during - University of Pittsburgh

Telcom 2700/INFSCI 1071
Wireless Networks
David Tipper
Associate Professor
Telecommunications Program
University of Pittsburgh
dtipper@mail.sis.pitt.edu
http://www.sis.pitt.edu/~dtipper/2700.html
Slides 1
Course Goals
• Provide students a understanding of the
structure, system aspects and protocols of
wireless networks.
• The focus in on the generations of cellular
networks, WirelessMANs, WirelessLANs,
and Wireless PANs.
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Text and Grading
• Text: Mobile Communications 2nd edition, Jochen Schiller,
Addison Wesley
also recommend
• Principles of Wireless Networks A Unified Approach, K.
Pahlavan and P. Krishnamurthy, Prentice Hall, 2002.
• Overview of wireless network architectures
– Will post many links to papers to fill in on newer developments
• Grading
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Homework + Labs (2 or 3 labs) 25%
Midterm
25%
Final Exam
30%
Term Project
20%
Group or individual project that involves a wireless network
technology
• Past Projects include
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Evaluation of battlefield WLAN implementation
WiMAX QoS planning techniques
Comparative evaluation of smart antenna techniques
Ad hoc extensions of cellular networks for disaster/fault recovery
Paper on Regulatory issues for software/cognitive radios
Paper on Health issues of wireless technology
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Course Outline
• Introduction (Ch 1)
– Overview or wireless networks, applications and issues
• Wireless communication fundamentals (Ch 2 -3)
– Frequencies, Propagation, Modulation and Antennas, (Ch 2, +
Notes)
– Mitigation Techniques and Multiple Access (Slides + Ch 3)
• Wireless Wide Area Networks
– Cellular Networks: (Slides + Ch 4)
• Voice oriented cellular (frequency reuse, traffic engineering, etc.
• GSM, cdmaone
• Data oriented cellular
– 2.5 G (GPRS) and 3G UMTS, cdma2000
– Satellite Networks (Ch 5)
– Location Technology
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Course Outline
• Wireless Local Area Networks (Ch 7)
– IEEE 802.11 standard and MAC layer
– Variations in a,b,g,n
• Wireless Personal Area Networks (Ch 7)
– IEEE 802.15, Bluetooth
– Zigbee and sensors
• Wireless Metro Area Networks (slides + notes)
– IEEE 802.16 (WiMAX)
• Application Development and higher layer
protocols (Ch 8, 10)
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Wireless Communication Systems
• Wireless Communication System:
– Any electrical communication system that uses a naturally
occurring communication channel, such as air, water, earth.
• Examples:
– Cell phone, Sonar, ground penetrating radar
– Broadcast: (one way)
• Radio, TV, pagers, satellite TV, etc.
– Two Way:
• walkie talkie, cell phones, satellite phones, wireless local
area networks, etc.
• Fundamentally different from wired networks
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Mobile vs. Wireless
• Wireless Communication System:
– Any electrical communication system that uses a naturally
occurring communication channel, such as air, water, earth.
• Mobile and Wireless are not interchangeable
Wireless vs. Mobile
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Examples
stationary computer, pay phone
calling card, call forwarding
wireless local loop
cell phone, laptop with WLAN
• Mobile wireless communication systems focus
– Communicate over the air via radio-waves
– Support some form of user mobility
• Examine how they are different from wired networks
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Wireless Issues
• Wireless link implications
– communications channel is the air
• poor quality: fading, shadowing, weather, etc.
• data rate and coverage vary
– regulated by governments
• frequency allocated, licensing, etc.
– limited bandwidth
• low bit rate, frequency planning and reuse, interference
– power issues
• Power levels regulated (safety issue), conserve mobile terminal
battery life
– security issues
• wireless channel is a broadcast medium!
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Mobility Issues
• Mobility Types
– User mobility : user can access network while mobile
• must handoff calls/connections in progress as user moves
• track users as they move so they can receive info/calls
– Service mobility: user’s services follow them
• Need to have authentication and services follow user
• Degree of Mobility
– Geographic range
• ranges from a house/apartment to worldwide
– Speed
• ranges from stationary to bullet train
• cordless phone vs. cell phone
• Mobility Æ portable device
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Device Issues
• Mobile Device Issues
– Portability
• Device and accessories size and weight
– Usability
• User characteristics (size, dexterity, knowledge, etc.)
• Environment characteristics (Temperature, degree of mobility,
etc)
• Device Characteristics
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startup time
data integrity and security
cpu speed and memory size
power supply
user interface (keypad, stylus, voice, etc.)
– Functionality (standalone, network dependent)
– Connectability (always, partial, never)
• In general have a limited power supply, user interface
and speed compared to stationary device
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Mobile Devices
Pager
• receive only
• tiny displays
• simple text
messages
•two way pagers
PDA/Smartphone
• graphical displays
• character recognition
• WWW
•Simple versions of
standard applications
Laptop and Tablet PC
• fully functional
• standard applications
Sensors,
embedded
controllers
Mobile phones
• voice, data
• simple text displays
• simplified WWW
Palmtop
• tiny keyboard
• simple versions
of standard applications
Performance and Cost
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Wireless Networks
– Wireless Wide Area Networks (WWANs)
• Cellular Networks :
– GSM, cdmaone (IS-95), UMTS, cdma2000 EVDO
• Satellite Networks:
– Iridium, Inmarsat, GPS, etc.
– Wireless Metro Area Networks (WMANs)
• IEEE 802.16 WiMAX
– Wireless Local Area Networks (WLANs)
• IEEE 802.11, a, b, g, etc. (infrastructure, ad hoc)
– Wireless Personal Area Networks (WPANs)
• IEEE 802.15 (Bluetooth), IrDa, Zigbee, sensor,
etc.
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Wireless Networks
Network
Geographic Coverage
Typical Throughput
Standards
WWANs
National, Continent wide
Worldwide
2G: 9.6 – 45 Kbps,
2.5G: 50 -300 Kbps
3G : 50kbsp- 2Mbps
3.5G: .1 – 20 Mbps
Satellite – 9.6 – 512Kbps
WMANs
Metro, suburb, campus 1- 100 Mbps – 10Gbps
15 km
WLANs
In building, campus wide,
subdivision wide,
Range ~ 100 M per AP
1-106 Mbps
IEEE 80211a, b, g, etc.
WPANs
5-10 M around device
.1 – 1Mbps
IEEE 802.15 IrDa,
BlueTooth, Zigbee
2G: GSM, cdmaone
2.5G: GPRS, cdma 2000 1X-rtt
3G: UMTS, cdma2000 1x-EDVO
3.5G: HSPDA
Proprietary
IEEE 802.16
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WWANs
• Mobile phone systems
– Support communication to mobile users via wireless
radio channel
– Fastest growing technical device EVER!
• Nokia sold over 120 million phones last year!
• More cell phones than wired phones
• More internet capable cell phones than PCs
– Variety of systems and standards:
• Analog 1G : NMT, AMPS, TACS
• Digital 2G: GSM, IS-95b (cdmaone),
• 3G: UMTS, cdma 2000
– Scope of services and coverage areas growing
• SMS, MMS, laptop data, etc.
• Focus now on wireless data and location aware services
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Cellular Network Architecture
• Cell : Area covered by 1 radio tower unit (base station)
• Cellular Systems:
• provide wireless coverage to a geographic area with a set of
slightly overlapping cells. Use a set of low power radio stations to
provide coverage, each cell has different set of frequencies or
codes, support handoff of mobile from one cell to another, track
mobile for incoming call
Cell coverage, size and actually shape
depends on local geography, power
level, cell site height, antenna type, etc.
Hexagonal idealized
cell shape
cell
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Cellular Network Architecture
HLR
AUC
Wired or
Backhaul
network
MSC
VLR
BSC
GMSC
VLR
Public Switched
Telephone Network
MSC
BSC
• Cellular Network Components
• Mobile Station (Terminal) – handset
Wireless
(radio)
part
Base Station
• Base Station (cell site)
• Base Station Controller (BSC)
• Mobile Switching Center (MSC)
•Gateway MSC (interface to wired phone)
• Home Location Register (HLR)
• Visitor Location Register (VLR)
• Authentication register (AUC)
• HLR/VLR/AUC databases to track, bill
and authentic users
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2G Cellular Network Architecture
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Cell Phone Market
• Stratification of market
• Teenage
• Safety/children
• Business – low end
• Business – high end
• Families
• Luxury
• Improvements in
• display technology
• memory
• cpu speed
• Smaller devices greater
functionality Î merger with
other portable devices or
accessories
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2.5/3G/WLAN Mobile Devices
• More Internet-friendly
interface
– Wide, color screens
• More flexible to support new
applications
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Voice
Video telephony capabilities
Web browsing
Web Games
Electronic postcards
Location-based services
Streaming applications
• Various I/O modes/interfaces
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Keypad,
voice recognition,
character recognition,
pen based, etc.
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Handset Market
• Top Ten Phones in US during 1/01-10/30/07
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Motorola RAZR V3
Motorola RAZR V3m
LG VX8300
Apple iPhone
LG Chocolate VX8550/8500
Motorola MOTOKRZR K1m
Samsung SGH-A707
LG VX5300
Sanyo Katana II
Motorola V323i/V325i
• Still a wide variety of phones and capabilities –
high end PDA type phones minority
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Base Stations
• Base Station (BS)
Provides radio channels between mobile units and network
Pico-cells : (indoor – 0-.5 Km) support 8-20 channels
micro-cells: (outdoor – 0-1 Km), macro-cells: (1-30 Km)
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Base Stations
• Base Transceiver Station (BTS) - houses radio units
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Base Station Controller
• Base Station Controller (BSC)
Manages a cluster of BS, channel assignment,
handoff, power control, some switching, etc
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Mobile Switching Center
• Mobile Switching Center (MSC) (MTSO)
– Provides switching functions , coordinates location tracking,
call delivery, handoff, interfaces to HLR,VLR, AUC, etc..
– Size of central office switch
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HLR/VLR
• Home Location Register (HLR)
– Specialized database server contains billing info, service profile
and general location of a mobile user (one per service provider or
one per section of country)
– Visitor Location Register (VLR) similar to HLR contains location of
users and their service profile of all users in a metro type area
(one per MSC)
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WWANS - Satellites
• Over 3500 Satellites in use today - industry overall
revenues of $2.3 billion in 2004
• Telecommunications
– global telephone connections
being replaced by fiber optics
– backbone for global networks
– connections for communication in remote places or
underdeveloped areas
– global mobile communications
• Other Applications
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weather
radio and TV broadcast satellites
Earth observation (climate change, agricultural, etc.)
military: surveillance, imaging, intelligence, early warning
Navigation and localization: aeronautic, nautical, etc., (e.g., GPS,
NavStar)
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Satellite Basics
• Components
• Earth (ground) Stations – antenna systems on or near
earth
• Uplink – transmission from an earth station to a satellite
• Downlink – transmission from a satellite to an earth
station
• Typically separated frequencies for uplink and
downlink (FDD)
• Transponder – electronics in the satellite that convert
uplink signals to downlink signals
– transparent transponder: only shift of frequencies (Bent Pipe)
– regenerative transponder: additionally signal regeneration and
formatting) Processing Satellite
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Typical Satellite System
Inter Satellite Link (ISL)
Mobile User
Link (MUL)
Gateway Link
(GWL)
MUL
GWL
small cells
(spotbeams)
base station
or gateway
footprint
ISDN
PSTN: Public Switched
Telephone Network
PSTN
Cellular
User data
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Wireless MANs
• Wireless Metropolitan Area Networks (WMANs) : provide wireless
connectivity across a geographical area the size of a city
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Wireless MANs
• Wireless Metropolitan Area Network (WMAN)
– Wireless alternative to DSL/cable modem/Fiber to the
Home) services for last mile broadband access.
– Point to Multipoint (PMP) protocol
– Scope expanded to include mobility and higher data
rates
– IEEE 802.16 standard
– Worldwide Interoperability for Wireless Microwave
Access (WiMAX)
• Both licensed and unlicensed spectrum
deployment
• Advantages: cost, flexibility, mobility
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IEEE 802.16 /WiMAX Standard
• Characteristics of 802.16
– Point to Multipoint (PMP) and Mesh protocol
– NLOS wireless broadband services including bandwidth on
demand
– QoS support
– Security
– Scope expanded to include mobility and higher data rates
• Focus on both licensed and unlicensed spectrum
deployment – supports multiple service providers/licenses
in same area
• 802.16 Terminology
– Base Station (BS) is WiMAX cell site/access point
– Subscriber Station (SS) is customer premise equipment and
terminates the wireless link to the user location
– Mobile Station (MS) is a standalone consumer device equipped
with a WiMAX radio
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WiMAX Architecture
Non Line-of-Sight
Point to Multi-Point
802.16d
Line-of-Sight
Backhaul
802.16
Telco Core
Network or
Private (Fiber)
Network
INTERNET
BACKBONE 32
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WiMax Applications
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5.
„
According to WiMax Forum it
supports 5 classes of applications:
Multi-player Interactive Gaming.
VOIP and Video Conference
Streaming Media
Web Browsing and Instant
Messaging
Media Content Downloads
Basically the Triple Play
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Wireless LANs
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Wireless Local Area Networks
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Support communication to mobile data users via
wireless channel
Types of WLAN
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Infrastructure based (most popular)
Connect users to a wired infrastructure network
Wireless access network like cellular phone system
IEEE 802.11, a, b, g , n
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3.
Ad-Hoc based networks
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Provide peer to peer communication – mobiles communicate
between each other directly
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Rapid Deployment (conference room)
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IEEE 802.11, a, b, g , n, Proprietary
Point – to –Point (cable replacement!)
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WLAN components
Wireless Fidelity standards for
Interoperability
Components: access points,
antennas, mobile stations
- 300 manufacturers
- www.wirelessethernet.org
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IEEE 802.11 Terminology
• Access Point (AP)
– Provides access to distribution services via the wireless
medium
• Basic Service Area (BSA)
– The coverage area of one access point
• Basic Service Set (BSS)
– A set of mobile stations controlled by one access point
• Distribution system
– The fixed (wired) infrastructure used to connect a set of BSS to
create an extended service set (ESS)
• Portal(s)
– The logical point(s) at which non-802.11 packets enter an ESS
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WLAN Topologies
ad-hoc based architecture
Point-to-point
Infrastructure based architecture
ESS
BSS 1
BSS 2
WT 1
WT 2
WT 3
AP 1
AP 2
Wired-distribution network
WT 4
AP 3
WT 5
BSS = Basic Service Set
ESS = Extended Service Set
AP = Access Point
WT = Wireless Terminal
BSS 3
Basic Service Area (BSA)
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Communication link
Wireless Personal Area Network
• Origins in the BodyLAN project initiated by BBN in the
early 1990s
• Networking “personal” devices – sensors, cameras,
handheld computers, audio devices, etc. with a range of
around 5 feet around a soldier
• Today: Networking digital cameras to cell phones to
PDAs to laptops to printers to etc..,
• Most popular application – hands free headset to
cellphone
• IEEE 802.15 standard (Bluetooth)
– Use band available globally for unlicensed users
– Low powered – medium data rate ~100s kbps
– Subgroups doing higher data rates and sensors (Zigbee)
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Applications of WPANs
Cable Replacement
Ad hoc connectivity
(b)
(a)
Access to wired
network
PSTN
PSTNor
or
the
the
Internet
Internet
(c)
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Wireless Networks
– Wireless Wide Area Networks (WWANs)
• Cellular Networks :
– GSM, cdmaone (IS-95), UMTS, cdma2000 EVDO
• Satellite Networks:
– Iridium, Inmarsat, GPS, etc.
– Wireless Metro Area Networks (WMANs)
• IEEE 802.16 WiMAX
– Wireless Local Area Networks (WLANs)
• IEEE 802.11, a, b, g, etc. (infrastructure, ad hoc)
– Wireless Personal Area Networks (WPANs)
• IEEE 802.15 (Bluetooth), IrDa, Zigbee, sensor,
etc.
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Example Network Architecture
WWAN
LEGEND
Public Switched
Telephone or Public
Data Network
Laptops
Handheld PCs
Switch & mobility and
radio resource
management
Switch
LAN Segment
Base Station
Multimedia terminal
WLAN
Vertical or Inter-tech
Handoff
Access Point
Router
Horizontal or Intratech Handoff
Cell
WPAN
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Evolving Applications
• Focus on data based services and value added
applications
– Mobile Internet Access
– Mobile Intranet/Extranet Access
– Personalized Infotainment
• Video, audio, games, etc.
– Multimedia Message Service (MMS)
– Location Based Services (LBS)
– Rich Voice
• Theme
– MultiMulti-mode (multi(multi-media) service
– Community and identity
Facebook Mobile
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Enablers
• Wireless network development
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Increased bandwidth/data rate
Falling costs
Always on capability
WLAN – hotspots
• Mobile Devices
– Fast development
– More connectivity, computing power and autonomy, but lower
size, weight and cost
– More functionality – camera, mms, radio, gps, compass
• Software Infrastructure
– wap, xml, VXML, J2ME, .NET CF, Device emulators, etc.
– Smart Clients
• mobile databases, synchronization technology
• Standardization
– Software, protocols and hardware (e.g., Bluetooth). etc..
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Example: Expert on Call
Something doesn’t
seem right. Am I testing
the right circuit?
This is the one I’m
working on.
No, that’s not the correct
one. Scan to the left,
I’ll tell you to stop when
you get to the right spot.
Expert technician at field site #2.
Less experienced technician at field site #1.
Streaming Media, Real-time voice, Best Effort Data Convergence
Feasible with 3G technology
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Example Application
After one week…
I am going to
teach my
phone my
habits.
Looks cool!
Marie buys a new phone. She is
showing it to her friend Susie.
The device has learnt where Marie likes to visit and what she does.
Your phone is
beeping
Marie gives names to positions.
Look, it
remembers!
Marie leaves to work, surprised that her phone helped her not to be late.
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Summary
• Overview of Wireless Networks
– WWANs (cellular, satellite)
– WMANs (802.16 - wiMAX)
– WLANs (802.11)
– WPANs (802.15)
• Mobile Applications
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