Use of Radio Frequencies was approved 16 December 2003
Order Number 1V-167
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Luxembourg
Roland Thurmes
Institut Luxembourgeois de Régulation
www.ilr.lu
Tel: + 352 45884524
Fax: + 352 45884588
e-mail: [email protected]
64-66 GHz is already open for fixed links.
59,3-64 GHz will be opened for fixed links at end-2005.
71-76 GHz is not open except for 71-74 GHz harmonised NATO band.
81-86 GHz is not open except for 81-84 GHz harmonised NATO band.
92-100 GHz is not open.
All open bands are fully licensed.
http://www.ilr.etat.lu/freq/legal/index.htm and
http://www.ilr.etat.lu/rtte/interfac/index.html give information.
With the exception of the military allocations, there are no systems in operation.
ƒ
Netherlands
Herman Teinsma,
Ministerie van Economische Zaken,
Agentschap Telecom,
Frequentie Infrastructuren & Systemen,
Postbus 450,
9700 AL Groningen.
T: +3150 –5877201,
F: +3150-5877400,
[email protected]
None of the bands are open. Further information on www.at-ez.nl/nfr/
ƒ
Norway
Stein Gudbjorgsrud,
Head of Planning and Polic/Frequency Department
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Radio Systems at 60 GHz and Above
[email protected]
64-66 GHz open. Currently drafting a text for the band 64-66 GHz. The band will
either be licence-exempt or lightly licensed (in practice licence-exempt with possibility
of registering base stations for protection). For the other bands the NPT has received no
applications. A final decision on which part of the band to allocate for Fixed Links has
therefore not been taken.
ƒ
Poland
Alicja Gawlik,
International Department,
Office of Telecommunications and Post Regulation,
URTiP,
Poland
[email protected]
New contacts are dealing with the enquiry:
Mr. Wikot Sega [email protected] - Director of Frequency Management Resources
of URTiP and Mr. Stanisław Wilkowski [email protected] - Deputy Director
of Frequency Management Resources.
ƒ
Portugal
Luísa Mendes,
Director,
Spectrum Management Department.
Tel. + 351 217212202
Fax. + 351 217211006
e-mail: [email protected]
None of the above bands open.
ƒ
Sweden
Christian Sällström,
National Post & Telecom Agency,
Spectrum Management Department Fixed Radio and Satellite,
Telephone +46 8 678 57 63,
[email protected]
No bands or part bands have been opened.
ƒ
Slovenia
Marjan Trdin
vodja sektorja za radiokomunikacije /head of radiocommunications sector
Stegne 7, POB 418
SI - 1000 Ljubljana,
Slovenija
Tel: + 386 (0)1 583 63 60
Fax: +386 (0)1 511 11 01
[email protected]
109
Radio Systems at 60 GHz and Above
64-66 GHz is open, lightly licensed.
It is planned to open 74-76 GHz and 84-86 GHz, also on a lightly licensed basis.
www.apek.si gives information.
However, the national entry on www.efis.dk/search/general is not up to date.
T/R 22-03 is followed.
ƒ
Switzerland
Ivan Franic,
OFCOM Federal Office of Communications, Frequency Management,
Zukunftstrasse 44,
P.O. Box,
CH-2501 Biel-Bienne,
Phone +41 (0)32 327 55 11,
Direct +41 (0)32 327 57 03,
Fax +41 (0)32 327 56 66,
[email protected]
http://www.bakom.ch
59.3-62 GHz, 64-66 GHz, 71-76GHz, 81-86GHz, 92-94 GHz, 94.1-100 GHz are open.
All of these bands are Fully Licensed, due to sharing with military.
110
Radio Systems at 60 GHz and Above
Non-European National Regulators
Sample data for non-European regulators is shown below. The information is based on
returns to the questionnaires and on website data.
ƒ
Taiwan
Ching-Chich Lin (Mr.)
Director, Department of Radio Spectrum Management,
Directorate General of Telecommunications
At the time of report preparation only an acknowledgement has been received. The
enquiry has been referred to the relevant department; further information is promised.
ƒ
Zambia
Kephas Masiye
[email protected].gov.zm
All the bands in question are free at the moment.
No operator has asked for spectrum in these bands.
ƒ
Philippines
Pricilla F. Demition
Chief, Frequency Management Division
[email protected]
General frequency clearances and/or assignment is done by Frequency Management
Division: [email protected] but licensing is done by various units:
1. Radio Regulations and Licensing Department for private networks, aeronautical
services and maritime services: [email protected]
2. Common Carrier Authorization Department for common carrier services:
[email protected]
3. Broadcast Services Department: [email protected]
Follow up enquiries have been sent accordingly.
ƒ
Japan
Hideto Ikeda
[email protected]
Band 59-66 GHz is available for unlicensed use, with the following specification:
Maximum output power is 10 mW
Maximum antenna gain is 47 dBi
Frequency stability within +/-500 ppm
Maximum Bandwidth is 2.5 GHz
Regulations for Enforcement of the Radio Law, 6-4-2 Specified Low Power Radio
Station, (11) 59-66 GHz band.
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Radio Systems at 60 GHz and Above
ƒ
Singapore
Ms Teo Geok Hoon
(65)6211 1903
[email protected]
The 64-46 GHz bands have been made available by WRC-2000 for high-density
applications in the fixed services (HDFS). The propagation condition and high degree of
frequency reuse enable the use of frequency bands above 30GHz for high-density
deployment of wireless point-to-point and point-to-multipoint systems. These bands are
currently unoccupied and IDA will continue to monitor the developments in this area
and the availability of equipment. In light of the high rainfall in Singapore, IDA
welcomes any interested parties to conduct trial on HDFS systems in Singapore to
investigate the feasibility of deploying such systems. IDA will make available these
bands once there is a demand for use of these bands.
ƒ
Israel
Mr. Meir Ben Basat
Tel. 03-5198231
[email protected]
The enquiry was forwarded to Mr. Basat, who is responsible for telecommunications
services, including Bezeq services, international services and cellular telephony.
At the time of report preparation only an acknowledgement has been received.
ƒ
Canada
Policy is determined by Industry Canada.
http://www.ic.gc.ca/cmb/welcomeic.nsf/ICPages/ContactUs
This is also the government department responsible for the technical standards of
telecommunication and radiocommunication equipment. Follow up enquiries have been
sent accordingly.
Data below is taken from unpublished IEEE802.15-03 input paper (November 2005).
Regulatory Documents
(i) RSS-210, Issue 6, September 2005
(ii) RSS-Gen, Issue 1, September 2005
Canadian and US regulatory requirements are harmonised.
Operating frequency range
57.05 GHz to 64 GHz.
Category I equipment, requiring certification from Industry Canada.
Output Power
2
Average Power Density ≤ 9 μW/cm at 3 m from the antenna aperture
Peak Power Density
Peak Transmitter Output Power
2
≤ 18 μW/cm at 3 m from the antenna aperture
<500 mW, in 100 MHz
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Radio Systems at 60 GHz and Above
Transmitters must have built-in identification such that within any one second interval
of signal transmission, each transmitter with a peak output power equal to or greater
2
than 0.1 mW or a peak power density equal to or greater than 3 nW/cm , as measured 3
meters from the radiating structure, must transmit a transmitter identification at least
once. Each application for equipment authorisation for equipment that will be used
inside a building must declare that the equipment contains the required transmitter
identification feature and must specify a method whereby interested parties can obtain
sufficient information, at no cost, to enable them to fully detect and decode this
transmitter identification information. Upon the completion of decoding, the transmitter
identification data block must provide the following fields:
• Industry Canada certification number, which shall be programmed at the factory.
• Manufacturer's serial number, which shall be programmed at the factory.
• Provision for at least 24 bytes of data relevant to the specific device, which shall be
field programmable.
ƒ
USA – FCC
On February 8 2005, the NTIA announced that the FCC will use an automated webbased licensing process in the 71-76GHz, 81-86 GHz and 92-95 GHz bands, the
commission’s new communications Link Registration System (LRS). Filing can be
completed through one of the three recently appointed FCC Database Managers that
will utilize the new automated Web-based system set up by the National
Telecommunications and Information Agency (NTIA) of the Department of Commerce.
A potential licensee simply has to log onto a secure website managed by any one of the
three database managers. A simple form is completed with proposed end-point
coordinates and frequency band information. The LRS manages all necessary filings
and performs an interference analysis and path coordination, quickly returning a ‘green
light’ indicating that the link is approved or an ‘orange light’ indicating that the
coordination requires more extensive analysis. Ordinarily ‘green light’ approval can be
achieved in less than 30 minutes. The cost of a license is around €100 for 10-years use.
The FCC proposed streamlined and simple licensing and interference protection rules
that will allow business to take full advantage of multi-gigabit wireless technology. The
FCC proposed to allow any individual or company to apply for license to operate 1 to
10 Gbps wireless systems; provide for point-to-point licenses as Part-101 Ruling
extension which assure link integrity; provide for narrow beams (<1°) that allow for
virtually unlimited links in any geographic area.
Past FCC Chairman Michael Powell hailed this licensing concept as revolutionary in
increasing competition and reducing bureaucratic slowdown, and suggested a similar
approach be adopted in all future US rulemakings.
A complete history of the 71-76 and 81-86 GHz filings can be found on the FCC’s
Millimetre Wave 70-80-90 GHz Service website at
http://wireless.fcc.gov/services/millimeterwave
Regulatory Document
(i) CFR Title 47 Part 15.255
(ii) CFR Title 47 Part 15.209
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Radio Systems at 60 GHz and Above
Canadian and US regulatory requirements are harmonized.
All other data as for Canada, above.
Australia
59.4 GHz to 62.9 GHz
Radiocommunications Class Licence 2000.
Output Power
(i) 10 mW (+10 dBm) maximum total peak transmitter power into the antenna
(ii) 150 W (+51.8 dBm) peak maximum EIRP
Above data taken from unpublished IEEE802.15-03 input paper (November 2005).
114
Radio Systems at 60 GHz and Above
ANNEX 10: Responses to Surveys - Industry
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Radio Systems at 60 GHz and Above
E Band Communications
USA based. EBCC was incorporated at the end of 2003. EBCC designs and
manufactures multi-gigabit capacity wireless communication systems based on 7186GHz millimeter-wave radio technology. MMIC) technology that enables EBCC to
manufacturer highest performance wireless systems with 1 to 10 Gbps throughput over
the distances of several miles and availability up to 99.999%. EBCC’s “E-Link” system
operates at E-Band spectrum at 71-76GHz, 81-86GHz, 92-95GHz. The market expects
E-Band to solve last mile access bottleneck problem - connect enterprises to fibre
networks, and enable backhaul of mobile (2.5G/3G) and fixed wireless (Wi-Fi, WiMax) networks. EBCC use’s Northrop Grumman Corporation for its E-Band
Monolithic Microwave Integrated Circuit (MMIC) technology.
Products in the 71-76, 81-86GHz
Carrier-grade availability
Full Duplex data-rate from 1.25 Gbps to 10 Gbps
last mile with distance of 1 to 6 Miles
MMIC based technology Protocol independent
Contact:
Saul Umbrasas, Executive VP of Sales & Marketing
GigaBit
Gigabit Pt-Pt radios now available under $20k.
GigaBeam
Gigabeam was instrumental in opening up the 71-76 GHz and 81-86 GHz bands in the
USA. Gigabeam’s founders provided the initial filing to the FCC to open up this
spectrum, and also chair the Wireless Communications Association’s (an international
wireless industry group) “Above 60 GHz Spectrum Development Committee” who
championed the spectrum release and subsequent rule development through the FCC.
Gigabeam claim many deployments. An example is a metro area system for Manhattan,
New York City, which will be built next year by GigaBeam as a fibre alternative, using
the recently opened spectrum at 71-76GHz and 81-86GHz. It will use a tall building, at
32 Sixth Ave, as its main point of presence. See press releases on www.gigabeam.com.
Gigabeam have also been awarded trial licences in Ireland.
The GigaBeam system can transmit at up to 3Gbps.
Doug Lockie, President,
GigaBeam Corporation
470 Springpark Place, Suite 900
Herndon, VA 20170, USA
+1 (571) 283 6200
[email protected]
www.gigabeam.com
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Radio Systems at 60 GHz and Above
NewLans
NewLans has submitted proposals to the IEEE for a future gigabit Wi-Fi standard, and
is in the shorter term looking to develop proprietary gigabit technologies for 56GHz.
Endwave
Endwave is merchant supplier of RF sub-assemblies, and well-positioned to have
overview of developing manufacturing market.
Whereas the 38GHz band has an installed base of over one million 'ends', the 60GHz
band has probably only 10k ends. 'The market never matured - perhaps the present
lobbying in the USA-FCC will help the cause.' In Europe, are seeing sales in 57,1-58,9
GHz band for micro-cellular BTS - costs are in range USD1000-1500 in current 'low'
volume for E1. Market for GB/s links is very immature - probably only 100's in 2005 at
USD10k per end.
70-80 GHz chipsets are at evaluation stage - around USD1k per end for the chipset.
Price drivers are chipset, packaging, yield and investment recovery. Could lead to
USD2-3k per end total. 'It is essential that lessons are learned from the roadmap of 38
GHz products.' Affordable radios will only be possible with MMIC's. Endwave are
working on active and non-active hybrid MMIC's with 'flipped' chips.
Contact:
Mark Hebeisen, VP Marketing
Huber - Suhner
This Swiss group has a new developed wireless data link SENCITY®Link.
The product version SL60-100-57/64-E-O and will be available for the US market in
compliance with FCC 15.255 part C. The product version SL60-100-57/64-E-O
operates as a data link in the 60 GHz unlicensed band with a data rate of 100 Mbps over
a distance of up to 1 km (3300 ft). operates on QPSK.
Intel
Intel are a merchant supplier of chips, MMICs and RF sub-assemblies. They are
working on CMOS MMICs for up to 100 GHz.
Contact:
Luiz Franca-Neto
Sprint
Sprint are an operator. Sprint's customers 'demand ever-increasing bandwidth to
implement new applications and converge voice and data networks.' He quoted Cisco
as saying that 'fibre only connects 5% of the buildings that will need fibre-speeds; yet
75% 0f these are within one mile of a fibre POP, so could be connected at 60 GHz.
Customers are placing increasd stress on network redundancy, with other drivers being
availability and speed to market.
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Radio Systems at 60 GHz and Above
Contact:
Randy Olsen, Product Manager.
Progress Telecom
Operator in south-east USA. Have 400k miles of fibre and about 200 POPs. Offering
SONET/TDM based services, OC-12 connections. Voice, data and video. Believe the
market needs a 12 month payback, with typical rates around USD7k per month. Users
also want 'carrier grade' service, SNMP management or equivalent, and 99,999%
availability with protection.
Comsearch
USA consultancy, designing and commissioning radio networks (not equipment). Have
insights into FCC decisions at 71-95 GHz.
Terabeam
Radio manufacturer specialising in unlicensed bands. 'Gigalink' radios at 60 GHz and
73-83 GHz. Believe applications will include fibre extension, backhaul, and adding
redundancy to existing dense networks. Say that 60GHz is maturing and affordable but
73-83 GHz kit will always be more expensive than 60 GHz because components are
more difficult and because FCC rules require 1 bit/Hz min whereas 60 GHz has no
limitations.
Bridgewave
60GHz links are approx 25% of cost of E-band links, have natural immunity to
interference, but have shorter range. A killer application could be 'daisy-chaining'
across power pylons to create a POP backbone for broadband ISPs.
GigE 60GHz product:
1000Base-SX
MAC layer transparent
1,25Gbps, full duplex
<50uS latency
~900m range at 99,999% availability (rain zone dependent)
Heavy FEC improves link margins and regenerates data for daisy-chained links.
USD19k per link to end-user (1-off), expected to be much less in high quantities.
BridgeWave Communications recently announced its new FE60 100 Mbps Ethernet
wireless link. The list price for a FE60 link is $14,900.
Contact:
Gregg Levin, Senior VP Product Operations,
Santa Clara,
California.
www.bridgewave.com
Loea Corporation
Loea Corporation is a designer and manufacturer of ultra broadband fixed wireless
telecommunication equipment operating in the upper millimeter wave spectrum from
71.0-86.0GHz. Loea claim to have been the first company to demonstrate a 71.0-
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Radio Systems at 60 GHz and Above
86.0GHz radio system (in 2001) ; first to deploy under Special Temporary Authority
from the FCC (in 2002) ; to have been the key architect of the petition for Rule Making
at the FCC in 2001 ; first to receive NTIA Equipment Certification (in 2003) ; first to
achieve Equipment Certification from the FCC (2005).
L-2500 Transceiver features include:
High all weather availability with 99.999% at 1km in most place in the USA and a
maximum reach of 5km.
Licensed spectrum with efficient licensing scheme to protect against interference
and conserve time and cost.
Ultra high data rates, currently up to 1.25Gbps – full duplex (Gigabit Ethernet)
Plans for 2.5Gbps – full duplex (OC-48) and 10Gbps – full duplex (OC-192 or
10xGigE)
Built-in SNMP device monitoring capabilities and is plug-and-play with standard
network equipment.
Loea’s Corporate headquarters are in San Jose, CA. Loea was incorporated in May
2001 and has had permanent systems deployed since 2002.
Rayawave
Rayawave has products at 60, 70, and 80 GHz currently in trials and available for
purchase. Rayawave is headquartered in San Diego.
http://www.rayawave.com/
Uses "Convolutional Lossless Feeding" design enables a powerful system that can be
deployed at distances up to 5 km and at availabilities of 99.999% or better.
The 70/80 GHz products are the latest in the Rayawave portfolio of high
speed radio products. These products maximize the distance and availability
customers need today.
Introduced in 2003, the 100 and 1250 systems quickly have become the bestselling Rayawave products for Enterprise connectivity for distances up to
1000 meters.
The Rayawave 60 GHz indoor products have been used in factories throughout
the world for high speed flexible connectivity needs.
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Radio Systems at 60 GHz and Above
5
RADIO CHANNEL CHARACTERISATION
5.1 INTRODUCTION
The performance of a radio system is limited by the ability of the receiver to reconstruct
the signal that was transmitted. Limitations to this reconstruction are having sufficient
energy per bit of information {E(b)/No} and that the signal is not too dispersed in time.
The signal available at the receiver is due to energy arriving via both direct and
scattered routes from the transmitter. Within a point-to-point configuration the direct
and indirect paths are a function of clutter in the primary Fresnel zones of the antenna
and due to scattering from antenna side lobes.
The effect of dispersion (frequency selective fading) across the radio channel becomes
more significant as the channel becomes wider. To support Gigabit Ethernet via a radio
channel using low order modulation requires channel bandwidths in the region of 1
GHz.
For a Gigabit Ethernet radio using 4QAM (QPSK) modulation, the channel data rate
including overhead will be approximately 700 M symbols / second. Energy dispersed
between / across symbols will provide self-interference causing the link to fail. This
can be mitigated through the use of adaptive time delay equalisers. Practical equalisers
are able to span approximately 10 symbols. Thus channel echoes with delays of up to
approximately 13n sec can be accommodated.
Without equalisation, 4QAM operation with self-interference levels in the range of 10
dB to 15 dB below the primary signal can be supported with forward error correction.
More spectrally efficient modulation schemes (for example 8PSK or 16QAM) require
further reductions in self-interference to 15 dB to 25 dB below the primary signal.
The channel soundings used here are able to investigate the distribution of the echoes
and to present this as a power-delay profile for the path.
To provoke multi-path behaviour for short paths moderate directivity antennae have
been used. The antennae used here were conical horns with a nominal gain of 20 dBi.
Typical links within the 60 GHz band are using antenna with typically 40 dBi. These
therefore exhibit an angular directivity ten times greater in both elevation and azimuth.
The delay profile for a 100 m path with 20 dBi antennae would therefore scale to a 1000
m path with 40 dBi antennae.
Whilst there are numerous techniques that can be used to measure the channel the use of
an FMCW (frequency modulated continuous wave) signal has advantages in particular
for wide channels. These advantages include the optimum use of the available transmit
power and the high processing gain at the receiver.
5.2 DURHAM 60 GHz CHANNEL SOUNDER
Equipment to translate the operational frequency of the Durham channel sounder into
the 60 GHz band has been designed, assembled and demonstrated to operate.
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Radio Systems at 60 GHz and Above
This is an FMCW channel sounder using a 1040 MHz sweep signal in the range 61 - 62
GHz. This signal is transmitted from one end of the channel and is correlated with an
identical sweep at the receiver to provide an output that can be processed by the existing
signal conditioning and data acquisition system.
The complete channel sounder system consists of a transmitter and a receiver that can
be operated remotely from each other to support a complete link. There is no necessity
to interconnect between the transmitter and the receiver since a Rubidium standard is
used as a reference time base in both units.
The transmitter and receiver equipment is configurable (by changing programming
parameters) to support frequencies in the range from 61 GHz to 67 GHz with the
present hardware configuration.
The concept can be expanded to provide a channel sounder within the range 30 GHz to
110 GHz by replacing the mm-wave hardware elements only.
5.3 CHANNEL SOUNDER CALIBRATION AND VERIFICATION
The channel sounder has been evaluated using two approaches:
Fixed Frequency Evaluation
The performance limits of the 60G Hz up and down converter system has been
evaluated using auxiliary low noise signal sources in place of the 2 GHz chirp signals
that are provided by the core channel sounder.
The result of this portion of the evaluation demonstrates a spurious limit of > 30dB
below the primary signal. The spurious signals that are present are due to low level
feed-through of system clock and other periodic perturbations. These components are
identifiable due to the symmetrical, fixed nature of the signals and could if required be
factored from the data.
Data from the spectrum analyser is included within the description of the hardware in
annex 2.
Frequency Chirp Evaluation
The fixed signal sources are replaced using the chirp waveforms. A configuration with
low multi-path is used for this configuration. To achieve this a short, direct path
between the transmit and receive antennae with no clutter was arranged.
The result of this test was that a sharp primary signal was observed with some
additional spurious signals present at ~ -20 dB below the main signal. These spurious
signals are due to spurious components from the wideband DDFS used in the base
channel sounder that are then further degraded due to the additional X4 multiplication
used by the frequency conversion process.
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Radio Systems at 60 GHz and Above
To confirm that multi-path behaviour could be usefully observed a deliberately multipath rich configuration was contrived. In this configuration the transmit and receive
antennae were each pointed vertically (away from one another) with propagation due to
reflections from the laboratory ceiling structure.
A significant modulation could be observed on the time series data with identifiably
separate path delays on the power - delay profile.
The time series, power delay profile and channel amplitude / frequency plots are
included in within the channel soundings in Annex 1.
5.4 RESULTS OF CHANNEL SOUNDINGS
Refer to Annex 1 for channel sounding data and in-building locations.
(a) In-building
Line of sight (data sets 1 and 2)
For an LOS path within the corridor no significant additional multi-path components
were observed. The measurement was repeated for a small change in the alignment of
the equipment.
Two non line of sight configurations were explored.
For the first NLOS configuration (data set 3), the antenna were deliberately aligned
orthogonally with the transmit antenna pointed to the ceiling. We observed many multipath components with significant energy dispersal across ~ 25 nsec. The signal to noise
ratio remained relatively high such that with equalisation or using delay tolerant forms
of modulation a link should be viable.
In the second NLOS configuration (data set 4) the antennae were aligned in the
horizontal plane. However the transmitter was moved around a corner and was
operated through a pair of glazed doors. Here only one significant multi-path
component was observed with a relative amplitude of -8 dBc at 10 nsec delay. More
significantly however the signal to noise ratio was significantly reduced. It is probable
therefore that a whilst the delay component could be successfully accommodated using
equalisation techniques the link would not be viable due to limited signal to noise ratio.
Contrasting the channel transfer functions, in the first NLOS configuration the signal
level is mostly high across the channel with reductions in level by ~ 10 to 15 dB
occurring in places across the band. In the second approach however, the transmission
is generally at a relatively lower level with a small number of discrete peaks where the
transmission loss was sharply reduced.
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Radio Systems at 60 GHz and Above
(b) Operation from building to building.
In these configurations the transmitter and receiver were each operated within the
building. However the path included transitions from inside to outside the building
through conventional glazed windows.
For the first of these configurations (data set 5) the path was arranged to be
approximately normal to the glazing (within 10 degrees). Operation was through two
glazed units, one close to the transmitter and one close to the receiver. No significant
multi-path components were observed. A reduction in transmission of ~ 10 dB was
observed in the centre of the swept band at around 61.5 GHz.
In the second of these configurations (data set 6) the measurement was along a longer
path at a grazing incidence to the glazing of approximately 45 degrees with a total of
four glazing panels present in the path. A delay component at ~ 10 nsec can be
observed with a relative amplitude of ~ -17 dBc. The attenuation that had previously
been observed around 61.5 GHz was observed to shift further up the band.
(c) Building to building operation.
(For the purpose of this measurement the channel sounder receiver required access to
240V mains power as one of the batteries had been mechanically damaged.)
To provide building to building operation the channel sounder transmitter was powered
from batteries and placed opposite the communications laboratory at a distance of ~ 100
m. This location included building clutter at about 1.5 m below the line of sight path.
In addition the receiver was located relatively close (~ 6 m) to an included corner in the
building. The receiver was operated inside the laboratory with the antenna pointed
through an open window. This is data set (7).
Additionally a second set of data (set 8) was taken with the window closed. This was a
double glazed unit with a set of horizontal Aluminium window blind slats. These were
set in the “open” position.
In both cases discrete multi-path components at ~ -10 dBc at ~ 4 nsec and ~ 11 nsec are
visible. These multi-path components are not explained by reflections directly from the
flat roof in the centre of the path. However, they can be rationalised in terms of
reflection from the adjacent building resulting in an off-axis path into the receiver. This
would not be a significant factor had an antenna more appropriate to a real data link
been utilised due to the higher angular discrimination.
5.5 Conclusions
1. Subject to the use of appropriate directional antennae line of sight paths operated with
low levels of multi-path components both in building and out of building.
2. Operation through glass was demonstrated with little degradation in multi-path
behaviour particularly for near normal incidence. Some smooth frequency selective
behaviour was observable across the frequency band measured.
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Radio Systems at 60 GHz and Above
3. Non line of sight propagation was observed to result in a wide spread of delay
components of near equal amplitude within a single corridor.
4. Non line of sight propagation around an obstacle was observed to occur at discrete
frequencies across the measured band. At other frequencies transmission was
attenuated.
5. For outdoor links the strong reflection from adjacent structures must be considered
when selecting the antennae and the location of the terminal equipment.
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Radio Systems at 60 GHz and Above
Annex 1: Channel sounding measurements in the Durham School of
Engineering.
A brief investigation of channel behaviour was made within the school of engineering at
the University of Durham.
Plan of University of Durham School of Engineering.
The receiver was placed at the location marked (RX) on the plan. The transmitter was
positioned at locations (1) through (6).
Position (1): Corridor, separation 20m, LOS.
Position (2): Repeat of (1) above with minor change of alignment.
Position (3): RX horn turned through 90 degrees (vertical alignment).
Position (4): Operating NLOS (transmitter taken around the corner).
Position (5): Indoor to outdoor to indoor signal normal to the glazing in windows.
Position (6): Indoor to outdoor to indoor signal with 45 degree incidence to the glazing.
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Radio Systems at 60 GHz and Above
Additionally a channel was established between the Communications Lab and a remote
site outside the building. The spacing was ~ 100 m and included a flat roof ~ 1.5 m
below the LOS path.
Measurement (7) is a through the open window.
Measurement (8) is through a closed window with a horizontal slat blind with the slats
in the “open” position.
126
Fig. A1.1.1. Time series position 1
Fig. A1.1.2. Power delay position 1
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Commercial in Confidence
Radio Systems at 60 GHz and Above
Fig. A1.1.3. Channel transfer function for position 1
Fig. A1.2.1. Time series position 2
128
Radio Systems at 60 GHz and Above
Fig. A1.2.2. Power delay position 2
Fig. A1.2.3. Channel transfer function for position 2
129
Radio Systems at 60 GHz and Above
Fig. A1.3.1. Time series position 3
Fig. A1.3.2. Power delay position 3
130
Radio Systems at 60 GHz and Above
Fig. A1.3.3. Channel transfer function for position 3
Fig. A1.4.1. Time series position 4
131
Radio Systems at 60 GHz and Above
Fig. A1.4.2. Power delay position 4
Fig. A1.4.3. Channel transfer function for position 4
132
Radio Systems at 60 GHz and Above
Fig. A1.5.1. Time series position 5
Fig. A1.5.2. Power delay position 5
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Radio Systems at 60 GHz and Above
Fig. A1.5.3. Channel transfer function for position 5
Fig. A1.6.1. Time series position 6
134
Radio Systems at 60 GHz and Above
Fig. A1.6.2. Power delay position 6
Fig. A1.6.3. Channel transfer function for position 6
135
Radio Systems at 60 GHz and Above
Fig. A1.7.1. Time series position 7
Fig. A1.7.2. Power delay position 7
136
Radio Systems at 60 GHz and Above
Fig. A1.7.3. Channel transfer function for position 7
Fig. A1.8.1. Time series position 8
137
Radio Systems at 60 GHz and Above
Fig. A1.8.2. Power delay position 8
Fig. A1.8.3. Channel transfer function for position 8
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Radio Systems at 60 GHz and Above
Annex 2: Description of the channel sounder transmit and receive
hardware developed to support the project.
A2.1
Transmitter Description
Figure A2.1 documents the block diagram of the upgraded transmitter.
This block diagram is relevant both in terms of supporting the 60 GHz channel sounder
and as a practical example of a mm-wave transmitter capable of operation in this
frequency band.
Sounder Transmit Source For 61GHz To 67GHz
Antenna
Sweep
Input
(2GHz +/
200MHz)
X4
TX 60GHz front end
2GHz to 5GHz
Converter
X2
X2
External
Reference
(10MHz)
X2
Second upconverter
Second
Local
Oscillator
Existing design and available
Existing design,more built
Purchased item
New design
X4
External
Reference
(10MHz)
Figure A2.1 RF section of the 60 GHz transmitter
The units that needed new design and construction are highlighted in grey. Units
previously designed for other projects that needed to be built are indicated in yellow.
The remaining items were purchased for the purposes of the project.
To capitalise on the functionality of the existing sounder, both the transmitter and the
receiver use the existing channel sounder linear frequency chirps over the range 1.97
GHz to 2.23 GHz. The new unit comprises three main modules to convert the ~ 2 GHz
chirp to 60 GHz. The first stage converts the output to a range between 5.00 GHz to
5.26 GHz using a previously designed 5.8 GHz up converter. The second stage
translates the frequency sweep to 15 GHz, which is converted to 60 GHz using a
quadruple multiplier. This results in both frequency translation and bandwidth
enhancement.
To realise the three stages of up conversion the following units were designed and built.
A new local oscillator module, which includes a multiplier circuit to convert the 10
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Radio Systems at 60 GHz and Above
MHz reference signal to 40 MHz was designed to phase lock a source operating at 2.56
GHz. This source is subsequently doubled to provide an output at 5.12 GHz.
The multiplication of the reference from 10 MHz to 40 MHz allows the synthesiser
division ratio to be reduced to 40. This reduces the closed loop noise floor by
approximately 7 dB. The reduction in division by four provides a 12 dB enhancement,
however 5 dB is then lost due to the degraded performance of the phase-frequency
divider at the higher comparison frequency. One disadvantage of this approach is that
contiguous 40 MHz steps cannot be achieved. The synthesiser can now support 2560
MHz to 2720 MHz in 40 MHz steps. This module includes a doubler to provide an
output at 5.12 GHz.
The second up converter stage has a frequency doubler for the local oscillator module
output to generate a fixed 10.24 GHz local oscillator. This is subsequently mixed with
the sweep in the range 5.00 GHz to 5.26 GHz to up-convert the chirp to the range 15.24
GHz to 15.50 GHz. This signal is filtered and amplified to provide an input level of
+12 dBm to the final multiplier.
The third stage has a multiplier which is contained in a small aluminium enclosure with
a waveguide interface to provide direct connection to the antenna. A 2m long flexible
cable connects to the up-converter. With an input of 15.24 GHz to 15.50 GHz the
module provides an output of nominally 5 mW (+7 dBm) at 60.96 GHz to 62.00 GHz.
The first three modules above (5 GHz up-converter, 5.12 GHz local oscillator and 15
GHz up-converter) are contained in a 3U 19 inch rack along with the power supply /
micro-controller module.
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Radio Systems at 60 GHz and Above
A2.2
Receiver Description
The block diagram of the receiver is shown in figure A2.2.
This block diagram is relevant both in terms of supporting the 60 GHz channel sounder
and as a practical example of a mm-wave receiver capable of operation in this frequency
band.
Sounder Receive Converter For 61GHz To 67GHz
Sweep
Input
(2GHz +/
200MHz)
X4
Antenna
Port
RX 60GHz
Front End
X2
X2
External
Reference
(10MHz)
X2
60GHz RX driver
Split
External
Reference
(10MHz)
X4
/4
Existing and available
Existing design, more built
Purchased item
External Reference
(10MHz nominal)
New design
Sum
Baseband Output
(30kHz to 300kHz)
Figure A2.2: RF section of the 60 GHz receiver.
The receiver consists of up-converter modules similar to those at the transmitter to
generate a frequency sweep at 61 GHz which is then used to mix with the received
signal. To acquire the data with the existing data acquisition unit (which operates
optimally within the frequency range 30 kHz to 300 kHz) the various units indicated in
grey in the second stage of the receiver were designed and built.
The output from the mixer is the beat signal derived from the swept signal received
from the transmitter and the local swept signal at the receiver. These two signals are
sweeping over identical frequency ranges at the same rate. By off-setting the start point
between the two sweeps an arbitrary beat signal can be derived. In the present
configuration the difference frequency is nominally 12.53 MHz to 12.8 MHz. This
signal is amplified using a two stage amplifier that includes a 5 bit switched attenuator
to provide gain adjustment over a 31 dB range. The design has a measured noise figure
of 3 dB and a 1 dB compression point of +12 dBm. Since the design uses feedback the
distortion is very low up to the level at which output clipping occurs.
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Radio Systems at 60 GHz and Above
The output of the amplifier is then down-converted to provide a beat signal in the range
30 kHz to 300 kHz. This signal is then processed by the existing sounder signal
conditioning and data acquisition units.
The down-converter includes a band-pass filter at 12.5 MHz to provide discrimination
of the image frequency at 7.5 MHz due to down conversion to ~2.5 MHz (2.53 MHz to
2.8 MHz) using a 10 MHz local signal. The signals at 2.53 MHz to 2.8 MHz are then
converted to base-band (30 kHz to 300 kHz) using a local signal at 2.5 MHz.
Since it is impractical to suppress the image frequency using filter techniques, a singlesideband conversion has been implemented. This requires a local oscillator signal that
provides signals that are precisely in quadrature plus a broad band 90 degree phase shift
network operating over the base-band frequency range.
The signal to be down-converted is provided to two down-conversion mixers each
operated from the local oscillator with 90 degree difference between the two channels.
The quadrature local oscillator signals are derived using a four phase divider with a 10
MHz input to provide outputs at 2.5 MHz. This is implemented in fast CMOS logic.
The phase difference was measured to be less than 0.1 degree from 90 degrees.
The outputs from these two mixers are then processed using a cascade of all-pass delay
networks to provide a further differential phase shift of 90 degrees across the required
base-band range (30 kHz to 300 kHz). A four plus four section design with a design
ripple of 0.0075 degree has been implemented. Using 1% tolerance capacitors and
0.1% tolerance resistors an unwanted sideband rejection of 50 dB has been
demonstrated [see figure A2.3].
The appropriate sideband can be selected by either adding or subtracting the two signals
from the outputs of the broadband phase shift networks. (Subtraction is used in this
case to select the upper sideband). The wanted sideband is reinforced and the unwanted
sideband is cancelled.
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Radio Systems at 60 GHz and Above
SSB Down-Converter Response
10
0
Relative Response (dBc)
-10
-20
-30
-40
-50
SSB response
-60
12.00
12.10
12.20
12.30
12.40
-70
12.50
12.60
12.70
12.80
12.90
13.00
Frequency (MHz)
Figure A2.3: Sideband discrimination of the SSB down-converter.
A2.3
Converter Evaluation
It is necessary to characterise the equipment to confirm that it is capable of performing
the measurements for which it has been designed.
To characterise the system a pair of low phase noise test sources have been designed
and assembled to allow an end-to-end noise measurement of the system.
The measurements that have been performed provide confidence that the system is
capable of observing delay components down to a relative level of ~ –20 dBc. This is
sufficient to confirm that low order modulation (BPSK, 2-FSK, 3-FSK, 4-QAM and 8PSK) could be supported by the channel with no equalisation.
Note. The 60 GHz converter modules provide a measurement limit of > 30 dBc.
However, due to the multiplication (X4) of the basic sweep signal from the DDFS the
spurious outputs from this source are degraded by 12 dB. This is responsible for the
uncorrected measurement limit of the channel sounder. Since these distortion products
occur at a fixed point in the delay spectrum they could if required be identified and
factored from the results.
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Radio Systems at 60 GHz and Above
Figure A2.4: Converter CW response 500 kHz span
The delay spectrum (of figures A2.4 to A2.7) demonstrates a spurious limit of > 30 dB
for the 60 GHz conversion process. The discrete tones are due to system clock and
other repetitive interference sources within the frequency conversion system. (Systemic
interference of this type produces spurious components that are symmetric around the
primary signal).
Figure A2.5: Converter CW response 50 kHz span
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Radio Systems at 60 GHz and Above
Figure A2.6: Converter CW response 5 kHz span
Figure A2.7: Converter CW response 500 Hz span
At the transmitter a low-phase noise synthesised signal source at 2.000 GHz was used in
place of the swept (2 GHz) signal. At the receiver a low-noise synthesised signal source
at 2.003333 GHz was used in place of the swept signal. This provided a beat note of
13.333 MHz at the output of the 60 GHz mixer. This was down converted to 250 kHz
using the single sideband down-converter.
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Radio Systems at 60 GHz and Above
The effective noise bandwidth of the signal processing is 250 Hz ( the FFT bin size).
The measured data demonstrates a general noise level of ~ -45 dBc within a 300 Hz
bandwidth (closest spectrum analyser bandwidth) with discrete spurious signals at a
level of -30 dBc. These discrete spurious signals are due to low level contamination of
the power supplies due to power supply switching noise and system reference clocks.
A2.4
Initial channel sounder measurement
An initial test was performed by setting up the transmitter and receiver to sweep over a
1040 MHz bandwidth with a 250 Hz waveform repetition frequency. This provides a
sweep rate of 2.6*10E11 Hz/second. The units were separated by approximately 240
cm with 20 dBi gain conical horn antennas.
A2.4.1 Investigation of ideal “good” channel behaviour
For the first measurement the antennas were aligned to provide minimum levels of
multi-path propagation. Figure A2.8 displays the acquired data for a single sweep.
Figure A2.8: Sounder time-series data.
The limited low frequency envelope modulation to the beat frequency indicates the lack
of significant multi-path components.
Figure A2.9. 61 GHz delay profile (Fourier transform of the time series data).
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Radio Systems at 60 GHz and Above
Figure A2.10. Channel transfer function.
A2.4.2 Investigation of ideal “multi-path rich” channel.
To contrast the “ideal good” channel behaviour the system was reconfigured to provide
a high level of multi-path behaviour. This arrangement had both the transmit and
receive sources separated by ~ 240 cm with each pointing vertically to the ceiling ~ 200
cm above the antennae.
Figure A2.11. Time series data for NLOS path.
The heavy envelope modulation is indicative of significant frequency selective
behaviour due to multi-path propagation.
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Radio Systems at 60 GHz and Above
Figure A2.12. Delay profile for 61 GHz NLOS path.
Figure A2.13. Channel transfer function for 61 GHz NLOS path.
From these two sets of measurements we can conclude that multi-path propagation this
is observed by the channel sounder.
Sounder Resolution
A sample rate of 1Msample / second provides 4096 samples per sweep (4000 expanded
to 4096). Each “bin” for the processed data output from the Fourier transform process
is therefore:
1E6 / 4096 = 244 Hz wide.
The sweep rate is 250 sweeps / second * 1040E6 Hz / sweep = 2.6E11 Hz / second
Thus the ideal range resolution is:
244Hz / 2.6E11 Hz / second = 938 psec.
The effect of the Hamming windowing of the data reduces this to ~1.2 nsec in practice.
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Radio Systems at 60 GHz and Above
A2.5
Hardware Photographs
Figure A2.14. 60 GHz RX front end.
The 60 GHz multiplier and mixer are located in the centre of the box lid.
The base-band amplifier is the lower printed circuit board. The single sideband downconverter is the upper printed circuit board.
Figure A2.15: 60 GHz TX front end.
Connections on the left are for power and RF stimulus at ¼ of the output frequency.
The multiplier is attached to the centre of the lid of the box to provide a heat-sink.
Subsequently an additional heat-sink was provided on the rear of the enclosure to
improve power dissipation and to reduce the operating temperature.
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Radio Systems at 60 GHz and Above
Figure A2.16: Horn antenna (20 dBi on left, 10 dBi on right).
Figure A2.17: Transmit driver
Original modules are the power supply / controller (left half) and the 5.8 GHz upconverter (extreme right).
New modules are 2nd up-converter (with cables) and 2nd local oscillator next unit right.
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Radio Systems at 60 GHz and Above
Figure A2.18: Receiver driver (internal)
2 GHz to 5.8 GHz up-converter is on front panel. 2nd local oscillator is on rear panel. 10
MHz to 40 MHz multiplier and -12V PSU are on the right panel (as viewed). Other
microwave components are on the left panel.
Acknowledgements
Roger Lewenz and Nima Razavi provided assistance with the final assembly of the rack
modules, measurements and data processing.
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Radio Systems at 60 GHz and Above
6
THE SPECTRUM EFFICIENCY OF FREQUENCY/POWER
CONTROL
There is currently increasing pressure to make more efficient use of the radio spectrum,
and to open up frequency bands where it is possible to provide the large bandwidths
required for the next generations of radio systems such as mobile internet. The 60 GHz
band is currently under-utilised, mainly due to the difficulties associated with
compensating for the affects of rain attenuation experienced by frequencies in that
range.
Adaptive Transmit Power Control (ATPC) has been proposed in the literature as a
promising technique for opening up higher frequencies to commercial exploitation. It
can also be used at lower frequencies to reduce the transmit power used during clear sky
conditions and compensating for fading on a dB by dB basis. This would enable an
increase in the rate of frequency re-use, and hence an improved spectral efficiency.
Radio systems operating at 60GHz and above are not currently efficient or economical
due to the large fade margins required to compensate for the intermittent yet dramatic
effects of rain fading. ATPC and Dynamic Frequency Diversity (DFD), are fade
mitigation techniques which can help to make systems at these frequencies more
economical, and hence more open to commercial exploitation.
6.1 ATPC (Adaptive Transmit Power Control)
6.1.1 ATPC operation
The basic principle for ATPC is quite simple. In cases where rain fading occurs on the
radio path, it involves increasing the transmit power in order to be able to compensate
for the fade. Given a reliable power control system, it is possible to reduce the fixed
fade margin during clear sky conditions (i.e. no fading), thereby improving the rate of
frequency reuse and link packing density in the geographical area of the link. This is
because lower fade margins use less transmit power, which lessens the interference on
adjacent links.
ATPC attempts to maintain the carrier to noise ratio (CNR) at the receiver of the
terrestrial P-P link at the required level to achieve the desired quality of service (QoS)
or bit error rate (BER), as appropriate. The CNR should always be greater or equal to
the minimum CNR value calculated from detailed link power budgets. The basic
operation of ATPC is illustrated in figure 6.1 [1].
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Radio Systems at 60 GHz and Above
CNR(t)
ε
R
Clear-Sky CNR
Min CNR
Time
(a)
ATPC(t)
R1
R2
R3
R
Time
(b)
Resultant CNR(t) with ATPC
ε
Clear-Sky CNR
Min CNR
outage
Time
(c)
Figure 6.1: Principle of ATPC
Let us assume that the system has been designed to achieve an unfaded CNR that is ε
dB greater than the minimum CNR. Whenever the CNR drops below the minimum
CNR (green line in figure 6.1(a)), the link will be in outage if no action is taken. Hence
ATPC is required to compensate for the link attenuation so that the QoS can be
maintained as shown in figure 6.2(b). The transmit power is boosted on a dB per dB
basis so as to compensate for the impact of the fade. This has the effect of keeping the
CNR at its minimum value (see regions R1 and R3 in figure 6.1).
In practice, however, the dynamic range of the ATPC system will be limited to R dB.
This limitation implies that whenever the attenuation exceeds ε + R dB with respect to
the unfaded level, the fades will not be compensated. The resulting CNR, shown in area
R2 of figure 6.1 (c), will drop below its minimum acceptable value and the system will
be in outage.
In comparison with a non-ATPC system, the margin ε + R dB corresponds with the
rain fade margin as defined in Ofcom’s frequency assignment methodology, and as is
shown in figure 6.2.
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Radio Systems at 60 GHz and Above
CNR(t)
Clear-Sky CNR
εf, fixed power margin
R
2
Min CNR
Time
Figure 6.2: Non-ATPC System with a Fixed Power Margin
6.1.2 Previous studies
The final report of an Ofcom study titled “Study to assess the impact of fade mitigation
techniques in bands above 20 GHz” [1] indicated that there are spectrum gains to made
as a result of introduction of ATPC in P-P fixed service bands, especially those
operating at frequencies where rain is a significant attenuator. However, this study was
limited in scope, dealing only with a simplified scenario of two parallel links in the 18
GHz band, separated by distances of ~ 1-10km.
Richardson et al, [2004] conclude that, for their scenario of two parallel links of length
5km, separated by distances of ~5km:
•
ATPC allows a link to operate with a lower Tx power under clear sky
conditions.
•
Rain fading is highly correlated over the scenario area (~ 20-100 km²) for the 18
GHz band. Therefore, during rain events all paths are likely to fade, indicating
that interference levels from an ATPC enabled link will stay at approximately
the same level at the victim receiver even when the ATPC link is transmitting at
full power.
•
For the ATPC-only scenario the separation distance can be reduced with the
amount of reduction being dependant on the choice of the Tx power margin.
•
For mixed scenarios the separation distance can be similarly reduced without
adversely affecting the performance of the non-ATPC link. However, the ATPC
link will suffer a corresponding increase in interference power at its receiver and
this must be compensated for when deploying the link by, for example,
increasing the interference margin.
•
For the area covered by the scenario, theoretical and simulation results
considering the space-time properties of rain attenuation indicate that worst-case
interference generated by an ATPC link is obtained during clear-sky conditions.
•
Received signal level (RSL) is the preferred fade detection mechanism as it is
only affected by rain fading. BER-led ATPC would result in an increase in Tx
power as a response to increased interference, which could lead to a “domino
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Radio Systems at 60 GHz and Above
effect” where all links end up transmitting at their highest power, negating any
spectrum gains.
•
Management of ATPC links can be implemented in a distributed manner where
each link operates independently.
•
Benefits will arise to both individual operators (operational cost savings) and the
industry as a whole due to the potential for reduced co-ordination distances and
gains in spectrum utilisation.
Ofcom is currently funding a project entitled “Impact of introducing Automatic
Transmit Power Control in P-P Fixed Service systems operating in bands above 13
GHz”. The outputs of the project are software tools to re -plan existing frequency plans,
subject to a number of assumptions on the mix of ATPC and non-ATPC links and the
type of ATPC in use, and evaluating the system performance by direct comparison
between all-ATPC plans, non-ATPC plans and mixed plans. The project investigates in
greater detail the impact of implementing ATPC in the 38 GHz band, using as a base the
entire link planning database in that band. The final report of the project will give the
results and conclusions in greater detail.
This report will expand on the work done in the previous two studies to take into
account the impact of implementing ATPC in bands above 60 GHz.
6.2 DFD (Dynamic Frequency Diversity)
6.2.1 DFD operation
Dynamic Frequency Diversity (DFD) should not to be confused with DFS (dynamic
frequency selection).
DFD involves using two co-located links, one at millimetre wave frequency and the
other as a free space optical (FSO) link. The FSO link is not affected by rain, but is
badly attenuated by fog, while the millimetre wave link is badly attenuated by rain, but
not affected by fog. Switching between the millimetre wave link and the FSO link
allows greater availability to be ahcieved than using one alone. Dual systems such as
these potentially allow practical and economic operation of radio systems at millimetre
wave frequencies.
DFS operates by dynamically switching between radio channels in a single band.
6.3 RAIN FIELD CORRELATION
Rain is the dominant attenuator at radio frequencies above ~10 GHz. ATPC is
designed to compensate for rain fading. DFD can be implemented to compensate for
the attenuating effects of fog or rain, depending on the operator’s choice of which link
is to be the primary and which the secondary.
The best case scenario for ATPC is that the rain fading is completely correlated across
the entire area of interest; i.e. the wanted and the unwanted links will be equally badly
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Radio Systems at 60 GHz and Above
affected by the rain field. If this is the case, then the problem then reduces to clear sky
case.
The worst case scenario for ATPC is if the rain fading is completely uncorrelated
across the entire area of interest; i.e. rain rate is at a maximum on the wanted link,
while the unwanted link is not attenuated at all.
Millimetre wave communications applications typically need to operate over short
paths (<10km), though interference paths may be longer. Hence there is a need to
investigate the spatial autocorrelation function of rain and determine at what distances
rain fields can be considered to be correlated or de-correlated.
6.3.1 Spatial and temporal analysis of meteorological radar data: Data
description
The rainfall rate contours analysed in this research have been obtained by means of the
Chilbolton Advanced Meteorological Radar (CAMRa), which is located in Hampshire
in the south of England, at the latitude 51˚ 9' North and the longitude 1˚ 26' West. The
climate is temperate maritime, with an average annual rain rate exceeded 0.01% of the
time of approximately 22.5 mm/hr. The radar is a 25 m steerable antenna, equipped with
a 3GHz Doppler-Polarization radar, and has an operational range of 100 km, and a beam
width of 0.25˚. To avoid reflections from ground clutter, maps of the rain rate field near
the ground were produced by scanning with an inclination of 1.2˚. These maps are
produced on a polar grid, with a range resolution of 300m and an angular resolution of
0.3˚. The number of maps produced in a given time period is dependent on the total
angle scanned. The radar has a maximum angular velocity of 1˚/second.
The radar scans were interpolated onto a square Cartesian grid, with a grid spacing of
300m and a side length of 56.4 km. Each grid contains 35344 data points ( 188 2 )
covering more than 3100 km². The grids are separated in time by approximately 2
minutes.
6.3.2 Spatial autocorrelation of measured rain fields
Measurements [2] have shown that it can be assumed that the spatial correlation of rain
falls off exponentially with distance for the first 50 km or so [see also 1]. The decorrelation for rain rate for large distances (up to 1000 km) and multiple stations was
presented by Barbalisica et al, [3], using a very large rain gauge database covering the
entire Italian territory. They have shown that for distances greater than 50 km the falloff of spatial correlation with distance slows, though there can be jumps due to a
recoupling effect resulting from the presence of another separate rainy event occurring
at far distances at the same time. For their data, it was reported that statistical
independence was reached for distances between sites greater than 800 km. However,
for systems operating at 60 GHz and above, we can consider the spatial correlation of
rain fields to fall off exponentially with distance, without being too concerned about the
limits where this assumption breaks down.
Rain events can be subdivided into types according to the characteristic behaviour of the
rain fields. Stratiform events tend to occur in the winter and spring months, and are
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Radio Systems at 60 GHz and Above
events where it rains at low intensity for long periods (several hours). Stratiform events
tend to be very widespread, and in terms of meteorological radar measurements are
characterised by the presence of a bright band in the vertical scans. (The bright band
occurs at the melting layer, the height above the ground where the temperature is such
that liquid water and ice coexist. Below the melting layer, all the atmospheric water is in
the form of rain drops.) Convective events tend to occur in the summer and early
autumn months. They are characterised by their turbulent nature (i.e. there is no bright
band in the vertical radar scans). Convective events are short-lived and intense rain
events, which are also geographically localised, covering areas of only tens of km2.
Frontal events are rare and are generally mixtures of stratiform and convective events.
For example, in the frontal event investigated here, a band of stratiform rain with
convective rain cells embedded in it was pushed across the country by a strong wind.
Figures 6.3a, 6.3b and 6.3c show the two-dimensional spatial autocorrelation function
calculated for three different types of event measured by CAMRa, convective, frontal
and stratiform respectively. As can be seen, the correlation coefficient falls off quickly
with distance in all three cases, approaching zero for distances of around 180 pixels
(corresponding to 54 km). This agrees well with the general assumption mentioned
above.
A key point is the differences in behaviour of the autocorrelation function for the
different event types. As can be seen, the autocorrelation function for the convective
event falls off more quickly with distance than the autocorrelation function for the
stratiform event. The autocorrelation function for the frontal event appears as a mixture
between the two others. This is due to the phenomenological behaviour of the different
types of rain event.
157
Figure 6.3a: Spatial autocorrelation for a convective event
Figure 6.3b: Spatial autocorrelation for a frontal event
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Commercial in Confidence
Radio Systems at 60 GHz and Above
Figure 6.3c: Spatial autocorrelation for a stratiform event
A better view of the fall-off of spatial correlation with distance can be seen in figures
6.4a, 6.4b and 6.4c. In these figures, radial cross-sections have been taken from the centre
points of the auto-correlation plots at different angles to the edges.
Figure 6.4a: Radial sections through the spatial autocorrelation for a convective event
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Radio Systems at 60 GHz and Above
Figure 6.4b: Radial sections through the spatial autocorrelation for a frontal event
160
Radio Systems at 60 GHz and Above
Figure 6.4c: Radial sections through the spatial autocorrelation for a stratiform event
These figures show that the fall-off of autocorrelation coefficient with distance can be
approximated by an exponential decay, as described in the literature, though as shown
before, the rate of that decay is steeper in the convective rain fields than in the
stratiform and frontal fields.
For distances of 0 to 40 pixels (0 to 12 km) the correlation factor varies from 1 to ~0.7.
As millimetre wave applications need to operate over short paths (<10km), we can
effectively consider the rain field to be correlated over that distance. However, the rain
isn’t completely correlated over those distances, hence we introduce an exponential rain
model to give an indication of a more realistic worst case scenario given the presence of
rain.
6.3.3 Exponential rain model
The worst case situation, that the rain field is completely decorrelated, doesn’t happen
over the size of areas of interest for frequencies above 60 GHz. Hence a more realistic
worst case rain scenario is needed.
We assume that the maximum rain rate is occurring on the wanted link, centred on the
receiver, and that the rain rate falls exponentially with distance away from this point.
Strictly speaking, it’s the correlation coefficient that falls exponentially with distance,
but having the rain rate falling in line with the correlation coefficient gives us a more
realistic worst case scenario.
The formula used was R ( x) = R0 e − λx where R(x) is the rain rate as a function of the
distance from the centre point of the rain cell, R0 is the rain rate value at the centre of
the rain cell and was set to 25 mm/hr. The decay constant λ was 1/25.
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Radio Systems at 60 GHz and Above
Figure 6.5 shows the rain attenuation using the exponential rain model on an unwanted
link for a range of frequencies and different link lengths. As the unwanted link length
increases, the rain rate per kilometre decreases, hence the curve.
Figure 6.5: Rain attenuation from the exponential rain model as a function of link
length and frequency.
6.4 LINK TOPOLOGIES
The link budget for a link is given by:
PR = PT − AT − AR + GT + G R − 92.4 − 20 ⋅ log10 (d [ km ] ) − 20 ⋅ log10 ( f [ GHz ] ) − Aa − Ar( 0.01)
where:
PR = Received Power (dBm)
PT = Transmitted Power (dBm)
AT , AR = Tx / Rx Feeder Losses (dB)
GT , G R = Tx / Rx Antenna Gain (dBi)
d [km ] = Link Length (km)
f [GHz ] = Link Frequency (GHz)
Aa = Atmospheric Attenuation (dB)
Ar( 0.01) = Attenuation due to rain (dB)
Figure 6.6 shows the antenna gain as a function of angle, for a frequency of 60GHz. As
can be seen, the antenna gain is at a peak when then transmitter and receiver are aligned
(i.e. at an angle of 0 degrees). The antenna gain falls off rapidly with increased
deviation from the correct alignment.
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Radio Systems at 60 GHz and Above
Figure 6.6: Antenna gain as a function of angle.
The scenario used in this study is shown in figure 6.7. It consists of two links operating
at the same frequency and transmit power. The wanted link has a fixed length of 0.5 km
and the transmit and receive angle of the unwanted link and the length of the unwanted
link are variable.
TX
(unwanted)
χ – transmit angle
Unwanted link length s (km)
receive angle -θ
RX
(wanted)
TX
(wanted)
Wanted link length d (km)
Figure 6.7: Schematic diagram of a pair of links at the same frequency, but with
variable length, transmit and receive angles of the unwanted path
The wanted to unwanted signal ratio is commonly used in the TFAC (Technical
Frequency Assignment Criteria) to determine whether or not a proposed new link can be
163
Radio Systems at 60 GHz and Above
assigned. For the scenarios investigated in this report, where we are looking at two links
operating with the same transmit and receive hardware, and transmitting at the same
power levels and frequency, the W/U is given as follows:
W / U = Aunwanted − Awanted + 2G (0) − G (θ ) − G ( χ ) − Acls _ wanted + Acls _ unwanted
− Arain _ wanted + Arain _ unwanted
where
Aunwanted = Attenuation on the unwanted link due to Tx and Rx feeder losses (dB)
Awanted = Attenuation on the wanted link due to Tx and Rx feeder losses (dB)
G () = Antenna gain as a function of incidence angle (dBi)
Acls _ unwanted = Attenuation on the unwanted link due to clear sky attenuation (dB)
Acls _ wanted = Attenuation on the wanted link due to clear sky attenuation (dB)
Arain _ unwanted = Attenuation on the unwanted link due to rain attenuation (dB)
Arain _ wanted = Attenuation on the wanted link due to rain attenuation (dB)
Figure 6.8 shows the W/U level as a function of the frequency of the links and the
length of the unwanted link in clear sky conditions for the worst case scenario of the
unwanted link being co-linear with the wanted link. As can be seen, as the unwanted
link length increases, there is a gradual increase of W/U. In terms of frequency, this
increase is more dramatic in the band around 60 GHz, but is a similar rate of increase at
100 GHz as at 50 GHz. Figure 6.9 shows the same graph, but in close up for distances
of 0 to 10km.
Figure 6.8: W/U level as a function of the frequency of the links and the length of the
unwanted link in clear sky conditions
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Radio Systems at 60 GHz and Above
Figure 6.9: W/U level as a function of the frequency of the links and the length of the
unwanted link in clear sky conditions. Close up for distances between 0 and 10 km.
Similarly, figure 6.10 shows the W/U level as a function of the frequency of the links
and the length of the unwanted link during rainy conditions for the same unwanted
transmit and receive angle. As in the clear sky case, as the unwanted link length
increases, there is a gradual increase of W/U, which is more pronounced for frequencies
in the band around 60 GHz. In the rainy case, generally as the frequency of the link
increases (with the exception of the 60GHz band), the W/U ratio also increases. Figure
6.11 shows the same graph, but in close up for distances of 0 to 10km.
Figure 6.10: W/U level as a function of the frequency of the links and the length of the
unwanted link in rainy conditions (exponential rain model)
165
Radio Systems at 60 GHz and Above
Figure 6.11: W/U level as a function of the frequency of the links and the length of the
unwanted link in rainy conditions (exponential rain model). Close up for distances
between 0 and 10 km.
A direct comparison of figures 6.9 and 6.11 indicates that the W/U is generally higher
during rain than during clear sky conditions. This is because the longer the unwanted
radio path, the more attenuation it suffers, as seen in figure 6.5. This suggests that clear
sky is in fact the worst case for this scenario, and that designing a system with enough
margin to cope with clear air effects, which uses ATPC to combat rain fading on the
wanted link, will be the most spectrally efficient.
Similar results are seen for different unwanted transmit and receive angles. An example
is shown for θ and χ both set to 15 degrees in figure 6.12 and 6.13.
166
Radio Systems at 60 GHz and Above
Figure 6.12: W/U level as a function of the frequency of the links and the length of the
unwanted link in clear sky conditions
Figure 6.13: W/U level as a function of the frequency of the links and the length of the
unwanted link in rainy conditions (exponential rain model)
Figure 6.14 shows the variation of W/U with the increase of receive angle for a set
unwanted path length of 10km and an unwanted transmit angle of 0 degrees (i.e. the
unwanted link is in the same line as the wanted link). Figure 6.15 shows the same
variables, but with an unwanted transmit angle of 90 degrees. In both graphs, the effects
of the exponential rain model are included.
167
Radio Systems at 60 GHz and Above
Figure 6.14 showing the variation of W/U with the increase of receive angle for a set
unwanted path length of 10km and a unwanted transmit angle of 0 degrees (exponential
model for rain)
Figure 6.15 showing the variation of W/U with the increase of receive angle for a set
unwanted path length of 10km and a unwanted transmit angle of 90 degrees
(exponential model for rain)
For both figures 6.14 and 6.15 the curves are similar; the only difference is that the W/U
is higher when the unwanted transmit angle is higher.
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Radio Systems at 60 GHz and Above
6.5 SPECTRUM EFFICIENCY
IMPLEMENTING ATPC
GAINS
RESULTING
FROM
As mentioned earlier, previous and on-going studies have investigated the spectrum
efficiency benefits of implementing ATPC in bands up to 38 GHz, primarily
concentrating on fixed terrestrial links. In higher frequency bands the situation is
complicated by the 10GHz band around 60 GHz, where the oxygen absorption band
suppresses long distance transmissions, hence enabling a reduction of the frequency
reuse distance to as little as 1 km in some situations.
The link layout scenario presented in this report is by necessity simplistic, dealing as it
does with only two links and a simplified rain model. Still the results suggest that ATPC
has the potential to improve spectrum efficiency in bands above 60GHz. As a worse
W/U is predicted in clear sky than in rain, designing a link to clear sky specifications
and compensating for rain fading dynamically on a dB by dB basis will minimise the
separation distance between the links.
Further study, similar to that already done in the 38 GHz band (as mentioned in section
XX) is recommended to further quantify the potential gains for more realistic rain and
link layout topologies.
6.6 SPECTRUM EFFICIENCY GAINS RESULTING FROM
IMPLEMENTING DFD
The next section in this report shows how the joint exceedance probabilities of a
millimetre wave link and a free space optical link in tandem indicate that deep fading
does not happen on both links simultaneously. FSO links are badly affected by fog, and
are insensitive to rain, while radio links above 10 GHz are affected by rain but are
insensitive to cloud. Hence when the radio path is badly attenuated, the FSO path is not
attenuated, and vice versa.
From measurements made at Chilbolton on the 500m range (as mentioned in Section
5.1) to achieve an availability of 99.99% on a FSO link, a fade margin of over 40 dB is
required. For a radio link at 57 GHz, a fade margin of ~10 dB would be needed for the
same availability. A combined system using both a FSO link and a radio link at 57 GHz
would require a 2 dB fade margin on the radio link and a 10 dB fade margin for the FSO
link, which is a substantial reduction.
As with ATPC, reducing the transmit power of a radio link during clear sky conditions
will improve the rate of frequency reuse within a given geographical area. At this time,
effective and economic utilisation of the bands above 60 GHz is believed to be a higher
priority, as these frequencies are not commonly used.
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Radio Systems at 60 GHz and Above
6.7 REFERENCES
1
Richardson, K.W., Thomas, D.W., Callaghan, S.A., Gremont, B. “Study to
assess the impact of fade mitigation techniques in bands above 20 GHz: Final
report”. Project report for Ofcom, 2004
2
Paraboni, A., Masini, G., Riva, C., “The spatial structure of rain and its impact
on the design of advanced TLC systems” pp.169-172, Proc. Fourth Ka Band
Utilization Conf. Venice, Italy, Nov 2-4, 1998
3
Barbaliscia, F., Ravaioli, G., Paraboni, A., “Characteristics of the spatial
statistical dependence of rainfall rate over large areas” IEEE Trans. on Ant. and
Prop., vol. 40, n.1, pp8-12, 1992
170
Radio Systems at 60 GHz and Above
7
DUAL MILLIMETRE WAVE/FSO SYSTEMS
7.1 INTRODUCTION
Frequency bands above 60 GHz suffer severely from rain attenuation. This will put
constraints upon the length or availability of links. Free Space Optical (FSO) systems
are similarly affected by the presence of fog and mist and suffer even lower
availabilities. However, it is speculated that heavy rain and fog/mist rarely occur
simultaneously. Therefore, frequency diverse systems, combining mm-wave and Free
Space Optical (FSO) systems, have the potential to provide very high availability with
reduced interference.
In this chapter we present the analysis of the data collected on the 500 m range at
Chilbolton, during the period April 1991 to September 1995. ( RA/RAL core project
“ Propagation above 50GHz” ) A previous document discussed the experiment and
initial analysis: “Report on the 500m Range Data”, Paulson and Gibbins, June 1991.
Five links were operated along the same 500 m path : four mm-wave links operated at
57, 97, 135 and 210 GHz; and a near optical link at 0.63 μm. Propagation measurements
were made by recording on computer the received signal strengths at 10 s intervals, with
periodic calibrations carried out by introducing known levels of attenuation into the
transmitters.
In this report we investigate the joint statistics of operation of the mm-wave link in
combination with the FSO link. These systems use frequency diversity to improve
availability. The system includes two links along the same path and carrying the same
information, at FSO and a mm wavelengths. As the two system fail under different,
and possibly mutually exclusive, meteorological conditions it is hoped that the dual
system would have very high availability. To examine this hypothesis, this report
examines the simultaneous fade measurements on the 632nm near optical link with each
of the mm wave links.
7.2 RESULTS
FSO and 57 GHz
The FSO link and 57 GHz link were both operational for 83.8% of the period 30/4/1992
to 4/9/1995. Figures 7.1 & 7.2 illustrate the attenuation statistics for the FSO link and
the 57 GHz link respectively. Y-axis indicates the attenuation threshold that was
exceeded for the percentage indicated by the x-axis values. Figure 7.3 shows the joint
statistics of the two links. The x-axis and y-axis values of Figure 7.3 indicate the
specific attenuation thresholds that were exceeded at the FSO and microwave link
respectively for the specified percentages. As the attenuation path was 500m long the
attenuation thresholds are approximately 0.5 times the specific attenuation thresholds.
For example the specific attenuation at 57 GHz link and FSO link was greater than
2dB/Km ( attenuation 1 dB) and 20 dB/Km (Attenuation 10 dB) for 0.001% of the
time. In other words when the attenuation at the 57 GHz link was above 1 dB the
attenuation at the FSO link was above 10 dB for the percentage of 0.001%. Whereas
when the attenuation at the 57 GHz link was above 5 dB the attenuation at the FSO link
171
Radio Systems at 60 GHz and Above
was above 7.5 dB for the percentage of 0.001%. For the different percentage of 0.010%
when the attenuation at 57 GHz was above 5 dB the attenuation at the FSO link was
above ~3.5 dB The S-shape cumulative distribution of optical link is due to very high
attenuation caused by fog. Optical links in general are not affected by rain ( as mmwaves links)
Figure 7.1: Attenuation statistics of the FSO link.
Figure 7.2: Attenuation statistics of the 57 GHz link
172
Radio Systems at 60 GHz and Above
Figure 7.3 : Joint Specific Attenuation statistics of FSO and 57 GHz links. The
contours are at probability exceedance 20, 10,5, 2, 1,0.1, 0.01 and 0.001%.
It is clear from figures 7.1 & 7.2 that the FSO link suffered much higher levels of
attenuation compared with the microwave link for the same percentages. For example
at 1% the attenuation threshold was ~1dB at 57 GHz whereas at the FSO link was ~35
dB. However the joint statistics (see Figure 7.3 ) indicate that deep fading at the two
frequencies did not occur simultaneously, verifying the potential significant increase in
availability possible with dual frequency configuration.
Similar conclusions derived from the analysis of 97, 135 and 210 GHz in combination
with FSO data.
FSO and 97 GHz
Figures 7.4 illustrates the attenuation statistics for the 97GHz whereas the joint specific
attenuation statistics in combination with the FSO are shown in Figure 7.5
173
Radio Systems at 60 GHz and Above
Figure 7.4: Attenuation statistics of the 97 GHz link
Figure 7.5: Joint Specific Attenuation statistics of FSO and 97 GHz links. The contours
are at probability exceedance 20, 10,5, 2, 1,0.1, 0.01 and 0.001%.
174
Radio Systems at 60 GHz and Above
FSO and 135 GHz
Figures 7.6 illustrates the attenuation statistics for the 97GHz whereas the joint specific
attenuation statistics in combination with the FSO are shown in Figure 7.7.
Figure 7.6: Attenuation statistics of the 135 GHz link
Figure 7.7: Joint Specific Attenuation statistics of FSO and 135 GHz links. The
contours are at probability exceedance 20, 10,5, 2, 1,0.1, 0.01 and 0.001%.
175
Radio Systems at 60 GHz and Above
FSO and 210 GHz
Figures 7.8 illustrates the attenuation statistics for the 97GHz whereas the joint specific
attenuation statistics in combination with the FSO are shown in Figure 7.9.
Figure 7.8: Attenuation statistics of the 210 GHz link
Figure 7.9: Joint Specific Attenuation statistics of FSO and 210 GHz links. The
contours are at probability exceedance 20, 10,5, 2, 1,0.1, 0.01 and 0.001%.
176
Radio Systems at 60 GHz and Above
7.3 CONCLUSIONS
Frequency bands above 60GHz suffer severely from rain. (Frequencies around 60GHz
suffer also from oxygen attenuation which in contrast with rain attenuation is always
present). Free Space Optical (FSO) systems are similarly affected by the presence of
fog and mist and suffer even lower availabilities. However the study of the joint
statistics between a microwave and optical link indicates that the deep fading at the two
frequencies did not occur simultaneously. This verifies the potential significant increase
in availability possible with the dual frequency configuration.
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Radio Systems at 60 GHz and Above
8
DEMONSTRATION AND
WORKING SYSTEMS
OPERATIONAL
TRIALS
OF
8.1 INTRODUCTION
The purpose of the Demonstration and Operational Trial was to verify the availability,
relaibility and performance of millimetre-wave radio equipment in routine production
and to consider its economic viability deployed in a commercial environment. For
comparative purposes, an FSO link equipment was also deployed in a dual
configuration on a parallel path.
OciusB2 hosted the trial at their site in Runcorn, Cheshire; the equipment was
commissioned to provide links between the main site and a business park at The Heath.
OciusB2 transmitted commercial traffic across both the 64GHz link and the FSO link.
Installation and deployment were completed by March 2005 and the operational
performance of the links was continuously monitored for system parameter errors and
failures through to November.
The trial also enabled a typical set of deployment costings to be generated, and dual
mm-wave/FSO link to be bench-marked against other technologies and deployment
options for short-range high data applications.
8.2 TRIAL SITE AND INSTALLATION
8.2.1 Location
The selected test site was at The Heath, Runcorn. This site is a managed high-tech
research and development campus, occupied by both new and established companies
with strong technology roots. Amongst the tenants are chemists and design companies
who utilise high speed data connectivity in their daily activities.
Ocius B2 Ltd provide data services across the site.
Location
178
Radio Systems at 60 GHz and Above
The Heath, Runcorn, a fully serviced
technology business park.
indicate
roof top terminals
Scale 500m/sq
179
Radio Systems at 60 GHz and Above
8.2.2 Installation
The equipment was installed exactly as if deployed on a commercial basis to provide
connectivity between two network routers operating at Gigabit and 100BaseT data rates
over a distance of approximately 450m in line-of-sight.
Installation was undertaken to mimic practices normally employed in a commercial
environment with care being taken to effect an installation without structural damage to
the fabric of the buildings.
Mounting detail of link equipment (60GHz radio only)
Connectivity to the equipment is by means of 4 fibre core cable, additional fibre being
installed at one end of the link to give access to the internal network. Local mains
supply was provided at each end. The cable termination is made within the container
box at the foot of the mounting pole at each end of the link.
Views along link path
180
Radio Systems at 60 GHz and Above
8.3 DEPLOYED EQUIPMENT AND INSTALLATION
8.3.1 System configuration
RAL/OFFCOM
60 GHz Trial
Network Drawing
C
C
A End Laser
Path
B End
laser
Equipment
Vlan 128K
Vlan 128K
B End Radio
A End Radio
Internet
1 Gig
100MB
100MB
1 Gig
OciusB 2 Network
OciusB 2 Network
The deployed configuration is as shown in the diagram above. Equipment is positioned
at two ends of the trial path – A and B. Both ends include laser-driven optical
equipment (FSO) with a specified maximum capacity of 100MBps, and millimeterwave radio equipment (MRE) with a specified maximum capacity of 1GBps. The FSO
and MRE equipments at ends A and B are all connected to the OciusB2 internal local
area network. The equipments are contolled and monitored by PCs at each end. Ttwo
cameras are positioned at end A, and connected to the monitor PC using a 128k VLAN.
One camera monitors the status of the equipment at end A, and the other monitors the
weather conditions along the link path.
Datasheets of the deployed equipments are reproduced overleaf.
181
Radio Systems at 60 GHz and Above
8.3.2 64GHz link equipment
The installation of the radio equipment was relatively simple, making use of internal
DC voltage indicator (relative RF power) to peak the alignment. There are no ‘user
serviceable’ controls on the radio, making it a ‘Plug and Play’ installation. Obvious
care needs to be taken to avoid erroneous alignment on a side lobe.
182
Radio Systems at 60 GHz and Above
8.3.3 Free space optical equipment
The FSO required considerable care in alignment even though this is undertaken using
an inbuilt alignment telescope. Again no user serviceable controls are required. It was
noted the FSO alignment was extremely sensitive, as would be expected. This raised an
issue of mounting mechanism rigidity that could impact severely on the ability of an
operator to deploy such equipment in a commercial environment where building fabric
concerns could arise.
183
Radio Systems at 60 GHz and Above
8.3.4 Network monitoring and alarms
As the installation was intended to mimic a commercial deployment, network
monitoring was established alongside the rest of the OciusB2 network connectivity to
generate alarms in the event of excessive latency and or network link failures.
The network monitoring system is configured to relay any such alarms onward via email to the RAL project engineer in addition to the duty engineer of OciusB2 Ltd.
In order to monitor the system, the links were added to the existing OciusB2 network
supervision system, where the following parameters are checked 5 times in every 10
seconds.
•
•
•
A warning alarm is raised if latency is experienced above 20mS and below 49mS
A critical alarm is raised if latency exceeds 50mS
A critical alarm is raised if the circuit fails.
184
Radio Systems at 60 GHz and Above
In the event of a failure alarm it was believed necessary to set in place a system to allow
examination of weather conditions (during daylight). To that end cctv cameras were set
up to enable real time visibility of both the equipment and the link path. This visual
inspection is date and time stamped so that it can be correlated against any physical
movement of the equipment and significant meteorological events that could affect the
links.
Screen grab of cctv Camera 1 (note FSO link mounted above 60GHz radio)
8.3.5 Weather monitoring
Examination of local weather conditions was limited to examining local statistics
retrospectively to any link alarms. Conditions at nearby Liverpool airport were used to
give indications of any correlation.
185
Radio Systems at 60 GHz and Above
Screen grab of example weather data
186
Radio Systems at 60 GHz and Above
8.4 SYSTEM PERFORMANCE
Continuous monitoring of the links was undertaken, allowing any alarms raised to be
examined. The units have been operational throughout the study period without any
loss of connectivity.
The system alarm parameters were set such that any link failure or packet loss would
raise an e-mail alarm to project managers both on- and off-site. It should be noted no
such alarms were generated except under test conditions when the links were
deliberately disrupted.
In the absence of a link failure or packet loss event, the link margins were assessed by
examining the link logs against an extreme weather event. On the 5th July 2005 a severe
storm crossed the area and radar plots were obtained of the event. The records of the
links were examined to consider any relationship or impact.
Storm radar plot for 5th July 2005
There was no apparent impact on the link performance. However, the system log did
show an increase in RTA, which is believed to be related directly to an unrelated and
coincidental network traffic increase, not to any deterioration in link performance as no
packet loses were recorded.
187
Radio Systems at 60 GHz and Above
Date
5th July
Status
60GHz
FSO
08.51
Alert
Packet Loss 0%
RTA 143.4dB
08.52
OK
08.58
Alert
Packet Loss 0%
RTA 165.7dB
08.59
OK
09.33
Alert
Packet Loss 0%
RTA 116.3dB
09.34
OK
10.23
Alert
Packet Loss 0%
RTA 124.4dB
10.24
OK
10.58
Alert
Packet Loss 0%
RTA 106.6dB
10.59
OK
11.28
Alert
Packet Loss 0%
RTA 113.4dB
11.29
OK
None
Monitoring log extract for 60 GHz and FSO
The commercial trial was designed to validate claims that reliable equipment was
commercially available. The trial was not intended to gather or review propagation data
– this task was included in sections 2 and 6 of the study. Propagation experiments are
deliberately conducted at the margins of link budgets, and data is recorded by accessing
signal levels within the test link equipment. In contrast, a demonstration of commercial
utility must be operated at a link budget margin which reduces the risk of outage to an
agreed low level, and equipment internal signal levels are not available.
Both links (FSO & 60GHz) operated without any failures during the study period and as
such offer a practical solution to the operational requirements of rapid deployment and
consistent performance.
Examination of the weather events experienced and forecast make it unlikely that any
link failures will be experienced without a reduction in link budgets. Alternative sites
for installation on the OciusB2 campus were explored but none with longer range were
available that would also allow commercial traffic to be passed over the link.
Furthermore, as the purpose of the demonstration was to carry commercial traffic,
deliberately reducing the link budget to trigger outages would be contrary to the
agreement with the traffic owners. The team intends to continue investigating the
60GHz solution beyond the period of the SES study. This will enable more potential
outage events to be logged. New equipment is now appearing in the market place and
this will also be assessed in the campus environment.
188
Radio Systems at 60 GHz and Above
8.5 ECONOMICS OF DEPLOYEMENT
The trial objectives included an examination of typical economics of deployment. The
installation of commercially available FSO and 64GHz microwave equipment in a
parallel configuration across the same path facilitated this. The chosen trial site was a
campus environment, where civil construction (including the laying of fibre) was a
possible alternative for connecting two routers on the network. The following cost
benefit comparison is between the combined FSO and 64GHz microwave equipment
costs and the fibre estimate.
Deployment decisions will be based on capacity requirement, capital cost and funding
mechanism, ease and speed of installation, and cost of ongoing maintenance.
Both the FSO and 64GHz systems operated satisfactorily: the 64GHz radio system
offered the easiest installation/deployment option.
Civil elements
Estimate surfaces
Bitmac Carriageway
Bitmac Footway
Footway boxes
Fibre
Install fibre
Sub Total
Common installation
Estimated elements
Internal cabling (capped)
Fibre termination 6core
Materials – Fibre
termination boxes
Fibre patch cords
Sub total
Units
Mtrs
50
500
8
520
520
150
£
75
55
230
15
15
£3,750
£27,500
£1,840
£7,800
£7,800
£48,690
12
25
10
£3,750
£120
2
4
25
15
£50
£60
3,980
Total
£52,670
Fibre cost estimate
In the above table, the sum of £3,980 represents within building connectivity costs
which are common to all three options (64GHz, FSO and fibre). The sum of £48,690
represents additional equipment and installation costs were a hard fibre route to be
constructed across the site.
As a guide, the 64GHz radio link cost and the FSO link cost were in the order of 30% of
the hard fibre link option.
It should of course be noted that this apparent significant saving should be assessed
against the system carrying capacity. The actual fibre material cost estimate of £7,800
189
Radio Systems at 60 GHz and Above
is significantly less than the current pricing of a radio link and it can theoretically carry
significant data beyond the capability of the radio link (1Gbit in the unit deployed).
8.6 TRIAL CONCLUSIONS AND FURTHER WORK
The links were successfully established using conventional installation practices within
an enterprise environment.
Both the 64GHz radio link and the FSO link have operated well with no reported link
failures over the installed distance of 450m.
Installation issues relate only to the rigidity of the FSO mounting: this could be a
significant concern in commercial deployment. The FSO had to be rested and mounted
with a very stable structure to ensure that the required line-of-sight path was achieved
and not disrupted by winds and/or vibrations.
An operational range of less than 1km for wide bandwidth connectivity using 60GHz
radio is practical. Installation is simple and rapid. Such links would appear to have
multiple applications in campus networking and ‘last mile’ environments.
Continuing monitoring of link security will be undertaken.
The purchase price of the radio hardware is not the cost driver. The market is starting
using this available kit.
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Radio Systems at 60 GHz and Above
9
CONCLUSIONS AND RECOMMENDATIONS
This reports contains the results of a work regarding Radio Systems at 60GHz and
above. This work includes theoretical studies and literature research regarding
applications, frequency sharing and regulation. A commercial millimetre-wave (at
60GHz) & FSO system was operated at Runcorn as a demonstrator of these systems. In
addition 4 years’ of existing data from four millimetre wave links and one FSO link has
been analysed to provide base-line operational data.
The following conclusions were drawn:
Examination of System Applications in the Bands 60-100 GHz & Identification of Key
Obstacles to Band Use
Millimetre wave communications systems at frequencies above 60 GHz have the
potential for very high capacities, especially as more than 10 GHz of bandwidth is
available in the current frequency allocations.
Spectrum that is not subject to the oxygen absorption effect exhibits behaviour which is
broadly similar to spectrum below 60GHz where, in the absence of precipitation fading,
the limit of propagation is the horizon.
Specific applications have been identified that require broad contiguous blocks of
spectrum e.g. radio transmission of gigabit ethernet services.
Millimetre wave communications applications need to operate over short paths (<
10km) and also need to take advantage of the high antenna gains and directivities,
which can be achieved with small antenna sizes (typically 10 < diameter < 30cms).
Two applications have been identified for further study. These are:
a. Wireless local area networks providing ~1Gbps capacity through
millimetre wave access points.
b. Very high capacity backhaul for either MESH or branch and tree
networks, operated in conjunction with very local wireless distribution
services at lower frequencies.
The exploitation of these bands requires the development of low-cost RF technology.
At the frequency range 60 – 100 GHz transmitter/receiver technology is reasonably
mature and mass-produced systems are commercially available ( see sections 3.2.2 and
3.3.2). For example transmitters with 10mW output power and receivers with 10dB
Noise Figure are available today to fulfill the radio link requirements for the
applications presented in section 2. .
Millimetre wave systems are not particularly suited to situations where long range is
required e.g. satellite or HAPS systems or where non-line of sight paths are experienced
(e.g. personal communications and home networks).
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Radio Systems at 60 GHz and Above
Millimetre wave systems, at ranges of more than 100m, provide a much better quality of
service, in adverse weather conditions (rain and fog), than free space optical (infra red)
systems.
Implications of Licensed and Licence-Exempt Use & A survey of International Activity
in Bands 60-100 GHz
Manufacturers are now launching useable product, especially near the oxygen peak at
60GHz. These products exploit USA-FCC rules and provide a range of typically 1km.
There is also some activity at higher frequencies with longer range but manufacturers
are waiting for orders before committing to production tooling.
European and other regulators are starting to respond, although the response is far from
uniform, e.g. between Europe, USA, and ROW. Within Europe some regulators are
establishing national regimes, but most have waited for the report of SE-19 (just
available as this report was in preparation). There is still a preponderance of formal
licensing, but some regulators will adopt a mix of unlicensed and lightly licensed
processes.
The bands 59-66 GHz : 71-76 GHz : 81-86 GHz should be opened on a lightly licensed
basis so as to satisfy growing demand.
‘Light licensing’ should be adopted. Traditional spectrum auctions have resulted in the
bands at 3,5GHz, 10,5GHz and 28GHz being privately owned but not deployed, and noone from manufacturing or operating industry has made a case for using the same failed
mechanisms in the new bands. Nevertheless, QoS requirements for the identified
applications require a degree of interference management. This could best be achieved
by following the new USA, low-cost, web-based registration scheme.
Due to the nature of the applications and the directivity of operational equipment in this
band, there should be no restriction on channel size. 10GB/s radio links would require
the full 5GHz spectrum.
In order to obtain the QoS required for the delivery of the identified applications, the
power levels given in tables A4.2 and A4.3 of the Draft ECC Document
ECC/REC/(05)07 ‘Radio Frequency Channel Arrangements for Fixed Service
System’ should be increased. Suitable limits for power at the antenna port for 1Gb in
both the 71-76GHz and 81-86GHz bands are 19dBm for FSK links, and 16QAM links.
There should be no modulation requirements or restrictions. It is believed that
BPSK/QPSK will be used in the majority of links due to the link length requirements
TPC should not be mandatory.
Ofcom should maintain an ongoing interest in the development of a Europe-wide
regulatory regime in the frequency bands between 60 and 100GHz that is sympathetic to
the needs of both operators and manufacturers; and that the development of both
regulations and market be continuously monitored throughout 2006.
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Radio Systems at 60 GHz and Above
Radio Channel Characterisation
Subject to the use of appropriate directional antennae line of sight paths operated with
low levels of multi-path components both in building and out of building.
Operation through glass was demonstrated with little degradation in multi-path
behaviour particularly for near normal incidence. Some smooth frequency selective
behaviour was observable across the frequency band measured.
Non line of sight propagation was observed to result in a wide spread of delay
components of near equal amplitude within a single corridor.
Non line of sight propagation around an obstacle was observed to occur at discreet
frequencies across the band measured only. At other frequencies transmission was
attenuated.
For outdoor links the strong reflection from adjacent structures must be considered
when selecting the antennae and the location of the terminal equipment.
The spectrum Efficiency of Frequency/Power Control & Dual Millimetre Wave/FSO
systems
Previous studies have investigated the spectrum efficiency benefits of implementing
ATPC in bands up to 38 GHz, primarily concentrating on fixed terrestrial links. In
higher frequency bands the situation is complicated by the 10GHz band around 60 GHz,
where the oxygen absorption band suppresses long distance transmissions, hence
enabling a reduction of the frequency reuse distance to as little as 1 km in some
situations.
The link layout scenario presented in this report is by necessity simplistic, dealing as it
does with only two links and a simplified rain model. Still the results suggest that ATPC
has the potential to improve spectrum efficiency in bands above 60GHz. As a worse
W/U is predicted in clear sky than in rain, designing a link to clear sky specifications
and compensating for rain fading dynamically on a dB by dB basis will minimise the
separation distance between the links.
Frequency bands above 60GHz suffer severely from rain. (Frequencies around 60GHz
suffer also from oxygen attenuation which in contrast with rain attenuation is always
present). Free Space Optical (FSO) systems are similarly affected by the presence of
fog and mist and suffer even lower availabilities. However the study of the joint
statistics between a microwave and optical link indicates that the deep fading at the two
frequencies did not occur simultaneously. This verifies the potential significant increase
in availability possible with the dual frequency configuration.
From measurements made at Chilbolton on the 500m range to achieve an availability of
99.99% on a FSO link, a fade margin of over 40 dB is required. For a radio link at 57
GHz, a fade margin of ~10 dB would be needed for the same availability. A combined
system using both a FSO link and a radio link at 57 GHz would require a 2 dB fade
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Radio Systems at 60 GHz and Above
margin on the radio link and a 10 dB fade margin for the FSO link, which is a
substantial reduction.
As with ATPC, reducing the transmit power of a radio link during clear sky conditions
will improve the rate of frequency reuse within a given geographical area. At this time,
effective and economic utilisation of the bands above 60 GHz is believed to be a higher
priority, as these frequencies are not commonly used.
Demonstration and Operational Trials of Working Systems
Both the 64GHz radio link and the FSO link have operated well with no reported link
failures over the installed distance of 450m.
An operational range of up to 1km for wide bandwidth connectivity using 60GHz radio
is practical. Installation is simple and rapid, and suitable equipment is commercially
available. Such links would appear to have multiple applications in campus networking
and ‘last mile’ environments.
194
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