Agilent Wireless Dictionary

Agilent Wireless Dictionary
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
ACELP
Algebraic Code Excited Linear
Predictive
An algebraic technique used to populate codebooks for
CELP speech coders. This technique results in more
efficient codebook search algorithms. [8]
ACIR
Adjacent Channel Interference Ratio
The ratio of wanted power to the interference power from
the adjacent channel(s). [2]
ACLR
Adjacent Channel Leakage Ratio
ACLR is a measure of transmitter performance for WCDMA. It is defined as the ratio of the transmitted power
to the power measured after a receiver filter in the adjacent
RF channel. This is what was formerly called Adjacent
Channel Power Ratio. ACLR is specified in the 3GPP WCDMA standard.
ACPR
Adjacent Channel Power Ratio
A measurement of the amount of interference, or power, in
the adjacent frequency channel. ACPR is usually defined
as the ratio of the average power in the adjacent frequency
channel (or offset) to the average power in the transmitted
frequency channel. It is a critical measurement for CDMA
transmitters and their components. It describes the amount
of distortion generated due to nonlinearities in RF
components. The ACPR measurement is not part of the
cdmaOne standard.
ACS
Adjacent Channel Selectivity
A measurement of a receiver's ability to process a desired
signal while rejecting a strong signal in an adjacent
frequency channel. ACS is defined as the ratio of the
receiver filter attenuation on the assigned channel
frequency to the receiver filter attenuation on the adjacent
channel frequency.
ACTS
Advanced Communications Technology One of the groups spearheading the development of 3G
and Services
technologies in Europe. ACTS succeeded RACE and is
focusing on wideband multiple access techniques.
adaptive equalizer
ADC
A channel equalizer whose parameters are updated
automatically and adaptively during the transmission of
data. These equalizers are commonly used in fading
channels to improve transmission performance. [4]
Analog-to-Digital Converter
Converter that uniquely represents all analog input values
within a specified total input range by a limited number of
digital output codes. [2]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
adjacent channel interference
Out of band power generated in adjacent channels by
transmitters operating in their assigned channel. The
amount of adjacent channel interference a receiver sees is a
function of transmitter and receiver filter characteristics
and the number of transmitters operating in the area.
ADPCM
Adaptive Differential Pulse Code
Modulation
An encoding technique using differential encoding and
variable sized quantizing steps. The variance of the step
sizes are based on estimates of past signal samples. [4]
ADSL
Asymmetrical Digital Line Subscriber
A method to increase transmission speed in a copper cable.
ADSL facilitates the division of capacity into a channel
with higher speed to the subscriber, typically for video
transmission, and a channel with significantly lower speed
in the other direction. [6]
AGC
Automatic Gain Control
System which holds the gain and, accordingly, the output
of a receiver substantially constant in spite of input- signal
amplitude fluctuations.
AGCH
Access Grant Channel
A downlink control channel used in GSM systems to
assign mobiles to a SDCCH for initial assignment.
AIN
Advanced Intelligent Network
A network of equipment, software and protocols used to
implement features on the network and support switching
and control functions. [1]
A-law companding
A type of non-linear (logarithmic) quantizing, companding
and encoding technique for speech signals based on the Αlaw. This type of compandor is used internationally and
has a similar response as the µ-law compandor, except it is
optimized to provide a more nearly constant signal-toquantizing noise ratio at the cost of some dynamic range.
[7]
aliasing
A type of signal distortion that occurs when sampling
frequency of a signal is less that the Nyquist rate.
ALOHA
A packet-based radio access protocol developed by the
University of Hawaii where every packet sent is
acknowledged. Lack of an acknowledgement is an
indication of a collision and results in a retransmission. [1]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
AM
Amplitude Modulation
CW modulation using amplitude variation in proportion to
the amplitude of the modulating signal; usually taken as
DSB-LC for commercial broadcast transmissions and
DSB-SC for multiplexed systems.
AMPS
Advanced Mobile Phone System
The original standard specification for analog systems.
Operates in the frequency range of 800 MHz, with a
bandwidth of 30kHz. Used primarily in North America,
Latin America, Australia and parts of Russia and Asia.
AMR
Advanced Multi Rate Codec
During 1999, ETSI standardized this new speech codec for
GSM. The codec adapts its bit-rate allocation between
speech and channel coding, thereby optimizing speech
quality in various radio channel conditions. For this reason,
3GPP (under which the next stage GSM speech quality
will be realized) has selected the AMR codec as an
essential speech codec for the next generation system.
AMR was jointly developed by Nokia, Ericsson and
Siemens.
analog system
A transmission method or way of sending voice, video and
data-using signals (such as electricity or sound waves) that
are continuously variable rather than discreet units as in
digital transmissions. The first networks for mobile
phones, built in the 1980s, were analog. Analog systems
include AMPS, NMT and ETACS.
angle diversity
A technique using multiple antenna beams to receive
multipath signals arriving at different angles. [4]
ANSI
American National Standards Institute
A non-profit organization in the US which pursues
standardization within the industrial sector. It is also a
member of ISO (International Standard Organization).
ANSI itself, however, does not establish standards. Instead,
it assists in reviewing proposals put forth by various
standardizing bodies in the US and accordingly assigns a
category code and number after approval.
antenna
The part of a radio transmission system designed to radiate
or receive electromagnetic waves. [7]
antenna beamwidth
More properly referred to as the half-power beamwidth,
this is the angle of an antenna pattern or beam over which
the relative power is at or above 50% of the peak power.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
antenna directivity
This is the relative gain of the main beam of an antenna
pattern to a reference antenna, usually an isotropic or
standard dipole.
antenna gain
See antenna directivity.
APC
Automatic Power Control
A technique of measuring the performance of a radio
channel and adjusting the power of the transmitter to a
level appropriate for link characteristics.
ARDIS
Advanced Radio Data Information
Systems
A radio system developed jointly by Motorola and IBM to
provide mobile data services. The system is now operated
solely by Motorola.
ARFCN
Absolute Radio Frequency Channel
Numbers
A channel numbering scheme used to identify specific RF
channels in a GSM radio system.
ARIB
Association of Radio Industries and
Businesses (Japan)
An incorporated body designated by the Ministry of Posts
and Communication of the Japanese government to pursue
effective radio utilization in the radio communication and
broadcast sector. With regard to standardization, ARIB is
currently primarily engaged in standardizing procedures
for IMT-2000 (next generation mobile communication
system) and digital TV broadcasting.
ARQ
Automatic Retransmission Request
A signal used in digital communications systems used to
signal the transmitting device to retransmit a block of data.
ASIC
Application-Specific Integrated Circuit An integrated circuit designed to perform a specific set of
functions, usually within a specific device.
asynchronous mode
A way to send transmissions by starting and stopping
transmissions with a code rather than sending
transmissions at specific time intervals as in synchronous
mode. Asynchronous communication devices do not have
to be synchronized with a clocking signal, which is
required with synchronous transmission. Also frequently
referred to as ATM or Asynchronous Transfer Mode. Can
also mean that there are different capacities for data
transfer in each direction, for example the old 90/200 baud
modems and the new ADSL. See also synchronous mode.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
ATM
Asynchronous Transfer Mode
A technology for broadband transmission of high-capacity
telecommunications signals. In addition to high-capacity
signal transmission, ATM provides considerable
flexibility, since the individual subscriber is able to adapt
the capacity of a switched connection to current
requirements.
attenuation
A decrease in signal magnitude between two points. These
points may be along a radio path, transmission line or other
device.
attenuator
A device specifically designed to decrease the magnitude
of a signal transmitted through it.
AUC
Authentication Center
A device, usually located in the HLR of a GSM system that
manages the authentication or encryption information
associated with individual subscribers.
autocorrelation
The complex inner product of a sequence with a shifted
version of its self. It is a measure of how closely a signal
matches a delayed version of itself shifted n units in time.
[4]
average power
An indication of the peak power averaged over time.
Usually applied to pulsed systems where the carrier power
is switched on and off.
AWGN
Additive White Gaussian Noise
Statistically random radio noise characterized by a wide
frequency range with regards to a signal in a
communications channel.
AXE
An open architecture, Ericsson's communications platform.
A system for computer-controlled digital exchanges that
constitute the nodes in large public telecommunications
networks. The basis for Ericsson's wireline and mobile
systems.
band
In wireless communication, band refers to a frequency or
contiguous range of frequencies. Currently, wireless
communication service providers use the 800 MHz, 900
MHz and1900 MHz bands for transmission in the United
States.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
band-pass filter
A radio wave filter having a specific range of frequencies it
is designed to pass, while rejecting frequencies outside the
pass-band.
bandwidth
The information-carrying capacity of a communications
channel. Usually expressed in Hertz (cycles per second) for
analog circuits and in bits per second (bps) for digital
circuits.
base station
The central radio transmitter/receiver that maintains
communications with a mobile radio telephone within a
given range.
baseband signal
A signal with frequency content centered around DC.
Typically the modulating signal for an RF carrier. [4]
BCCH
Broadcast Control Channel
A downlink point to multipoint logical channel in GSM
and cdma2000 systems used to send identification and
organization information about common control channels
and cell services. [1]
BCH
Broadcast Channels
A group of downlink point to multipoint logical channels
used by mobiles to synchronize to and receive information
necessary to access a cell in GSM, cdma2000, and WCDMA systems. [1]
BCH code
Bose-Chaudhuri-Hocquenghem Code
A family of powerful cyclic block forward error correction
codes used in the transmission of data. [6]
BER
Bit Error Rate
A ratio of the number of errors to data bits received on a
digital circuit. BER is usually expressed in exponential
form.
BERT
Bit Error Rate Tester
A device used to measure the bit error rate performance of
a data circuit.
bit interval
The amount of time, usually in milliseconds or
microseconds, a binary one is in the "on" position. [4]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
BLER
Block Error Rate
A ratio of the number of erroneous blocks to the total
number of blocks received on a digital circuit. Block error
rate (BLER) is used for W-CDMA performance
requirements tests (demodulation tests in multipath
conditions, etc). BLER is measured after channel deinterleaving and decoding by evaluating the Cyclic
Redundancy Check (CRC) on each transport block.
block code
A family of codes having a one-to-one mapping between ksymbol source words and n-symbol code words. [4]
blocking probability
The statistical probability that a telephone connection
cannot be established due to insufficient transmission
resources in the network. Usually expressed as a
percentage or decimal equivalent of calls blocked by
network congestion during the busy hour.
Bluetooth
A short range radio technology developed by Ericsson and
other companies that makes it possible to transmit signals
over short distances between telephones, computers and
other devices without having to interconnect them with
wires.
bps
Bits per Second
The units usually used to express data transmission speed;
the number of pieces of information transmitted per
second.
BPSK
Binary Phase Shift Keying
A type of phase modulation using 2 distinct carrier phases
to signal ones and zeros.
broadband
This term has a number of meanings. It was coined
originally to describe a channel having more bandwidth
than needed to carry a standard voice grade channel. It is
also the term for transmission equipment and media that
can support a wide range of electromagnetic frequencies.
Broadband frequencies can transmit more data and at a
higher speed than narrowband frequencies. In general,
paging services and traditional voice grade wireless phones
are considered narrow-band. High speed data and video
communications are usually considered broadband services
and employ broadband equipment.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
BS
Base Station
The equipment on the network side of a wireless
communications link. The base station contains the tower,
antennas and radio equipment needed to allow wireless
communications devices to connect with the network.
BSC
Base Station Controller
A device and software associated with a base station that
permits it to register mobile phones in the cell, assign
control and traffic channels, perform handoff and process
call setup and termination.
BSIC
Base Station Identity Code
A unique code contained in messages on the broadcast
channels of a cell or base station that uniquely identifies
the base station.
BSS
Base Station Subsystem
That portion of a GSM network that includes the base
station, base station controller and transcoders (if used). [1]
BT
Bandwidth Time Product
The result obtained by multiplying the system bandwidth
by the signal duration. As a general rule, the system
bandwidth must be approximately equal to the reciprocal
of the signal duration to produce an output signal of the
same general form as the input, i.e., BT≈1. [10]
BTA
Basic Trading Area
A geographic area over which a PCS operator is licensed to
provide service. BTAs are a group of counties in
metropolitan areas having common financial, commercial
and economic ties and were first used to license PCS
service in the middle '90s. BTAs are about the size of a
cellular MSA and cross state lines in some instances. BTAs
are used by the Rand-McNally corporation to summarize
economic data. BTAs are grouped into larger areas called
MTAs
BTS
Base Transceiver Station
Although specifications differ for each system, the BTS
effects radio communication with mobile stations (MS) via
its respective radio access system and transmits/receives
signals to/from connected radio network controllers (RNC)
located along transmission routes.
burst
A term, usually associated with a TDMA system,
describing a group of bits or other information transmitted
by the system. Also refers to the time the transmitter is on
and radiating. [4]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
C/I
carrier-to-interference ratio
See carrier-to-interference ratio. [1]
C/N
carrier-to-noise ratio
See carrier-to-noise ratio.
CAI
Common Air Interface
A set of open standards describing the physical and logical
characteristics of a link between a base station and mobile
station. These standards are used by infrastructure and
handset manufactures to design and build equipment that is
capable of interoperating with each others systems.
carrier recovery
A technique for extracting the RF carrier from a modulated
signal so that it can be reinserted and used to recover the
modulating signal.
carrier-to-interference ratio
The ratio of power in an RF carrier to the interference
power in the channel.
carrier-to-noise ratio
The ratio of power in an RF carrier to the noise power in
the channel.
CBCH
Cell Broadcast Channel
A downlink point to multipoint logical channel in a GSM
system used to broadcast user information from a service
center to mobile stations listening in a given cell area. [1]
CCDF
Complementary Cumulative
Distribution Function
A method used to characterize the peak power statistics of
a digitally modulated signal. The CCDF curve can be used
to determine design parameters for CDMA systems (such
as the amount of back-off to run in a power amplifier). [9]
CCH
Control Channel
A general term used to describe the channels that transmit
signaling and control information between the network and
the mobile stations. [1]
CDF
Cumulative Distribution Function
The cumulative probability that a parameter will be less
than a given value X.
CDG
CDMA Development Group
A technical organization dedicated to developing the
CDMA technology and promoting its use world-wide.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
CDMA
Code Division Multiple Access
One of several digital wireless transmission methods in
which signals are encoded using a specific pseudo-random
sequence, or code, to define a communication channel. A
receiver, knowing the code, can use it to decode the
received signal in the presence of other signals in the
channel. This is one of several "spread spectrum"
techniques, which allows multiple users to share the same
radio frequency spectrum by assigning each active user an
unique code. CDMA offers improved spectral efficiency
over analog transmission in that it allows for greater
frequency reuse. Other characteristics of CDMA systems
reduce dropped calls, increase battery life and offer more
secure transmission. See also IS-95.
cdma2000
The name identifying the TIA standard
(IS-2000) for third generation
technology that is an evolutionary
outgrowth of cdmaOne.
A radio transmission technology for the evolution of
narrowband cdmaOne/IS-95 to 3rd-generation adding up
multiple carriers. See also W-CDMA for single
carrier/direct spread technology.
cdmaOne
Brand name describing a complete wireless system
incorporating the IS-95 CDMA air interface.
CDP
Code Domain Power
A measurement of the power contained in each Walsh
coded channel in CDMA signals. The CDP measurement is
beneficial in troubleshooting CDMA transmitter designs.
CDPD
Cellular Digital Packet Data
An open wireless transmission standard allowing two-way
19.2-Kbps packet data transmission over existing cellular
telephone channels (AMPS with CDPD capability.) In
essence, CDPD technology uses idle network capacity
caused by pauses in phone conversations and gaps between
calls placed, etc. to transmit data.
CDVCC
Coded Digital Verification Color Code A unique 12 bit code word used to identify the base station.
It performs the same function as the SAT in an analog
system it that it is added at the base station to the downlink
or forward channel. The mobile then detects and returns
the code. The CDVCC is used to determine channel
continuity, and only one CDVCC is usually assigned to a
base station or sector. [1]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
cell
The geographic area encompassing the signal range from
one base station (a site containing a radio
transmitter/receiver and network communication
equipment). Wireless transmission networks are comprised
of many hexagonal, overlapping cell sites to efficiently use
radio spectrum for wireless transmissions. Also, the basis
for the term "cellular phone."
cell splitting
The process of splitting a cell into several smaller cells.
This us usually done to make more voice channels
available to accommodate traffic growth in the area
covered by the original cell.
cellular
In wireless communications, cellular refers most basically
to the structure of the wireless transmission networks
which are comprised of cells or transmission sites. Cellular
is also the name of the wireless telephone system originally
developed by Bell Laboratories that used low-powered
analog radio equipment to transmit within cells. The terms
"cellular phone" or "cell phone" are used interchangeably
to refer to wireless phones. Within the wireless industry,
cellular is also used to refer to non-PCS products and
services.
cellular handoff
In cellular communications, a telephone call is switched by
computers from one transmitter to the next, without
disconnecting the signal, as a vehicle moves from cell to
cell. The mobile remains on a specific channel until signal
strength diminishes, then, is automatically told to go to
another channel and pick up the transferred transmissions
there.
cellular mobile telephone system
System where each geographic area is covered by a base
station. This area is known as a cell. Each telephone in the
cell communicates with the base station. If the phone
moves to another cell, the call is automatically transferred
to the base station in the new cell.
CELP
Code-Book Excited Linear Predictive
A powerful low-rate coding technique where a short
excitation frame, typically 5ms, is modeled by a Gaussian
vector chosen from a large stochastic codebook. The vector
is chosen such that the error between the original and
synthesized speech is minimized. [2]
CEPT
Committee of European Posts &
Telephones
A European regulatory body responsible for coordinating
telecommunications within Europe.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
CGSA
Cellular Geographic Service Area
A general term used to describe the physical area over
which a cellular carrier is licensed to provide service. See
also MSA, RSA, MTA, BTA, EA and REAG.
channel
A general term used to describe a communications path
between two systems. They may be either physical or
logical depending on the application. An RF channel is a
physical channel, whereas control and traffic channels
within the RF channel would be considered logical
channels.
channel coding
The application of forward error correction codes to an RF
channel to improve performance and throughput.
channel equalization
The process of reducing amplitude, frequency and phase
distortion in a radio channel with the intent of improving
transmission performance. [7]
CIF
Common Intermediate Format
A video image format using 352 horizontal pixels and 288
vertical lines. The format is adopted in multimedia
communication standards.
circuit switched
A switched circuit is only maintained while the sender and
recipient are communicating, as opposed to a dedicated
circuit which is held open regardless of whether data is
being sent or not.
clock recovery
The process of extracting the timing signals from a
digitally modulated carrier wave. The recovered clock
signal is then used to decode and further process the data.
co-channel interference
Unwanted interference within a radio channel from another
transmitter using the same channel at a different location.
Co-channel interference is very common in a frequency
reuse system and must be carefully controlled to prevent
problems. [1]
codebook
An ordered collection of all possible values that can be
assigned to a scalar or a vector variable. Each vector is
called a codeword. [4]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
CODEC
Coder/Decoder
An amalgam of the terms "Coder" and "Decoder". It
generally signifies the encoding device/module which
carries out highly efficient conversion processing from the
basic digital signal to a compressed signal during
digitalization of voice and picture signals. Encoding
specifications for the voice CODEC and image CODEC
are stipulated by the G-series and H-series ITU-T
recommendations, respectively. In the case of mobile
communication, encoding specifications are established by
the concerned standardizing bodies.
coding gain
The effective gain, usually in dB, that coding provides over
an uncoded signal. Coding gain is usually measured as the
dB difference in C/N ratios between a coded and uncoded
signal producing the same BER.
coherent detection
Also referred to as coherent demodulation, this is a
technique of phase locking to the carrier wave to improve
detection. Knowledge of the carrier phase improves
demodulator performance.
companding
Compressing and Expanding
A technique for reducing the dynamic range of a baseband
signal. This reduces the number of quantizing steps needed
and reduces noise in the process. Most digital systems
include nonlinear quantizing to achieve this effect. [4]
concatenated coding
The use of two codes, an inner and outer code, to further
improve transmission performance. Using this technique, a
data stream is encoded with the outer code and then the
coded data is further encoded with the outer code. This
technique is particularly effective in bursty environments.
The use of concatenated codes is most common in space
communications and usually involves a convolutional inner
code and Reed-Solomon outer code. [4]
constellation
A graphical representation of signal states for a digital
system. [2]
control channel
A channel, usually logical, used to send administrative and
supervisory signals between a base station and a mobile
station.
convolutional code
A type of forward error correction code using a shift
register containing a number of stages to shift the input bits
one at a time to produce a coded output. [1]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
COST-231
ETSI propagation model for 2 GHz applications.
coverage area
The geographical reach of a mobile communications
network or system.
coverage hole
An area within the radio coverage footprint of a wireless
system in which the RF signal level is below the design
threshold. Coverage holes are usually caused by physical
obstructions such as buildings, foliage, hills, tunnels and
indoor parking garages.
CPM
Continuous Phase Modulation
A phase modulation technique employing smooth
transitions between signal states. This reduces sidelobe
spectral energy and improves co-channel performance. [2]
CRC
Cyclic Redundancy Code
The use of the syndrome of a cyclic block code to detect
errors. [4]
cross correlation
The complex inner product of a first sequence with a
shifted version of a second sequence. Sequences are
considered to have good cross correlation properties when
there is very little correlation between the sequences as
they are shifted against each other. [4]
cross talk
The ability for unwanted information from one channel to
"spill over" into an adjacent channel. [4]
CT-2
CT-3
CTIA
Cordless Telephone 2
A second generation cordless telephone system that
allowed users to roam away from their home base stations
and receive service in public places. Away from the home
base station, the service was one way outbound from the
phone to a telepoint within range. [1]
See DECT.
Cellular Telecom Industry Association The membership-based association, located in Washington,
D.C., represents the interests of the wireless
telecommunications industry.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
CW
Continuous Wave
The term commonly gives to an unmodulated RF carrier.
These are a subclass of linear block codes with an
algebraic structure that enables encoding to be
implemented with a linear shift register and decoding to be
implemented without a lookup table. [4]
cyclic codes
DAC
Digital to Analog Converter
A device that takes a digital representation of a signal and
transforms it into a facsimile of its original form.
D-AMPS
Digital-Advanced Mobile Phone System Earlier designation of American standard for digital mobile
telephony used primarily in North America, Latin America,
Australia and parts of Russia and Asia. Also known as
(North American) TDMA. See also TDMA and IS-136.
dB
deciBel
A technique for expressing voltage, power, gain, loss or
frequency in logarithmic form against a reference. Typical
references include volts, watts or Hz. DeciBels are
calculated using the expression: dB = 10*log(x/y).
dBc
deciBels referenced to the carrier
A technique for expressing a power measurement in
logarithmic form using the carrier power as a reference.
dBd
deciBels referenced to a dipole antenna A technique for expressing a power gain measurement in
logarithmic form using a standard dipole antenna as a
reference.
dBi
deciBels referenced to an isotropic
antenna
A technique for expressing a power gain measurement in
logarithmic form using a theoretical isotropic antenna as a
reference.
dBm
deciBels referenced to a milliWatt
A technique for expressing a power measurement in
logarithmic form using 1 mW as a reference.
DCA
Dynamic Channel Allocation
An automatic process for assigning traffic channels in a
frequency reuse wireless system. The base station
continuously monitors the interference in all idle channels
and makes an assignment using an algorithm that
determines the channel that will produce the least amount
of additional interference.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
DCCH
Dedicated Control Channel
A dedicated channel used to carry signalling information in
active GSM and cdma2000 traffic channels.
DCS-1800
Digital Communications System - 1800 A delta spec to the GSM specification dealing with the
aspects of operating in the 1800 MHz band with an
increased number of RF channels. This spec also included
features for pedestrian operation of small portable devices.
[1]
dead spot
DECT
An area within the coverage area of a wireless network in
which there is no coverage or transmission falls off. Dead
spots are often caused by electronic interference or
physical barriers such as hills, tunnels and indoor parking
garages. See also coverage area.
Digital European Cordless
Telecommunications
A common standard for cordless personal telephony
originally established by ETSI, a European standardization
body. Standard based on a micro-cellular radio system that
provides low-power cordless access between subscriber
and base station up to a few hundred meters. Also known
as DCT-900 and CT-3. [1]
delay spread
A type of distortion due to multipath resulting in the
spreading out or "smearing" of the received signal. It
occurs when identical signals arrive via different paths and
have different time delays. [1]
demodulation
Process of recovering the original modulating signal from a
modulated carrier. The original modulating signal is
usually the information being transmitted, typically voice
or data.
differential detection
An encoding and detection technique that uses phase
changes in the carrier to signal binary "ones" and "zeros".
The signal is sampled every T seconds, and a phase change
of 180 degrees could be set to be a "zero" and no phase
change would then be a "one". [9]
diffraction
A propagation phenomenon that allows radio waves to
propagate beyond obstructions via secondary waves
created by the obstruction. Classic types of diffractions are
smooth earth and knife-edge. [4]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
digital
Describes when information - speech, for example - is
encoded before transmission using a binary code - discrete,
non-continuous values. Digital networks are rapidly
replacing analog ones as they offer improved sound
quality, secure transmission and can handle data as well as
voice. Digital networks include mobile systems GSM 900,
GSM 1800, GSM 1900, D-AMPS and the cordless DECT
system.
digital signature
An electronic signature. A technology used to guarantee
the reliability of information during electronic transactions.
Digital signaturing is enabled through the application of
open key encryption technology, and comprises electronic
data verifying the identity of the user. A digital signature is
created by coding data using an encryption key. Since only
the user him/herself is in possession of the corresponding
encryption key, the digital signature is essentially
unforgeable. The digital signature is subsequently attached
to data transmitted to another party to guarantee that the
individual sending the message really is who he or she
claims to be. [2]
dispersive channel
A radio channel that not only introduces AWGN, but also
the effects of multipath and frequency selective fading.
distributed antenna system
A type of antenna system that is distributed or remotely
located away from the transmitter. Such an antenna or
series of antennas can be connected via coaxial cable,
leaky feeder or optical fiber link. [4]
diversity
A technique to reduce the effects of fading by using
multiple spatially separated antennas to take independent
samples of the same signal at the same time. The theory is
that the fading in these signals is uncorrelated and that the
probability of all samples being below a threshold at a
given instant is low. [5]
DL
Downlink
See downlink. [1]
Doppler Shift
The magnitude of the change in the observed frequency of
a wave due to the relative velocity of a transmitter with
respect to a receiver.
downlink
The transmission path from the base station down to the
mobile station. [7]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
DPM
Digital Phase Modulation
A form of CPM in which the shaped symbol pulses are
directly applied to the phase modulator. This technique
provides the advantages of CPM techniques and is easily
implemented in VLSI. It is also easier to demodulate than
other types of CPM.
DQPSK
Differential Quadrature Phase Shift
Keying
QPSK modulation using differential encoding of the digital
information stream.
DS
Direct Sequence
A process of spectrum spreading where the digital
information stream is multiplied, using an exclusive OR
technique, by a high speed pseudorandom code (spreading
sequence) to generate a spread spectrum signal.
DSSS
Direct Sequence Spread Spectrum
A type of spread spectrum modulation using a direct
sequence technique to achieve spreading.
DTX
Discontinuous Transmission
A feature in mobile systems where transmitters mute when
there is no information to send, such as during periods of
silence. This feature prolongs battery life in portable
phones and reduces interference in wireless systems.
dual band
A term describing mobile phones that work on networks
operating on different frequency bands. This is useful for
mobile phone users who move between areas covered by
different networks. For example GSM 900, GSM 1800.
such as the 800 MHz digital band and the 1900 MHz
digital PCS band.
dual mode
An industry term referring to a wireless device that can
operate on either an analog or digital transmission network.
However, multiple digital transmission systems exist, so
dual-mode phone users must ensure that their dual-mode
phone will operate on the digital transmission system used
by their selected service provider.
duplex/full duplex
Simultaneous two-way transmission, such as experienced
in a phone conversation. In contrast, many speakerphones
are half-duplex and will transmit in only one direction
phone conversation. In contrast, many speakerphones are
half-duplex and will transmit in only one direction - from
the loudest noise - at a time.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
DUT
Device Under Test
An acronym used to describe some type of electrical
apparatus connected to test instrumentation. The apparatus
can range from a single component to a complex
subsystem such as a mobile phone, base station or MSC.
EA
Economic Area
A geographic area over which a WCS operator is licensed
to provide service. EAs are a group of counties in
metropolitan areas having common financial, commercial
and economic ties and were first used to license WCS
service in the late '90s. EAs are about the size of a cellular
MSA and cross state lines in some instances. EAs are used
by the FCC to define areas of economic interest and are
grouped into larger areas called REAGs.
Eb/N0
Bit Energy-to-Noise Density
The ratio of bit energy to noise density. This value is used
to specify the lower limit of operation in most digital
communications systems and is also used to measure radio
channel performance.
EDGE
Enhanced Data for Global Evolution
A technology that gives GSMA and TDMA similar
capacity to handle services for the third generation of
mobile telephony. EDGE was developed to enable the
transmission of large amounts of data at a high speed, 384
kilobits per second. (It increases available time slots and
data rates over existing wireless networks.)
EFR
Enhanced Full Rate
The second generation full rate speech codec used in GSM
systems. This codec replaced the original RPE-LTP codec
used in GSM systems. This codec employs ACELP
technology. [2]
EHF
Extremely High Frequency
The RF spectrum between 30 GHz and 300 GHz.
EIA
Electronic Industry Association
A trade association and standards setting organization in
the USA.
EIR
Equipment Identity Register
A database used by GSM and other second generation
wireless systems used to identify the customer devices
permitted to access the network. A device is usually placed
in the EIR once its operation has been certified for the
infrastructure in a laboratory or validation facility. [1]
EIRP
Effective Isotropic Radiated Power
A measure of the power in the main beam of an antenna
relative to an isotropic radiator. [1]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
encryption
A cryptographic technique utilizing a digital key to
scramble and hence "lock" data in such a manner that it
cannot be descrambled and decoded without the key.
EPOC
An operating system that turns voice-oriented handsets into
Mediaphones and Wireless Information Devices. EPOC
places a lighter load on the processor compared to present
PDA operating systems and thus has the capacity to
enhance the multimedia capacity of mobile phones. EPOC
is being developed by Symbian, a joint company of Psion,
Nokia, Ericsson, Motorola and Matsushita (Panasonic). It
constitutes an open platform optimized for mobile phone
use.
equalization
Measures taken to reduce the distortion effects in a radio
channel. [4]
ERMES
European Radio Message System
A pan-European wide area paging network working in
Europe, the Middle East and Asia.
error correction
The process of correcting errors in data transmitted over a
radio channel using forward error correction (FEC)
techniques.
error distribution
A description of how errors in a communications channel
are distributed. Typical distributions are Gaussian
(random) and Raleigh (bursty). [2]
error probability
A computation of the likelihood of an error involving the
Probability Density Function (PDF). [2]
error vector
The error vector is the vector difference between a
reference signal and a measured signal and is a complex
quantity containing a magnitude and phase component. [5]
ESMR
Enhanced Specialized Mobile Radio
The application of second generation wireless technology
to the Specialized Mobile Radio Services.
ESN
Electronic Serial Number
A unique electronic identifier given to a mobile terminal.
This number is used in verifying the identity of the mobile
terminal. [1]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
ETACS
Extended Total Access Communications The analog mobile phone network developed in the UK
System
and available in Europe and Asia.
E-TDMA
Enhanced TDMA
ETSI
European Telecommunications Standard The European standardization body for
Institute
telecommunications.
EVM
Error Vector Magnitude
A TDMA technique using Digital Speech Interpolation
(DSI) and half rate coding to allow six calls to be carried in
three time slots. The system does this by taking advantage
of the 40% speech activity factor. [1]
EVM is a modulation quality metric widely used in digital
RF communications systems. It is the root-mean-square
(rms) value of the error vector over time at the instants of
symbol clock transitions. Used properly, EVM and related
measurements can pinpoint exactly the type of
degradations present in a signal and can even help identify
their sources. [5]
extranet
The extension of a company's intranet out onto the Internet,
e.g. to allow selected customers, suppliers and mobile
workers to access the company's private data and
applications via the World Wide Web. Generally an
extranet implies real-time access through a firewall of
some kind.
eye diagram
A superposition of segments of a received PAM signal
displayed on an oscilloscope or similar instrument. The eye
diagram is used to assess impairments in the radio channel.
[4]
FACCH
fading
Fast Associated Control Channel
The channel derived by preempting information in a traffic
channel. It is used to send handoff and similar messages.
[1]
The variation in signal strength from it normal value.
Fading is normally negative and can be either fast or slow.
It is normally characterized by the distribution of fades,
Gaussian, Rician, or Rayleigh. [6]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
fast fading
The short term component associated with multipath
propagation. It is influenced by the speed of the mobile
terminal and the transmission bandwidth of the signal. [4]
fast packet switching
An emerging, packet-orientated, digital technology that
differs from traditional packet switching in a number of
ways. The most obvious is that it transmits all data in a
single packet format whether the information is video,
voice or data. Fast packet switching uses short, fixed
length packets (cells) and - via hardware switching - is
capable of speeds between 100,000 and 1,000,000
packets/second.
FAW
Frame Alignment Word
A unique digital word used by codecs to allow them to resynchronize to the framing structure in the event of errors.
[2]
FCC
Federal Communications Commission
Regulatory body governing communications technologies
in the US. established by the Communications Act of 1934,
as amended, and regulates interstate communications
(wire, radio, telephone, telegraph and telecommunications)
originating in the United States.
FCCH
Frequency Correction Channel
A logical channel in GSM systems used to transmit a
frequency correction data burst of all "zeros". The resulting
frequency shift seen by the mobile is then used for
frequency correction. [1]
FDD
Frequency Division Duplex
Radio technology using a paired spectrum. Used in cellular
communication systems such as GSM.
FDMA
Frequency Division Multiple Access
Method of allowing multiple users to share the radio
frequency spectrum by assigning each active user an
individual frequency channel. In this practice, users are
dynamically allocated a group of frequencies so that the
apparent availability is greater than the number of
channels.
FEC
Forward Error Correction
An encoding technique that allows a limited number of
errors in digital stream to be corrected based on knowledge
of the encoding scheme used.
FER
Frame Erasure/Error Rate
A measure of the number of frames of data that contained
errors and could not be processed. FER is usually
expressed as a percentage or exponent.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
FH
Frequency Hopping
A periodic changing of frequency or frequency set
associated with transmission. A sequence of modulated
pulses having a pseudorandom selection of carrier
frequencies. [1]
FHMA
Frequency Hopped Multiple Access
A set of frequency hopping communicators operating as a
system to provide communications services. All
communicators traditionally use the same set of carrier
frequencies and coordinate their hopping sequences to
minimize interference in the network. [1]
FHSS
Frequency Hopped Spread Spectrum
A spectrum spreading technique using an RF carrier
hopped across a large number of RF channels using a
random or pseudorandom code to determine the sequence
of channels used.
FIR
Finite Impulse Response
A technique used to characterize electrical circuits and
networks in the time domain. [3]
flat fading
FM
A type of fading in a communications channel that
attenuates or fades all frequencies in the channel the same
amount. [5]
Frequency Modulation
A form of angle modulation in which the instantaneous
frequency of a sine-wave carrier is caused to depart from
the carrier frequency by an amount proportional to the
instantaneous value of the modulating wave. [7]
forward link
See downlink. [4]
framing
A technique used in digital communications systems for
organizing the transmitted data into regular patterns so that
the various logical channels in the data stream can be
detected and processed.
frequency diversity
The simultaneous use of multiple frequencies to transmit of
information. This is a technique used to overcome the
effects of multipath fading, since the wavelength for
different frequencies result in different and uncorrelated
fading characteristics. [5]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
frequency reuse
A technique of reusing frequencies and channels within a
communications system to improve capacity and spectral
efficiency. Frequency reuse generally utilizes regular reuse
patterns.
frequency selective fading
A type of signal fading occurring over a small group of
frequencies caused by a strong multipath component at
those frequencies.
FSK
A form of modulation using multiple carrier frequencies to
carry the digital information. The most common is the two
frequency FSK system using the two frequencies to carry
the binary ones and zeros.
Frequency Shift Keying
full rate
The term commonly applied to voice codecs in a
communications system. Most frame formats are designed
to accommodate full and half-rate channels, with the
intention of implementing half-rate coding as the
technology permits to double the capacity of the system.
The full-rate codec uses all of the time-slots available.
Gaussian channel
An RF communications channel having the properties of
wide-band uniform noise spectral density resulting in a
random distribution of errors in the channel. [2]
GGSN
Gateway GPRS Support Node
A gateway from a cellular network to an IP network.
GHz
Gigahertz
A frequency measurement which equals one billion hertz.
GMSK
Gaussian Minimum Shift Keying
A modulation technique involving Gaussian filtering of the
input data prior to its application to the phase modulator.
This results in a narrow occupied spectrum and better
adjacent channel interference performance. [2]
GOS
Grade of Service
A measure of the success a subscriber is expected to have
in accessing a network to complete a call. The grade of
service is usually expressed as percentage of calls
attempted by the subscriber during the busy-hour that are
blocked due to insufficient network resources.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
GPRS
General Packet Radio Service
A packet-linked technology that enables high-speed (115
kilobit per second) wireless Internet and other data
communications over a GSM network. It is considered an
efficient use of limited bandwidth and is particularly suited
for sending and receiving small bursts of data.
GPS
Global Positioning System
A worldwide radio-navigation system that was developed
by the US. Department of Defense. In addition to military
purposes it is widely used in marine and terrestrial
navigation (for example car navigation systems).
GSM
Global System for Mobile
Communication
Originally developed as a pan-European standard for
digital mobile telephony, GSM has become the world's
most widely used mobile system. It is used on the 900
MHz and 1800 MHz frequencies in Europe, Asia and
Australia, and the MHz 1900 frequency in North America
and Latin America.
GSM 1800
A digital network working on a
frequency of 1800 MHz.
It is used in Europe, Asia-Pacific and Australia. Also
known as DCS 1800 or PCN.
GSM 1900
A digital network working on a
frequency of 1900 MHz.
It is used in the US and Canada and is scheduled for parts
of Latin America and Africa. Also known as PCS 1900.
GSM 900
GSM 900, or just GSM, is the world's most widely used
digital network and now operating in over 100 countries
around the world, particularly in Europe and Asia Pacific.
guard band
A set of frequencies or band-width used to prevent adjacent
systems from interfering with each other. Guard bands are
typically used between different types of systems at the
edges of the frequency allocations.
HAAT
half rate
Height Above Average Terrain
A measure of an antenna's height above average terrain.
This value is used by the FCC in determining compliance
with height limitations and transmitting powers for high
sites.
The term commonly applied to voice codecs in a
communications system. Most frame formats are designed
to accommodate full and half-rate channels, with the
intention of implementing half-rate coding as the
technology permits to double system capacity. The halfrate codec uses only half of the time-slots in the frame. [1]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
Hamming code
A well known simple class of block codes capable of
detecting up to two errors and correcting one. Although not
particularly powerful, they are one of the "perfect" codes in
that its standard array has all of the error patterns that can
exist for single errors. [3]
hand-off
The process of transferring a call in progress from the
current base station to another without interruption as the
user moves out of range of the current base station.
hand-over
The passing of a call signal from one base station to the
next as the user moves out of range or the network
software re-routes the call.
hard hand-off
A term used in CDMA systems to describe a hand-off
involving a frequency change. The hard hand-off is a break
before make hand-off just like in other wireless systems
and must be used where the current and hand-off candidate
base stations do not use the same RF channel. See also soft
hand-off. [5]
Hata model
Common name used for the Okamura-Hata model used to
predict signal strength levels in land-mobile systems.
HLR
Home Location Register
The functional unit responsible for managing mobile
subscribers. Two types of information reside in the HLR:
subscriber information and part of the mobile information
that allow incoming calls to be routed to the mobile
subscriber. The HLR stores the IMSI, MS ISDN number,
VLR address, and subscriber data on supplementary
services. [1]
HPSK
Hybrid Phase Shift Keying
The spreading technique used in the reverse link of 3G
systems to reduce the peak-to-average ratio of the signal by
reducing zero crossings and 0 degree phase transitions.
Also known as Orthogonal Complex Quadrature Phase
Shift Keying (OCQPSK). For more information see
Agilent application note "HPSK Spreading for 3G".
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
HSCSD
High Speed Circuit Switched Data
A circuit-linked technology for higher transmission speeds
- up to 57 kilobits per second - primarily in GSM systems.
Hz
Hertz
A radio frequency measurement (one hertz = one cycle per
second).
I
In-Phase
For PSK modulation, the reference phase channel. See also
Q.
IF
Intermediate Frequency
The operating frequency in superheterodyne receivers
where amplification, filtering and level control prior to
demodulation is accomplished.
IMAP4
Internet Messaging Access Protocol
A remote mailbox access protocol. It enables efficient
operation such as downloading only essential data by first
acquisitioning the e-mail header prior to actual e-mail
download. This feature makes the protocol well suited to
remote environments.
IMEI
International Mobile Station Equipment An identification number assigned to GSM mobile stations
that uniquely identifies each one. It is a 15 digit serial
Identity
number that contains a type approval code, final assembly
code and serial number. [1]
i-mode
Internet Mode
A wireless service launched in Japan in spring 1999 by
NTT DoCoMo. The service is accessed by a wireless
packet network (PDC-P) and the contents are described in
a subset of the HTML language.
IMSI
International Mobile Station Identity
A unique 15 digit number assigned to a mobile station at
the time of service subscription. It contains a mobile
country code, a mobile network code, mobile subscriber
identification number, and a national mobile subscriber
identity. [1]
IMT-2000
International Mobile
Telecommunication 2000
A term used by the International Telecommunication
Union, a United Nations agency, to describe the third
generation mobile telephony due to be ready in 2000. Can
also be applied to mobile telephone standards that meet a
number of requirements in terms of transmission speed and
other factors.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
IMTS
Improved Mobile Telephone Service
A further development of the Mobile Telephone Service
(MTS) introduced by the Bell System. This version of
mobile service add channels and features, such as
automatic dialing, and was the forerunner to the AMPS
system. [1]
IN
Intelligent Network
Often referred to as the Advanced Intelligent Network, this
is a network of equipment, software and protocols used to
implement features on the network and support switching
and control functions.
interleaving
The process of spreading a block of data over a wider time
frame by placing data bits from other data blocks in
between the original data bits in the block. Interleaving is
frequently done in digital system to spread the data so that
bits from the same block are not contiguous and bit errors
are randomized to the point FEC is more effective.
Systems using this technique are more likely to withstand
Rayleigh and other bursty fading and interference
phenomenon. [2]
Internet capability
Functionality in a wireless network enabling access to the
Internet for web page viewing and e-mail purposes.
IP
Internet Protocol
A set of instructions defining how information is handled
as it travels between systems across the Internet.
IPR
Intellectual Property Rights
Also known as patents, these are the rights of an inventor
or assignee to develop and commercialize an invention and
license it, usually for a fee, to other manufacturers.
IPv6
Internet Protocol version 6.
The latest IP version. Address exhaustion is prevented by
means of a long address field, thereby enabling further
Internet expansion. In addition, security and mobility are
built into the protocol. Currently utilized IP addresses are
almost all IPv4, and with the present rate of Internet
growth this type of address will be exhausted by 2010.
IPv6 on the other hand enables 10 to the 29th power more
available addresses than the previous IPv4.
IS-136
EIA Interim Standard 136 - NADC with The North American digital mobile telephony standard
Digital Control Channels
based on TDMA technology. It is the version of the
TDMA specification resulting in a fully digital 2nd
generation system and is backward compatible with analog
AMPS. See also TDMA and D-AMPS.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
IS-2000
EIA Interim Standard 2000 (see
cdma2000)
A standard for current CDMA systems providing a
migration path to 3G services.
IS-41
Inter-network connection protocol for
connecting systems based on both
analog and digital US standards.
Inter-network connection protocol for connecting systems
based on both analog and digital US standards.
IS-54
EIA Interim Standard for U.S. Digital
Cellular
Original TDMA digital standard. Implemented in 1992.
This standard was the first to permit the use digital
channels in AMPS systems. It used digital traffic channels
but retained the use of analog control channels. This
standard was replaced by the IS-136 digital standard in
1996.
IS-95
EIA Interim Standard 95 (see cdmaOne) The original digital mobile telephony standard based on
CDMA technology. See also CDMA.
ISDN
Integrated Services Digital Network.
A technology offering switched and fixed high speed
transmission of voice, data and video through the existing
telephone infrastructure. The service is based on 1 or more
64 kbps digital channels and does not use traditional
modems.
ISI
Inter-Symbol Interference
An interference effect where energy from prior symbols in
a bit stream is present in later symbols. ISI is normally
caused by filtering of the data streams.
ITU
International Telecommunications
Union
A United Nations agency that deals with
telecommunications issues.
IWF
Interworking Function
A technique for interfacing data between a wireless system
and the telephone network. It usually involves the use of
modems or data terminal adapters to convert the data
transmitted over the air interface and mobile network to a
format that can be recognized and carried by the public
telecommunications network.
kHz
kiloHertz
A radio frequency measurement (one kilohertz = one
thousand cycles per second).
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
LAI
Location Area Identity
Information carried in the SIM of GSM handsets that
identify the subscriber's home area. This is used for billing
and sub-net operation purposes.
LAN
Local Area Network
A small data network covering a limited area, such as
within a building or group of buildings.
Lee's model
A slope-intercept propagation prediction model developed
at Bell Laboratories and popularized by William Lee. The
model assumes an initial condition at a short distance from
a base station and uses that as one end of a slope intercept
model to predict path loss between a base station and a
mobile unit.
link
The radio connection between a transmitter and a receiver.
link budget
A calculation involving the gain and loss factors associated
with the antennas, transmitters, transmission lines and
propagation environment used to determine the maximum
distance at which a transmitter and receiver can
successfully operate.
LMDS
Local Multipoint Distribution System
The name given to point-to-multipoint systems operating at
29 GHz and carrying high speed digital traffic. These
systems are usually laid out like cellular systems and are
currently being used by entrepreneurs to provide
competitive services to the local telephone companies. [4]
LNA
Low Noise Amplifier
A receive preamplifier having very low internal noise
characteristics placed very near the antenna of a receiver to
capture the C/N before it can be further degraded by noise
in the receiving system. [1]
location registration
One of several computer databases used to maintain
location and other information on mobile subscribers. See
HLR and VLR.
logical channel
A communications channel derived from a physical
channel. A physical channel, i.e. RF channel, typically
carries a data stream that contains several logical channels.
These usually include multiple control and traffic channels.
[5]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
LOS
loss of signal
A condition where the received signal drops below
threshold due to a terrain obstruction or other phenomenon
increasing the link budget loss beyond design parameters.
[2]
LOS
line of sight
A description of an unobstructed radio path or link between
the transmitting and receiving antennas of a
communications system. [5]
LPA
linear power amplifier
The final amplification stage in a multicarrier transmitter
that has been designed and optimized to produce a linear
response. By operating in the linear mode, the amplifier
reduces the non-linear effects that produce intermodulation
products and side-lobe spectra that cause adjacent channel
interference.
LPC
Linear Predictive Coding
A speech encoding scheme that uses periodic pulses to
excite a filter, similar to the way human voice is produced.
The code is predictive in that it uses knowledge of past
data (represented as vectors) to predict future values in a
feed forward manner. [1]
LSB
Least Significant Bit
In a binary coding scheme, the bit having the least
numerical value. Analogous to the units position in a
decimal number.
lu
Standardized interface between a Radio Network
Controller Network and Packet Subsystem (e.g. RNC3GSGSN).
lub
Interface between a Base Station and Radio Network
Controller.
lur
Open RNC-RNC interface.
MAC
macro cell
Medium Access Control
The protocols that arbitrate access between all nodes of a
wireless LAN. [4]
A large cell in a wireless system capable of covering a
large physical area. Macrocells are used in rural areas and
other areas where subscriber or traffic densities are low.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
MAHO
Mobile Assisted Handoff
A handoff technique involving feedback from the mobile
station as part of the handoff process. The feedback is
usually in the form of signal level and quality
measurements on the downlink and signal level
measurements from neighbor cells.
MAP
Mobile Application Part
A protocol using the lower level layers of the SS7 protocol
stack (TCAP, SCCP and MTP) for communication
between the various registers and other MSCs. [11]
The receiver filter with impulse response equal to the timereversed, complex conjugate impulse response of the
combined transmitter filter-channel impulse response. [4]
matched filter
MC-CDMA
Multi-Carrier Code Division Multiple
Access
Typically, this means the combination of three IS-95
carriers to form one wideband carrier. It is an evolution of
IS-95 for third generation systems. Also called cdma2000.
The current nomenclature is temporary, with a formal
name for this technology to be determined under 3GPP2.
Mcps
Mega Chips per Second
A measure of the number of bits (chips) per second in the
spreading sequence of direct sequence spreading code.
MHz
Megahertz
A unit of frequency equal to one million hertz or cycles per
second. Wireless communications occur in the 800 MHz,
900 MHz and 1900 MHz bands.
micro cell
MIN
µ-law companding
A base station with a very small coverage area designed to
provide service in areas having a very high density of
mobile subscribers. Microcells are traditionally used in
convention centers, airports and similar areas.
Mobile Identification Number
A unique identification number given to a mobile unit. In
most cases, this number is the telephone number of the
handset. In the case of analog cellular, the MIN is used to
route the call. In most second generation system, the
system assigns temporary numbers to the handset to route
calls as a security precaution. See also TMSI. [1]
A type of non-linear (logarithmic) quantizing, companding
and encoding technique for speech signals based on the µlaw. This type of companding uses a µ factor of 255 and is
optimized to provide a good signal-to-quantizing noise
ratio over a wide dynamic range.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
MMM
Mobile Media Mode
The WWW:MMM logo is a marketing innovation
comprising a unifying industry-wide marketing symbol
representing leading edge web-based products and
services.
MMS
Multimedia Messaging Service
MMS is a new standard that is being defined for use in
advanced wireless terminals. The service concept is
derived from Short Message Service and allows for nonreal-time transmission of various kinds of multimedia
contents like images, audio, video clips, etc. As a further
evolution of the current text mail, for example, electronic
postcards, audio/video clips, etc. can be sent.
mobile phone network
A network of cells. Each cell is served by a radio base
station from where calls are forwarded to and received
from your mobile phone by wireless radio signals.
modulation
The process of coding and decoding information for
transmission. For example, a voice conversation is coded
into binary bits (digital information), transmitted and then
decoded at the receiving end. [1]
MOS
Mean Opinion Score
A statistical rating and scoring technique used to rate the
performance of telephone connections by users. [2]
MPE
multi-pulse excited
A multi-pulse process for determining the position and
amplitude of sample pulses in a speech codec.
MPEG
Moving Picture Experts Group
The group that has defined the standards for compressed
video transmission. Can also refer to the file format itself.
MPEG4
Moving Picture Experts Group
Compression Standard Version 4.
MPEG4 is a technology for compressing voice, video and
related control data and is one of the MPEG (Moving
Picture Experts Group) international standards. It is
currently a focus of attention due to the fact that it enables
high speed and stable video transmission even in
heretofore difficult environments such as mobile
communication. Incorporation of this leading edge
technology will imbue 3G terminals with a rich multimedia
capability.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
MS
Mobile Station
The term used to describe the customer terminal in a
wireless network.
MSA
Metropolitan Statistical Area
A geographic area over which a cellular operator is
licensed to provide service. MSAs are groups of counties
in metropolitan areas having common financial,
commercial and economic ties and were first used to
license cellular service in the early '80s. MSAs cross state
lines in some instances. MSAs were first used by the Dept.
of Commerce to collect economic data.
MSB
Most Significant Bit
In a binary coding scheme, the bit having the greatest
numerical value. Analogous to the left-most numeric
position in a decimal number.
MSC
Mobile Switching Center
The location providing the mobile switching function in a
second generation network wireless network. The MSC
switches all calls between the mobile and the PSTN and
other mobiles.
MSK
Minimum Shift Keying
A modulation technique using sinusoidal shaped input data
pulses to drive the phase modulator. This results in a linear
phase change over conventional QPSK, resulting in lower
side lobes and less adjacent channel interference
performance. [1]
MTA
Major Trading Area
A geographic area over which a PCS operator is licensed to
provide service. MTAs are a group of BTAs having
common financial, commercial and economic ties and were
first used to license PCS service in the middle '90s. MTAs
can be many times larger a cellular MSA and can cross
multiple state lines in some instances. MTAs are used by
the Rand-McNally corporation to summarize economic
data. MTAs are one of the largest licensing areas used by
the FCC.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
MTSO
Mobile Telephone Switching Office
The location providing the mobile switching function in a
first generation wireless network. The MTSO switched all
calls between the mobile and the PSTN and other mobiles.
multipath
A propagation phenomenon characterized by the arrival of
multiple versions of the same signal from different
locations shifted in time due to having taken different
transmission paths of varying lengths. [2]
multiple access
The process of allowing multiple radio links or users to
address the same radio channel on a coordinated basis.
Typical multiple access technologies include FDMA,
TDMA, CDMA, and FHMA.
NADC
North American Digital Cellular
See IS-136. [1]
NAM
Number Assignment Module
The programmable module in an AMPS analog phone used
to contain the MIN, ESN, home system ID and other
information.
N-AMPS
Narrowband Advanced Mobile Phone
System
Combines the AMPS transmission standard with digital
signaling information to effectively triple the capacity of
AMPS while adding basic messaging functionality.
nested codes
A type of concatenated block code where the layers (inner
and outer) are amalgamated in such a way that burst errors
not able to be corrected by the inner code are sufficiently
spread over enough blocks as to be corrected by the outer
layer. [2]
NMC
Network Management Center
An operations center used to manage network resources
such as the MSC, location registers and base stations.
NMT
Nordic Mobile Telephony
The common Nordic standard for analog mobile telephony
as established by the telecommunications administrations
in Sweden, Norway, Finland and Denmark in the early
1980s. NMT systems have also been installed in some
European countries, including parts of Russia, and in the
Middle East and Asia. NMT is operated in 450 MHz and
900 MHz bands.
NMT-450
Nordic Mobile Telephony - 450
An early cellular system developed and operated in
northern Europe utilizing the 450 MHz band.
Wireless Dictionary
Acronym/Term
Acronym Definition
noise figure
Explanation
A figure of merit for receivers and preamplifiers
representing the amount of excess noise added to the signal
by the amplifier or receiving system itself. The lower the
noise figure, the less excess noise is added to the signal.
NRZ
Non Return to Zero
A type of data stream where successive data pulses "ones"
are continuous over several clock cycles without returning
to the "zero" state between successive "ones". [1]
NSS
Network Switching Subsystem
That portion of a GSM network that manages the
connections and communications within the network. The
BSS and OSS complete the major components of the
network. [2]
Nyquist filter
An ideal low pass filter with a cutoff frequency equal to the
sampling rate. This technique is used to convert PAM
pulses to an analog signal in D/A converters. [3]
Nyquist rate
The minimum sampling rate proposed by Nyquist for
converting a band limited waveform to digital pulses. The
rate must be at least twice the highest frequency of interest
in the waveform being sampled.
OAM&P
Operations, Administration,
Maintenance & Provisioning Center
OCQPSK
Orthogonal Complex Quadrature Phase Also known as HPSK. See HPSK. [2]
Shift Keying
OFDM
Orthogonal Frequency Division
Multiplex
Okamura model
OMC
An operations center used to operate, administer, maintain
and provision the network.
A modulation technique that transmits blocks of symbols
in parallel by employing a large number of orthogonal subcarriers. The data is divided into blocks and sent in parallel
on separate sub-carriers. By doing this, the symbol period
can be increased and the effects of delay spread are
reduced. [4]
A propagation prediction model for land-mobile
communications developed by Yoshi Okamuar et al. in the
late '60s. [1]
Operations & Maintenance Center
A location used to operate and maintain a wireless
network.
Wireless Dictionary
Acronym/Term
Acronym Definition
operator
Explanation
Company that operates a telephone network, for example
AT&T, Vodaphone and BT. [1]
OQPSK
Offset Quadrature Phase Shift Keying
A type of QPSK modulation that offsets the bit streams on
the I and Q channels by a half bit. This reduces amplitude
fluctuations and helps improve spectral efficiency.
ORFS
Output Radio Frequency Spectrum
A measurement for GSM signals that tests for interference
in the adjacent frequency channels (ARFCNs) and results
from two effects: modulation within the bursts and the
power that ramps up and down, or switching transients.
ORFS is a critical GSM transmitter measurement. [5]
OSI
Open System Interconnect
A reference model that describes a layered structure for
modeling the interconnection and exchange of information
between users in a communications system. The 7 layers
are: the physical layer, the link layer, the network layer, the
transport layer, the session layer, the presentation layer and
the application layer. [8]
OVSF
Orthogonal Variable Spreading
Function
A set of spreading codes derived from tree structured set of
orthogonal codes and are used to channelize the IMT2000/ULTRA system. [2]
PA
Power Amplifier
A device for taking a low or intermediate-level signal and
significantly boosting its power level. A power amplifier is
usually the final stage of amplification in a transmitter.
PABX
Private Automatic Branch Exchange
A customer premise telephone switching system capable of
interfacing to a telephone central office with trunk groups
and routing calls based on a 3 or 4 digit telephone
extension number.
packet
A piece of data transmitted over a packet-switching
network such as the Internet. A packet includes not just
data but also address information about its origination and
destination.
packet radio
A radio system that operates by sending data in packets.
Wireless Dictionary
Acronym/Term
Acronym Definition
packet switching
Explanation
A method of switching data in a network where individual
packets of a set size and format are accepted by the
network and delivered to their destinations. The sequence
of the packets is maintained and the destination established
by the exchange of control information (also contained in
the packets) between the sending terminal and the network
before the transmission starts. The network is open to all
users, all the time, with packets from the various nodes
being interleaved throughout the network. The packets can
be sent in any order, as the control information sent at the
beginning of the transmission ensures they are interpreted
in the correct order at the receiving end. Because each
packet carries its own control instructions, it can use any
route to reach its destination. [1]
PACS
Personal Access Communications
System
A low mobility low power wireless system designed for
residential use. [1]
PAD
Packet Assembler/Disassembler
The part of a packet transmission system that segments the
transmit data into packets and returns the receive data to
longer messages. [5]
pad
See attenuator.
paging
Single direction radio service for alerting subscribers and
delivering messages. [1]
PAM
pulse amplitude modulation
A technique for encoding the samples of an analog
waveform as part of the PCM process. Also used to display
the amplitude of QAM signals in an eye diagram.
partial response signalling
A signalling technique in which a controlled amount of
intersymbol interference is introduced at the transmitter to
shape the transmitted spectrum. [4]
path loss
The amount of loss introduced by the propagation
environment between a transmitter and receiver.
PBX
Private Branch Exchange
An exchange system used in companies and organizations
to handle internal and external calls.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
PCH
Paging Channel
A logical channel in GSM, cdma2000, and W-CDMA
systems used to send messages to mobile station. Used
primarily to notify the mobile that it has an incoming call.
[1]
PCIA
Personal Communications Industry
Association
A leading international trade association representing the
personal communications services (PCS) industry. Its
primary objective is to advance regulatory policies,
legislation, and technical standards in this industry.
PCM
Pulse Code Modulation
The most predominant type of digital modulation in use
today. PCM performs an analog to digital conversion of the
speech waveform through a sampling process and encodes
and transmits the samples in a serial bit stream as 8-bit
digital words. [4]
PCN
Personal Communications Network
A standard for digital mobile phone transmissions
operating at a frequency of 1800 MHz (also referred to as
GSM 1800). It is used in Europe and Asia Pacific.
PCS
Personal Communications Services
Generally, a marketing term used to describe a wide
variety of two-way digital wireless service offerings in
North America operating at 1900 MHz. PCS services
include next generation wireless phone and communication
services, wireless local loop, inexpensive walk-around
communications service with lightweight, low-powered
handsets, in-building cordless voice services for business,
in-building wireless LAN service for business, enhanced
paging service as well as wireless services integrated with
wired networks. A Personal Communications System
refers to the hardware and software that provide
communications services.
PCS
Personal Communications System
The infrastructure used to provide personal
communications services.
PDA
Personal Data Appliance/Assistant
Also known as Personal Digital Appliance.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
PDC
Personal or Pacific Digital Cellular
A Japanese standard for digital mobile telephony in the 800
MHz and 1500 MHz bands. To avoid the previous problem
of lack of compatibility between the differing types of
earlier analog mobile phones in Japan (i.e. NTT type and
US developed TACS type), digital mobile phones have
been standardized under PDC. In the case of the PDC
standard, primarily six channel TDMA (Time Division
Multiple Access) technology is applied. PDC, however, is
a standard unique to Japan which renders such phone units
incompatible with devices which adopt the more
worldwide prevalent GSM standard. Nevertheless,
digitalization under the standard enables ever smaller and
lighter mobile phones which in turn has spurred market
expansion. As a result, over 93% of all mobile phones in
Japan are now digital. [5]
PDF
Probability Density Function
The probability that X lies between two values, x1 and x2.
[10]
peak power
The maximum instantaneous power radiated by a pulsed or
bursted transmitter. It is the power radiated while the
transmitter is keyed or operated. [2]
phase jitter
The amount of uncertainty introduced in digital
demodulation caused by imperfections in the clock
recovery timing. [2]
PHP
Personal Handy Phone
The mobile hand-set used with the Japanese Personal
Handy Phone system.
PHS
Personal Handy Phone System
A digitalized evolution of the earlier analog cordless phone
concept which enables outdoor use as well. PHS
incorporates a unique Japanese standard which melds the
advantages of the European DECT and CT2. The system
operates in the 1.9 GHz band. [2]
physical channel
The actual radio channel that carries the various logical and
traffic channels in a wireless system.
pico cell
Very small cell in a mobile network for boosting capacity
within buildings.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
pilot code
This is a logical channel in a CDMA system characterized
by an unmodulated direct sequence spread-spectrum signal
continuously monitored by each base station. It allows the
mobile stations to acquire the timing of the forward
channel, serves as a phase reference for demodulation, and
allows the mobile to search out the best (strongest) base
stations for acquisition and hand-off. [4]
pilot pollution
A type of co-channel interference in CDMA systems
caused when the pilot code from a distant cell or base
station is powerful enough to create an interference
problem.
PIN
Personal Identification Number
A code used for all GSM-based phones to establish
authorization for access to certain functions or information.
The PIN code is delivered together with your subscription.
PLL
Phase Locked Loop
PLL is a major component in the frequency synthesizer
scheme. This device provides a wide, flexible range of
internal frequency dividers which allow the designer the
ability to create a synthesizer to match design
requirements.
PLMN
Public Land-Mobile Network
A European term used to describe the GSM system.
PMR
Private Mobile Radio
Generally for use within a defined user group such as the
emergency services or by the employees of a mining
project.
PN
Pseudo-Noise
Historically, the Ministry of Post, Telecommunications and
Telegraph. Now a term to describe the incumbent,
dominant operator in a country, many of which are being
or have been privatized.
PNCQPSK
Pseudo-Noise Complex Quadrature
Phase Shift Keying
The spreading technique that uses basic complex
scrambling and PN signals for Is and Qs. For more
information see Agilent application note "HPSK Spreading
for 3G".
POCSAG
Post Office Code Special Advisory
Group
An international group that develops and sets standards for
the paging industry. [4]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
polarization diversity
A diversity technique where antennas of different
polarizations, I.e. horizontal and vertical, are used to
provide diversity reception. The antennas take advantage
of the multipath propagation characteristics to receive
separate uncorrelated signals. [1]
power control
A technique for managing the transmit power in base
stations and mobiles to a minimum level needed for proper
performance. Downlink power control applies to base
stations and uplink power control to mobiles. Power
control is used in nearly all wireless systems to manage
interference, and in the case of mobiles, to extend battery
life.
power spectral density
Power normalized to 1 Hz. Knowing the power spectral
density and system bandwidth, the total power can be
calculated.
PQA
Palm Query Applications
An Internet clipping application developed from HTML
code and run on Palm PDAs. The application is designed
to streamline the flow to the PDA to minimize the number
of kilobytes sent and ultimately paid for. [2]
PRBS
Pseudo-Random Binary Sequence
A digital signal having framing information and using
pseudo-noise in the individual traffic channels. Commonly
used to performance test PCM systems. [1]
PRMA
Packet Reservation Multiple Access
PRMA is a packet-based TDMA concept where the users
contend for the time slots. In situations where the system is
not near capacity, a user can reserve a time slot for future
use. [2]
processing gain
The amount of gain, in dB, provided by the spreading code
in a CDMA system, usually the ratio of the spreading rate
to the information rate. [4]
propagation
The process an electromagnetic wave undergoes as it is
radiated from the antenna and spreads out across the
physical terrain. See also propagation channel. [2]
propagation channel
The physical medium electromagnetic wave propagation
between the transmit and receive antennas, and includes
everything that influences the propagation between the two
antennas. [2]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
PSD
Power Spectral Density
See power spectral density.
PSK
Phase Shift Keying
A broad classification of modulation techniques where the
information to be transmitted is contained in the phase of
the carrier wave.
PSTN
Public Switched Telephone Network
Standard domestic and commercial phone service.
PTT
Historically, the Ministry of Post, Telecommunications and
Telegraph. Now a term to describe the incumbent,
dominant operator in a country, many of which are being
or have been privatized. [2]
punctured code
A technique used in convolutional decoders that allows a
limited number of coded bits to be deleted to greatly
simplify processing in the codec. This is extremely useful
with long codes. [2]
Q
Quadrature-Phase
The quadrature phase channel in a phase shift keyed
system having more that 2 phase states.
QAM
Quadrature Amplitude Modulation
A type of modulation where the signalling information is
carried in the phase and amplitude of the modulated carrier
wave. [4]
QCIF
Quarter CIF (1/4 CIF). A video image
format which employs 176 horizontal
pixels and 144 vertical lines.
Although resolution is courser than CIF, QCIF consumes
less memory while still achieving an acceptable level of
clarity on small displays such as those incorporated in
mobile phones.
QoS
quality of service
A measure of the quality of the signal transmitted over the
RF channel. In some systems, the QoS measurement is
used to dynamically adjust operational parameters such as
transmitter power levels and coding rates.
QPSK
Quadrature Phase Shift Keying
A type of phase modulation using 2 pairs of distinct carrier
phases, in quadrature, to signal ones and zeros. [4]
Wireless Dictionary
Acronym/Term
Acronym Definition
quantizing
Explanation
The process of assigning values to waveform samples by
comparing the samples to discrete steps. [2]
RACE
Research in Advanced Communications An ETSI research project that has subsequently been
Equipment
replaced by ACTS. [1]
RACH
Random Access Channel
The channel used by mobiles in GSM and W-CDMA
systems to attempt to gain access to the system when first
attaching to it.
radio link
The equipment and transmission path (propagation
channel) used to carry on communications. It includes the
transmitting system, the propagation channel and receiving
system. [1]
radio port
The T1P1 PCS architecture model equivalent to the BTS.
radio propagation
The science associated with the description of
electromagnetic waves at radio frequencies as they radiate
from a transmitting antenna. [1]
rake receiver
A radio receiver having multiple "fingers" and utilizing
off-sets of a common spreading code to receive and
combine several multipath (time delayed) signals, in effect
using "time diversity" to overcome deep fades. [2]
RAN
random access
Radio Access Network
The ground-based infrastructure required for delivery of
third-generation (3G) wireless communications services,
including high-speed mobile access to the Internet. The
RAN must be able to manage a wide range of tasks for
each 3G user, including access, roaming, transparent
connection to the public switched telephone network and
the Internet, and Quality of Service (QoS) management for
data and Web connections. [2]
A technique for radio access to a network where an access
message is not coordinated or administered by the network
and can collide with other attempts by others to access the
network over the same channel.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
Rayleigh channel
A communications channel having a fading envelope in the
form of the Rayleigh Probability Density Function. [2]
Rayleigh fading
A type of signal fading caused by independent multipath
signals having a Rayleigh PDF.
RC
Radio Configuration
RC defines the physical channel configuration of
cdma2000 (IS-2000) signals. Each RC specifies a set of
data rates based on either 9.6 or 14.4 kbps. RC1 is the
backwards-compatible mode of cdmaOne for 9.6 kbps
voice traffic. It includes 9.6, 4.8, 2.4, 1.2 kbps data rates
and operates at Spread Rate 1 (SR1). RC3 is a cdma2000
specific configuration based on 9.6 kbps that also supports
4.8, 2.7, and 1.5 kbps for voice, while supporting data at
19.2, 38.4, 76.8, and 153.6 kbps. RC3 also operates at SR1.
For more information see Agilent application note
"Performing cdma2000 Measurements Today".
REAG
Region
A geographic area over which a WCS operator is licensed
to provide service. REAGs are a group of economic areas
(EAs) and were first used to license WCS service in the
late '90s. REAGs are very large, with 6 REAGs covering
the entire continental United States.
receive diversity
The process of providing two independent receiving
systems and spatially separated antennas to overcome
fading effects on the radio signal.
receiver
Arrangement of active components such as the LNA, mixer
and IF amplifier together with passive components such as
the image filter and IF filter. Taken together they perform
the task of recovering the modulation from a known RF
signal while rejecting unwanted signals. The portion of the
communication system that includes a detector and signal
processing electronics to convert electrical signals (electric
waves) to audio or data signals. It provides reception and,
if necessary, demodulation of electronic signals. [2]
Reed Solomon code
A particular implementation of the BCH block (cyclic)
coder capable of correcting double errors. [4]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
reflection
A process that occurs when a propagating electromagnetic
wave impinges upon a obstruction whose dimensions are
very large when compared to the wavelength. Reflections
from the surface of the earth, and from buildings or walls
produce reflected waves which may interfere,
constructively of destructively at the receiver. [1]
registration
This is the process by which a mobile station informs the
immediate service provider of its presence in the network
and its desire to receive service.
Repeater
Receives radio signals from the base station. They are then
amplified and re-transmitted to areas where radio shadow
occurs. Repeaters also work in the opposite direction, i.e.
receiving radio signals from mobile telephones, then
amplifying and re-transmitting them to the base station.
reuse factor
Also known as frequency reuse factor, is the number of
distinct frequency sets used per cluster of cells.
reverse link
See uplink. [2]
RF
radio frequency
Electromagnetic waves in the frequency range of 30 kHz to
300 GHz. [2]
Rician channel
A transmission channel that may have a line-of-sight
component and several scattered of multipath components.
This fading characteristic exhibits a Rician PDF. [2]
Rician fading
A type of signal fading having a characteristic similar to
the Rician PDF. [1]
RNC
Roaming
Radio Network Controller under the
UMTS system.
A complex network element of the RAN that connects to
and co-ordinates as many as 150 base stations in WCDMA systems. It is involved in managing activities such
as hand-over of active calls between base stations.
Within your home network, this means that your mobile
phone automatically sets up communication procedures
with different radio base stations when on the move.
International roaming means that you can use networks
other than your own when traveling abroad.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
Router
A data switch that handles connections between different
networks. A router identifies the addresses on data passing
through the switch, determines which route the
transmission should take and collects data in so-called
packets which are then sent to their destinations.
Routing
The forwarding of data packets in packet-switched
networks, to the intended address.
RPE-LTP
Regular Pulse Excited-Long Term
Prediction
A type of speech coding using regularly spaced pulses in
an excitation frame and a long term predictor to model the
fine structure (pitch).
RSA
Rural Service Area
A geographic area over which a cellular operator is
licensed to provide service. RSAs are a group of rural
counties having common financial, commercial and
economic ties and were used to license cellular service
Rural areas in the latter '80s. RSAs cross state lines in
some instances and were developed during a public rule
making process at the FCC in 1987 and 1988..
RSSI
Received Signal Strength Indication
An indication of the average signal strength at the input of
a receiver produced by measurement circuitry in the
receiver. Such a measurement does not normally include
antenna gain or transmission system losses. [2]
A type of video coding used in H.261 and H.263 codecs.
[4]
run length coding
S/I
signal-to-interference ratio
See signal-to-interference ratio.
S/N
signal-to-noise ratio
See signal-to-noise ratio.
SACCH
Slow Associated Control Channel
A low-speed control channel associated with a traffic
channel and used to transmit supervision and control
messages between the mobile and the network. [8]
sampling
The first process performed in the conversion of analog
waveforms to a digital format. It converts a continuoustime signal into a discrete-time signal or sequence of
numbers.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
SAT
Set-up Audio Tone
An audio tone in the 6 kHz range added to the downlink or
forward channel in analog cellular systems. The mobile
detects and returns the tone. The SAT tone is used to
determine channel continuity, and only one SAT tone is
usually assigned to a base station or sector.
Satellite phone
A type of wireless mobile telecommunications system
using satellites as base stations. Such systems have the
ability of providing service to the oceans and other remote
areas of the globe. [4]
scattering
A phenomenon that occurs when the medium through
which a radio wave travels consists of objects with
dimensions small compared to the wavelength and diffuses
the wave as it propagates through it. [1]
SCCH
Signaling Control Channel
A logical channel used in the PDC system to convey
signalling information between the mobile and the
network. [1]
SCH
Synchronization Channel
A logical channel used by mobile stations to achieve time
synchronization with the network. Used in GSM,
cdma2000, and W-CDMA systems. [1]
SDCCH
Slow Dedicated Control Channel
A low-speed bi-directional point-to-point control channel
used to transmit service request, subscriber authentication,
ciphering initiation, equipment validation and traffic
channel assignment messages between the mobile and the
network. [1]
SDH
Synchronous Digital Hierarchy
An international standard for synchronous optical
transmission. This standard allows the world-wide
connection of digital networks.
SDMA
Space Division Multiple Access
Also known as multiple beam frequency reuse, this
technique employs spot beam antennas to reuse frequencies
by pointing the antenna beams using the same frequency in
different directions.
sector
A physical coverage area associated with a base station
having its own antennas, radio ports and control channels.
The concept of sectors was developed to improve cochannel interference in cellular systems and most wireless
systems use three sector cells. [8]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
service area
The specified area over which the operator of a wireless
communications network or system provides services. [3]
Service Provider
A company that provides services and subscriptions to
telephone, mobile phone and Internet users. [2]
SFHMA
Slow Frequency Hopped Multiple
Access
A phenomenon that occurs when a mobile moves behind
an obstruction and experiences a significant reduction in
signal power.
shadow fading
SHF
A spread-spectrum system where the hop (dwell) time is
much greater the information symbol period. When
hopping is coordinated with other elements in the network,
the multiple access interference in the network is greatly
reduced. [2]
Super High Frequency
The RF spectrum between 3 GHz and 30 GHz. [1, 4]
Signal Booster
Compensates for loss of effect (weakening of the signal in
the co-axial cable) between the outer antenna and the
phone. Applies to both incoming and outgoing signals.
signal-to-interference ratio
The ratio of power in a signal to the interference power in
the channel. The term is usually applied to lower frequency
signals, such as voice waveforms, but can also be used to
describe the carrier wave. See also carrier-to-interference
ratio. [1]
signal-to-noise ratio
The ratio of power in a signal to the noise power in the
channel. This term is usually applied to lower frequency
signals, such as voice waveforms. See also carrier-to-noise
ratio. [1]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
SIM Card
Subscriber Identity Module Card
A small printed circuit board that must be inserted in any
GSM-based mobile phone when signing on as a subscriber.
It contains subscriber details, security information and
memory for a personal directory of numbers. A Subscriber
Identity Module is a card commonly used in a GSM phone.
The card holds a microchip that stores information and
encrypts voice and data transmissions, making it close to
impossible to listen in on calls. The SIM card also stores
data that identifies the caller to the network service
provider. [2]
slotted ALOHA
An access technique synchronizing the transmitters to
time-slots in the channel and having the transmitter wait
until the next available slot to send its packet. [1]
slow fading
A long term fading effect changing the mean value of the
received signal. Slow fading is usually associated with
moving away from the transmitter and experiencing the
expected reduction in signal strength.
SMR
Specialized Mobile Radio
A service defined by the FCC operating in the 800 MHz
and 900 MHz bands providing a variety of 2-way
communications services to various users. This is the basic
2-way trunked service used by many companies in the
construction and service industries. These frequencies are
gradually being converted to ESMR operation. [1]
SMS
Short Messaging Service (Service
Management System)
A store and forward message service available on most
second generation digital systems that allows short
messages (up to 140 octets) to be sent to the mobile and
displayed on a small screen. The control and signalling
channels are normally used to deliver these messages. [11]
SNR
Signal-to-Noise Ratio
See signal-to-noise ratio. [4]
soft handoff
A process of establishing a call connection simultaneously
to two separate base stations in a CDMA system. This
technique allows the use of a dual path in the handoff
region to improve performance. Soft handoff can only
occur between base stations using the same RF channel.
See also hard handoff. [4]
space diversity
A diversity technique widely used in wireless systems
since the very beginning. It consists of two receive
antennas physically (spatially) separated to provide
decorrelated receive signals. [4]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
spectrum spreading
The process of increasing the occupied spectrum of a
signal well beyond that needed to transmit the information.
[2]
speech coding
An electronic process of sampling and digitizing a voice
signal. [4]
spread spectrum
A term used to describe a system that uses spectrum
spreading techniques in its operation.
SR
Spread Rate
Spread rate is also known as the chip rate and is the rate of
the digital code used to spread the information. The
spreading rate is typically at least 100x the information
rate.
SS
Spread Spectrum
See spread spectrum.
SS7
Signal System 7
International standard protocol defined for open signaling
in the digital public switched network. It is based on a 64
kbps channel and allows for information transfer for call
control, database and billing management, and for
maintenance functions. [1]
SSD
Shared Secret Data
Part of an encryption process supporting authentication of
mobile phones. It uses an encryption key installed in the
phone at the time of activation and known to the system
through an entry in the HLR, that protects signalling and
identity information. It can also be used to establish a voice
privacy key. [1]
STD
Selective Transmit Diversity
A transmit diversity technique using multiple base stations
to originate the signal and provide spatial diversity on the
downlink. In STD, the transmitter selection is based on a
QoS measurement made at the mobile station. See also
transmit diversity, TDTD and TSTD. [1]
supplementary services
A group of network layer protocol functions that provide
call independent functions for mobile phones. These
include: call forwarding, follow-me, advice of charge,
reverse charging, etc.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
Symbian
Symbian is a bold new venture formed by Nokia, Ericsson,
Motorola, and Psion to create easy to use operating
systems for wireless devices and personal digital assistants
(PDAs). The first operating system is called EPOC and
was launched earlier this year.
Synchronous Mode
Type of transmission in which the transmission and
reception of all data is synchronized by a common clock
and transmitted in blocks rather than individual characters.
This mode gives higher data throughput than asynchronous
mode, but can be less secure. Synchronous mode does not
require a start and stop codes as in asynchronous mode.
Can also mean that the data stream has the same capacity
in both directions. See also asynchronous mode. [1]
TACS
Total Access Communications System An analog cellular communications system derived from
AMPS. It has been adopted in the UK (ETACS) and
operates in the 900 MHz band. Likewise adopted in Japan
first as JTACS, it exists at present as the further evolved
NTACS with narrower bandwidth. [1]
TAMS
Temporary Mobile Station Identity
An identification number assigned to a mobile station
while it is attached to the network. This number is
maintained in the VER and SIM while the mobile is
attached to the network and is used to route calls to and
from the mobile. [1]
TCH
Traffic Channel
A logical channel that allows the transmission of speech or
data. In most second generation systems, the traffic
channel can be either full or half-rate.
TCH/F
Traffic Channel - full rate
A traffic channel using full rate voice coding. [4]
TCH/H
Traffic Channel - half rate
A traffic channel using half rate voice coding.
TCM
Trellis Code Modulation
A type of channel coding that, unlike block and
convolutional codes, provide coding gain by increasing the
size of the signal alphabet and use multi-level phase
signalling.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
TCP
Transmission Control Protocol
TCP/IP is the standard communications protocol required
for computers communicating over the Internet. To
communicate using TCP/IP, computers need a set of
software instructions or components called a TCP/IP stack.
TDD
Time Division Duplex
A duplexing technique dividing a radio channel in time to
allow downlink operation during part of the frame period
and uplink operation in the remainder of the frame period.
See also duplex.
TDMA
Time Division Multiple Access
A technology for digital transmission of radio signals
between, for example, a mobile telephone and a radio base
station. In TDMA, the frequency band is split into a
number of channels which in turn are stacked into short
time units so that several calls can share a single channel
without interfering with one another. Networks using
TDMA assign 6 timeslots for each frequency channel.
TDMA is also the name of a digital technology based on
the IS-136 standard. TDMA is the current designation for
what was formerly known as D-AMPS. See also IS-136
and D-AMPS.
TDN
Temporary Directory Number
A temporary identification number assigned to a mobile
while attached to the network. [2]
TDTD
Time Division Transmit Diversity
A technique utilizing multiple transmit stations to originate
the downlink signal and improve performance. The
transmit station used can be determined by either a fixed
pattern or based on a QoS measurement made at the
mobile. See also STD and TSTD. [5]
TIA
Telecommunications Industry
Association (U.S.)
One of the Telecommunications standards setting bodies in
the United States. [1]
time dispersion
Time dispersion is a manifestation of multipath
propagation that stretches the signal in time so that the
duration of the received signal is greater than the
transmitted signal.
time diversity
The technique used by CDMA systems to overcome the
effects of multipath fading. Through the use of a rake
receiver, individual elements, or fingers, can be offset in
time to account for different arrival times of multipath
signals. [2]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
transceiver
A transmitter and receiver contained in one package. A 2way radio or cell phone is an example of a transceiver.
transmit diversity
A technique utilizing multiple transmit stations to originate
the downlink signal and improve performance. The station
used is determined by either a fixed pattern or a quality
measurement at the mobile. See also TDTD, STD and
TSTD.
transmitter
Equipment which feeds the radio signal to an antenna, for
transmission. It consists of active components such as the
mixer, driver and PA and passive components such as the
TX filter. Taken together, these components impress a
signal onto an RF carrier of the correct frequency by
instantaneously adjusting its phase, frequency, or
amplitude and provide enough gain to the signal to project
it through the ether to its intended target. [2]
triple mode (tri-mode)
A combined analog and digital mobile phone. Allows
operation of the phone in the existing analog system at 800
MHz and in digital systems at both 800 MHz and 1900
MHz. [2]
TSTD
Time Switched Transmit Diversity
A technique utilizing multiple transmit stations to originate
the downlink signal and improve performance. The
transmit station used is determined by a fixed selection
pattern similar to frequency hopping. See also STD and
TDTD. [2]
TTA
Telecommunications Technology
Association (Korea)
A telecommunications standards setting body in Korea.
TTC
Telecommunications Technology
Committee (Japan)
A private-sector corporate body established in 1985 to
prepare domestic standards relevant to Japanese
telecommunications.
Twisted Pair
UHF
Two insulated copper wires twisted together with the
"twists" or "lays" varied in length to reduce potential signal
interference between the pairs. Where cables comprise
more than 25 pairs, they are usually bundled together and
wrapped in a cable sheath. Twisted pair is the most
commonly used medium for connecting telephones,
computers and terminals to PABXs, supporting speeds up
to 64kbits/sec. [8]
Ultra High Frequency
The RF spectrum between 300 MHz and 3 GHz.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
UL
Uplink
See uplink.
UMTS
Universal Mobile Telecommunications Third generation telecommunications system based on WSystem
CDMA DS.
UNIX
A computer operating system. UNIX is designed to be used
by many people at the same time and has TCP/IP built-in.
It is a very common operating system for servers on the
Internet.
uplink
The transmission path from the mobile station up to the
base station.
UPT
Universal Personal Telecommunications A set of standards developed by the CCITT for wireline
personal communications. [1]
urban cells
The coverage provided by base stations located in urban
areas. The radius of these cells is usually much smaller
than suburban and rural cells due to the more difficult
propagation environment. [2]
USIM
An upgrade of the SIM card.
This upgrade enables use with IMT-2000.
UTRA
UMTS Terrestrial Radio Access
A W-CDMA standard developed ETSI, ARIB and the TIA.
This system uses DSSS and either FDD or TDD depending
on its frequency assignment and application. [2]
UUT
Unit Under Test
An acronym describing some type of electrical apparatus
connected to test instrumentation. The apparatus can range
from a simple circuit a complex subsystem such as a
mobile phone, base station or MSC. See also DUT.
UWC
Universal Wireless Consortium
Body of vendors and operators promoting and
implementing the IS-136 digital standard. Also specifying
the future development of the standard and facilitating
roaming agreements between IS-136 operators.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
VAD
voice activity detector
The device that detects voice activity and allows DTX to
operate. VAD, in conjunction with DTX reduces power
consumption in the mobile station and RF interference in
the system by muting the transmitter when there is no
voice to transmit.
VHF
Very High Frequency
The RF spectrum between 30 MHz and 300 MHz. [1]
Viterbi algorithm
VLR
A technique for searching a decoding trellis to yield a path
with the smallest distance. This is also known as maximum
likelihood decoding. [1]
Visitor Location Register
vocoder
The functional unit responsible for managing mobile
subscribers currently attached to the network. Two types of
information reside in the VLR: subscriber information and
the part of the mobile information that allows incoming
calls to be routed to the mobile subscriber. The VLR stores
the MSRN, TMSI, the location area, data on
supplementary services, IMSI, MS ISDN number, HLR
address or GT, and local MS identity, if used. [2]
Refers to a voice encoder which is a device that codes and
decodes the human voice (sound waves) into digital
transmission. Higher vocoder speeds offer enhanced sound
quality. [2]
VOIP
Voice Over Internet Protocol
A technology for transmitting ordinary telephone calls over
the Internet using packet-linked routes. VoIP is not simply
for voice over IP, but is designed to accommodate two-way
video conferencing and application sharing as well.
VPN
Virtual Private Network
A private telecommunications network created using the
resources of the PSTN and customized dialing, switching
and routing functions. [4]
VSELP
Vector Sum Excited Linear Predictive
A type of speech coding using an excitation signal
generated from three components: the output of a long term
or pitch filter and two codebooks. VSELP was used in the
IS-54 standard and operated at a rate of 8 kbps.
W3C
World Wide Web Consortium
A sector-wide body which promotes standardization of
WWW technology. Major Internet related vendors are
consortium members, and to date the body has
standardized a range of crucial technologies including
HTTP, HTML, XML, etc.
Wireless Dictionary
Acronym/Term
Acronym Definition
Walsh Code
Explanation
A group of spreading codes having good autocorrelation
properties and poor crosscorrelation properties. Walsh
codes are the backbone of CDMA systems and are used to
develop the individual channels in CDMA. For IS-95, here
are 64 codes available. Code 0 is used as the pilot and code
32 is used for synchronization. Codes 1 though 7 are used
for control channels, and the remaining codes are available
for traffic channels. Codes 2 through 7 are also available
for traffic channels if they are not needed. For cdma2000,
there exists a multitude of Walsh codes that vary in length
to accommodate the different data rates and Spreading
Factors of the different Radio Configurations. For more
information see Agilent application note "Performing
cdma2000 Measurements Today".
WAP
Wireless Application Protocol
A free, unlicensed protocol for wireless communications
that makes it possible to create advanced
telecommunications services and to access Internet pages
from a mobile telephone. WAP is a de facto standard that
is supported by a large number of suppliers. See also
http://www.wapforum.org
WCA
Wireless Communications Association The Wireless Communications Association represents the
fixed broadband wireless access industry worldwide. It's
mission is to advance the interests of the wireless systems
that provide data (including Internet and e-commerce),
voice and video services on a subscription basis through
land-based towers to fixed reception/transmit devices.
WCDMA
Wideband Code Division Multiple
Access
See W-CDMA.
W-CDMA
Wideband-Code Division Multiple
Access
A 3G radio interface using DSSS, and both Frequency
Division (FDD) and Time Division Duplexing (TDD)
depending on the frequency assignment. The earlier
Japanese W-CDMA trial system and the European UMTS
have both served as a foundation for the workings of the
current harmonized W-CDMA system, under the
supervision of the 3GPP. [2]
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
WDM
Wavelength Division Multiplexing
A new technology that uses optical signals on different
wavelengths to increase the capacity of fiber optic
networks in order to handle a number of services
simultaneously.
WLAN
Wireless Local Area Network
A wireless version of the LAN. Provides access to the
LAN even when the user is not in the office.
WLL
Wireless Local Loop
A wireless connection of a telephone in a home or office to
a fixed telephone network.
WML
Wireless Markup Language
A markup language developed specifically for wireless
applications. WML is based on XML.
WOS
Wireless Office Systems
A technology that allows the user to transfer calls to a
mobile telephone.
WPABX
Wireless Private Automatic Branch
Exchange
A customer premise telephone switching system using
wireless technology to link the individual user stations to
the central switching unit. The WPABX is capable of
interfacing to a telephone central office with trunk groups
and routing calls based on a 3 or 4 digit telephone
extension number.
X.25 protocol
XML
A CCITT recommendation defining the interface between
Data Terminal Equipment (DTE) and Data
Communications Equipment (DCE) operating in the packet
mode on public data networks. It is a set of 3 peer
protocols: a physical layer X.21), a link control layer
(HDLC) and a network layer. X.25 is based on the concept
of virtual circuits, which can be temporary or permanent.
[5]
Extensible Markup Language
XML is a format for structured documents and data. It was
developed by the World Wide Web Consortium (W3C). It
is a meta-language, i.e. content is not directly encoded in
XML but in a specific markup language defined using
XML. It corresponds to the successor language for the
current HTML. In contrast to HTML where tags are predefined, the XML user can freely extend a data format
applying his or her own uniquely defined tags. Since the
tag structure in the case of XML enables the computer to
automatically analyze data content, building EC (electronic
commerce) and EDI (electronic data interchange) systems
is facilitated.
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
1: Wireless and Personal Communications Systems, V. K. Garg and J. E. Wilkes, Prentice-Hall
2: Mobile Radio Communications, R. Steele and L. Hanzo, IEEE Press - Wiley
3: Mobile Communications Fundamentals and Applications, B. Sklar, Prentice-Hall
4: The Mobile Communications Handbook, J. Gibson, IEEE Press
5: Input received from Agilent
6: Digital Communications, J. Proakis, McGraw-Hill
7: The IEEE Standard Dictionary of Electrical and Electronic Terms, IEEE Std. 100 - 1996, Sixth
Edition, IEEE
8: Digital Telephony and Network Integration, B. Keiser and E. Strange, Van Nostrand Reinhold
9: Reference Data for Engineers, Seventh Edition, Howard W. Sams & Co.
10: Information, Transmission, Modulation & Noise, M. Schwartz, McGraw-Hill
11: Mobile and Personal Communications Systems and Services, R. Panya, IEEE Press
Wireless Dictionary
Acronym/Term
Acronym Definition
Explanation
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