-introduction-to-cellular-mobile-communications

Cellular Mobile Communications-Cellular Mobile Communications-
II
An IntroductionAn Introduction
Dr. Nasir D. GoharDr. Nasir D. Gohar
http://www.stanford.edu/class/ee359/lectures.html
Lecture Notes by Professor Reynold Cheung
Other Internet Resources
www.nmscommunications.com

Cellular Mobile Communications-ICellular Mobile Communications-I
Cell Phone Growth in Pakistan & WorldwideCell Phone Growth in Pakistan & Worldwide
 According to a Media Report (Goliath, May 25, 2005), CellAccording to a Media Report (Goliath, May 25, 2005), Cell
Phones in Pakistan to Touch 15M mark in December 2005Phones in Pakistan to Touch 15M mark in December 2005
 Another Media Report (Middle East Times, June 20, 2006)Another Media Report (Middle East Times, June 20, 2006)
Predicts the number of Cell Phones will rise from 2.2 Billion to 3Predicts the number of Cell Phones will rise from 2.2 Billion to 3
Billion worldwide by the end of Year 2008Billion worldwide by the end of Year 2008
 According to MOBILEDIA (Jan 20, 2006)According to MOBILEDIA (Jan 20, 2006)
 U.S. offers more room for growth than Russia, and Japan offers greaterU.S. offers more room for growth than Russia, and Japan offers greater
future growth than South Africafuture growth than South Africa
 The number of mobile subscribers worldwide reached over 2 billion by theThe number of mobile subscribers worldwide reached over 2 billion by the
end of 2005, and is predicted to rise to 3.96 billion by 2011end of 2005, and is predicted to rise to 3.96 billion by 2011
 The Asia Pacific Region will account for 50% of the total number ofThe Asia Pacific Region will account for 50% of the total number of
subscribers worldwide by the end of this decade with a staggering 1.067subscribers worldwide by the end of this decade with a staggering 1.067
billion subscribers shared between China and India alone, the world's twobillion subscribers shared between China and India alone, the world's two
biggest mobile marketsbiggest mobile markets

Several Types of Mobile Radio SystemsSeveral Types of Mobile Radio Systems
 Garage Door Controller [<100 MHz]Garage Door Controller [<100 MHz]
 Remote Controllers [TV/VCR/DISH][Infra-Red: 1-100 THz]Remote Controllers [TV/VCR/DISH][Infra-Red: 1-100 THz]
 Cordless Telephone [<100 MHz]Cordless Telephone [<100 MHz]
 Hand-Held Radio [Walki-Talki] [VHF-UHF:40-480 MHz]Hand-Held Radio [Walki-Talki] [VHF-UHF:40-480 MHz]
 Pagers/Beepers [< 1 GHz]Pagers/Beepers [< 1 GHz]
 Cellular Mobile Telephone[<2 GHz]Cellular Mobile Telephone[<2 GHz]
ClassificationClassification
 Simplex System:Simplex System: Communication is possible in only one direction :Communication is possible in only one direction : Garage DoorGarage Door
Controller, Remote Controllers [TV/VCR/DISH] Pagers/BeepersController, Remote Controllers [TV/VCR/DISH] Pagers/Beepers
 Semi-Duplex System:Semi-Duplex System: Communication is possible in two directions but one talksCommunication is possible in two directions but one talks
and other listens at any time[Push to Talk System]: Walki-Talkiand other listens at any time[Push to Talk System]: Walki-Talki
 Duplex SystemDuplex System:: Communication is possible in both directions at any time: CellularCommunication is possible in both directions at any time: Cellular
Telephone [FDD or TDD]Telephone [FDD or TDD]

Paging System:Paging System: For Transmission ofFor Transmission of Brief Numeric/Alpha-Brief Numeric/Alpha-
numeric/Voice Messages [Pages] to Subscribernumeric/Voice Messages [Pages] to Subscriber
 To Notify/Alert the UserTo Notify/Alert the User
 Simplex ServiceSimplex Service
 Modern Paging Systems Can Send News Head-Lines, Stock Info, or FaxModern Paging Systems Can Send News Head-Lines, Stock Info, or Fax
 Application Dependent System Range [2 Km to World-wide]Application Dependent System Range [2 Km to World-wide]
PAGING CONTROL
CENTRE
Paging Terminal
PSTN
Land Line Link
Land Line Link
Paging Terminal
Paging Terminal
City 1
City 2
City N

Cordless Telephone System:Cordless Telephone System: To Connect a FixedTo Connect a Fixed
Base Station to a Portable Cordless HandsetBase Station to a Portable Cordless Handset
 Early Systems (1980s) have very limited range of few tens ofEarly Systems (1980s) have very limited range of few tens of
meters [within a House Premises]meters [within a House Premises]
 Modern SystemsModern Systems [PACS, DECT, PHS, PCS][PACS, DECT, PHS, PCS] can provide acan provide a
limited range & mobility within Urban Centerslimited range & mobility within Urban Centers
PSTN
Fixed Base
Station
Cordless Handset

Limitations of Simple Mobile Radio SystemsLimitations of Simple Mobile Radio Systems
The Cellular ApproachThe Cellular Approach
 Divides the Entire Service Area into Several Small CellsDivides the Entire Service Area into Several Small Cells
 Reuse the FrequencyReuse the Frequency
Basic Components of a Cellular Telephone SystemBasic Components of a Cellular Telephone System
 Cellular Mobile PhoneCellular Mobile Phone :: A light-weight hand-held set which is anA light-weight hand-held set which is an
outcome of the marriage of Graham Bell’s Plain Old Telephoneoutcome of the marriage of Graham Bell’s Plain Old Telephone
Technology [1876] and Marconi’s Radio Technology [1894] [although aTechnology [1876] and Marconi’s Radio Technology [1894] [although a
very late delivery but very cute]very late delivery but very cute]
 Base StationBase Station :: A Low Power Transmitter, other Radio EquipmentA Low Power Transmitter, other Radio Equipment
[Transceivers] plus a small Tower[Transceivers] plus a small Tower
 Mobile Switching Center [MSC] /Mobile TelephoneMobile Switching Center [MSC] /Mobile Telephone
Switching Office[MTSO]Switching Office[MTSO]
 An Interface between Base Stations and the PSTNAn Interface between Base Stations and the PSTN
 Controls all the Base Stations in the Region and Processes User ID andControls all the Base Stations in the Region and Processes User ID and
other Call Parametersother Call Parameters
 A typical MSC can handle up to 100,000 Mobiles, and 5000 SimultaneousA typical MSC can handle up to 100,000 Mobiles, and 5000 Simultaneous
CallsCalls
 Handles Handoff Requests, Call Initiation Requests, and all Billing & SystemHandles Handoff Requests, Call Initiation Requests, and all Billing & System
Maintenance FunctionsMaintenance Functions

 The Cellular ConceptThe Cellular Concept
RF spectrumRF spectrum is a valuable and scarce commodityis a valuable and scarce commodity
RF signals attenuate over distanceRF signals attenuate over distance
Cellular network divides coverage area into cellsCellular network divides coverage area into cells, each, each
served by its own base station transceiver and antennaserved by its own base station transceiver and antenna
Low (er) power transmitters used by BSs; transmissionLow (er) power transmitters used by BSs; transmission
range determines cell boundaryrange determines cell boundary
RF spectrum divided into distinct groups of channelsRF spectrum divided into distinct groups of channels
Adjacent cells are (usually) assigned different channelAdjacent cells are (usually) assigned different channel
groups to avoid interferencegroups to avoid interference
Cells separated by a sufficiently large distance to avoidCells separated by a sufficiently large distance to avoid
mutual interference can be assigned themutual interference can be assigned the same channel groupsame channel group ⇒⇒
frequency reusefrequency reuse among co-channel cellsamong co-channel cells

 An Example of Frequency ReuseAn Example of Frequency Reuse
 Suppose we have spectrum
for 100 voice channels
 Scenario 1: a high power
base station covering entire
area – system capacity = 100
channels
 Scenario 2: divide spectrum
into 4 groups of 25 channels
each; cells (1, 7), (2, 4), (3,
5), 6 are assigned distinct
channel groups – system
capacity = 175 channels

Frequency Reuse FactorFrequency Reuse Factor
 Frequency Reuse Factor N = No. of Distinct Channel Groups = Maximum Cluster Size

Frequency Reuse Example-2Frequency Reuse Example-2
 SupposeSuppose WW = 25 MHz and= 25 MHz and BB = 25 KHz/voice channel= 25 KHz/voice channel
 W/BW/B = 1000 voice channels can be supported over the spectrum= 1000 voice channels can be supported over the spectrum
 Scenario 1:Scenario 1: a high power base station covering entire area (a high power base station covering entire area (MM == NN ==
1)1) ⇒⇒ system capacitysystem capacity nn = 1000 users= 1000 users
 Scenario 2:Scenario 2:
 Coverage area divided intoCoverage area divided into MM = 20 cells with reuse factor= 20 cells with reuse factor NN = 4= 4
 Each cluster accommodate 1000 active usersEach cluster accommodate 1000 active users
 5 clusters in coverage area5 clusters in coverage area ⇒⇒ system capacitysystem capacity nn = 5000 users= 5000 users
 MM = 100 cells,= 100 cells, NN = 4= 4 ⇒⇒ system capacitysystem capacity nn = 25000 users= 25000 users
 MM = 100 cells,= 100 cells, NN = 1= 1 ⇒⇒ system capacitysystem capacity nn = 100000 users= 100000 users

 Common Air Interface (CAI)Common Air Interface (CAI)
Forward Channel
Reverse Channel
Common Air Interface: A
Standard that defines Communication
between a Base Station and Mobile
Specifies Four Channels [Voice
Channels and Control / Setup
Channels]
FVC: Forward Voice Channel
RVC: Reverse Voice Channel
FCC: Forward Control Channel
RCC: Reverse Control Channel

 Call Setup ProcedureCall Setup Procedure
Cellular Phone Codes: Special Codes are associated with each Cell
Phone to identify the phone, its owner, and service provider:
Electronic Serial Number(ESN) -A Unique 32-bit Code
Mobile Identification Number(MIN): A Subscriber’s Telephone Number
 Station Class mark (SCM): Indicates the Max Tx Power for the User
When a Cellular Phone is turned on and Initiates a Call:[see
next slide]
Monitors the Control Channels and gets hold on to the strongest one
Makes a Call Initiation Request[Dials the Called part Number, MIN , ESN and SCM
automatically transmitted]
Validation Procedure at MSC & Voice-Frequency pair Allocation
Base Station Pages the Information for the Mobile
MSC Connects the Mobile with the Called Party[Another Mobile/Landline Phone]
Call is Established and Communication Starts

 Call Setup Procedure (Cont’d)Call Setup Procedure (Cont’d)
MSC
3. Receives a Call
Initiation Request from
Base Station, and
Verifies that User has a
Valid MIN & ESN pair
4. Locates the
Called Party,
Allocates a VFPs
and Instructs the
Base Stations via
FCC
7. Connects the
Called Party[on
PSTN]/Mobile to the
Mobile
FCC
5. Pages for the Called
Mobile, the Mobiles are
instructed to move to the
Allocated VFPs
respectively
RCC
2. Receives a Call
Initiation Request, with
MIN, ESN, SCM and
Called Part Number
FVC
8. Begins Voice
Transmission
RVC
8. Begins Voice
Reception
FCC
6. Receives [Called
Mobile] the Page and
Matches the MIN, the
Mobiles get ready to
move to the respective
Allocated VFPs
RCC
1. Makes a Call Initiation
Request, with MIN and
Called Part Number
FVC
8. Begins Voice
Reception
RVC
8. Begins Voice
Transmission
Base Station
Mobile
TIME

 Handoff and RoamingHandoff and Roaming
Handoff
When a Mobile is on the edge of a Cell
RSL of the Mobile in that Cell gets bellow a set Level
Base Station of the Cell originates a Handoff request
MSC gets RSL Info from all the Candidate Cells
MSC asks the Originating Cell and the Strongest
Candidate Cell to Coordinate
In Case the Handoff is Successful, the Mobile is asked
to switch to another VFP
All this happens in a matter of seconds and you hear a
little CLICK sound
Roaming
When SID of the Control Channel and that
programmed in the Mobile does not match:
The Mobile is in another Service Provider’s Area
MSC of the Cell contacts the MSC of the Mobile’s
Home System
After Verification, if the Mobile is Allowed, the new
MSC is ready to Serve.
MSC

 Comparison of Common Wireless CommunicationComparison of Common Wireless Communication
SystemsSystems
System
Coverage
Range
Required
Infra-
Structure
Complexity
Hardware
Cost
Carrier
Frequency
Functionality
Tv Remote Control Low Low Low Low Infra-Red Tx/Rx
Garage Door Contol Low Low Low Low <100 Mhz Tx/Rx
Paging System High High Low/High Low/High <1GHz Rx/Tx
Cordless Phone Low Low Moderate/Low Low/Moderate <100 MHz Transceiver
Cellular Phone High High High Moderate/High <1 GHz Transceiver
Tx = Transmitter Rx = Receiver
Comparison of Mobile Communication Systems - Mobile/Base Station

 Cellular Mobile Access TechnologiesCellular Mobile Access Technologies
FDMA Assigns each Call a Separate Frequency
Works like Radio Stations
Mainly Analogue Technology-used by AMPS, NAMPS, E-TACS, NMT-450, JTACS
Not an Efficient Method for Digital Transmission
849 MHz
869 MHz

TDMA Assigns each Call a
certain Time-Slot on a Designated
Frequency
Each Mobile/User gets one-third of
a total Channel Time-Slot[6.7 ms]
Courtesy of Compression
Techniques: Speech Data in Digital
Form takes considerably less time
Optimal Frequency Usage: System
Capacity improves by three times
Operates both in 800 MHz[IS-54]
and 1900 MHz[IS-136]
Digital Access Technology use by
GSM, USDC, IDEN, PDC and PCS

CDMA Assigns a Unique Code to
each Call and Spreads it over the entire
bandwidth available
 A form of Spread Spectrum
Technology
Speech Data is sent in small pieces
over number of Discrete Frequencies
available at any time in a specified range
 Receiver uses the same unique Code
to Recover the Speech Data
GPS used for Exact Time Stamp
Can handle 8-10 Calls in the same
Channel Space as one Analogue Channel
An Access Technology for 3G Mobile
Systems[IMT-2000]
Supports both Bands [800 MHz and
1900 MHz]

 Cellular System vs. Personal CommunicationCellular System vs. Personal Communication
System/Network (PCS/PCN)System/Network (PCS/PCN)
 Personal Communication Services [Personal Communication Services [PCSPCS] is a system, very similar] is a system, very similar
to Cellular Phone Service with great emphasis onto Cellular Phone Service with great emphasis on personalpersonal
servicesservices (such as Paging, Caller ID, and E-mail] and(such as Paging, Caller ID, and E-mail] and mobilitymobility
 Originated in UK,Originated in UK, to improve its competitiveness in the fieldto improve its competitiveness in the field
 PCSPCS has smaller Cell size, therefore, requires more infra-structurehas smaller Cell size, therefore, requires more infra-structure
 PCS works in 1.85-1.99 GHz bandPCS works in 1.85-1.99 GHz band
 PCS uses TDMA Technology but with 200 KHz ChannelPCS uses TDMA Technology but with 200 KHz Channel
Bandwidth with eight time-slots[as compared to 30 KHz and 3Bandwidth with eight time-slots[as compared to 30 KHz and 3
time-slots used by Digital Cellular Phone System IS-54/IS-136]time-slots used by Digital Cellular Phone System IS-54/IS-136]
 GSM and Cellular Digital Packet Data[CDPD] also use PCS Tech.GSM and Cellular Digital Packet Data[CDPD] also use PCS Tech.

 Dual Band/Dual Mode Cellular PhonesDual Band/Dual Mode Cellular Phones
Dual Band PhoneDual Band Phone:: Supports both bands 800 MHz andSupports both bands 800 MHz and
1900 MHz1900 MHz
Dual Mode Phone:Dual Mode Phone: Supports both FDMA and TDMASupports both FDMA and TDMA
AccessAccess TechnologiesTechnologies
Dual Band/Dual Mode PhoneDual Band/Dual Mode Phone:: Supports both BandsSupports both Bands
and Both Access Technologiesand Both Access Technologies
Tri-Mode Phone:Tri-Mode Phone: It can Support FDMA/TDMA/CDMAIt can Support FDMA/TDMA/CDMA
all Access Tech. A popular version of Tri-Mode Cellular Phone isall Access Tech. A popular version of Tri-Mode Cellular Phone is
the one which supports GSM [800 MHz as well as 1900 MHzthe one which supports GSM [800 MHz as well as 1900 MHz
(USA version)] as well as FDMA.(USA version)] as well as FDMA.

 Trends in Cellular radio and PersonalTrends in Cellular radio and Personal
CommunicationsCommunications
 PCS/PCN:PCS/PCN: PCS calls for more personalized services whereasPCS calls for more personalized services whereas
PCN refers to Wireless Networking Concept-any person,PCN refers to Wireless Networking Concept-any person,
anywhere, anytime can make a call using PC. PCS and PCNanywhere, anytime can make a call using PC. PCS and PCN
terms are sometime used interchangeablyterms are sometime used interchangeably
 IEEE 802.11IEEE 802.11 :: A standard for computer communications usingA standard for computer communications using
wireless links[inside building].wireless links[inside building].
 ETSI’s 20 Mbps HIPER LAN:ETSI’s 20 Mbps HIPER LAN: Standard for indoor WirelessStandard for indoor Wireless
NetworksNetworks
 IMT-2000 [International Mobile Telephone-2000IMT-2000 [International Mobile Telephone-2000
StandardStandard ]:]: A 3G universal, multi-function, globally compatibleA 3G universal, multi-function, globally compatible
Digital Mobile Radio Standard is in makingDigital Mobile Radio Standard is in making
 Satellite-based Cellular Phone SystemsSatellite-based Cellular Phone Systems
 A very goodA very good ChanceChance for Developing Nationsfor Developing Nations to Improveto Improve
their Communication Networkstheir Communication Networks

 Important First Generation Analog SystemsImportant First Generation Analog Systems
TypeType AMPSAMPS ETACSETACS NTTNTT
RegionRegion AmericaAmerica EuropeEurope JapanJapan
Multiple accessMultiple access FDMAFDMA FDMAFDMA FDMAFDMA
DuplexingDuplexing FDDFDD FDDFDD FDDFDD
Forward bandForward band 869 - 894 MHz869 - 894 MHz 935 – 960 MHz935 – 960 MHz 870 – 885870 – 885
MHzMHz
Reverse bandReverse band 824 – 849 MHz824 – 849 MHz 890 – 915 MHz890 – 915 MHz 925 – 940925 – 940
MHzMHz
Channel spacingChannel spacing 30 KHz30 KHz 25 KHz25 KHz 25 KHz25 KHz
No. of channelsNo. of channels 831831 10001000 600600

 Important Second Generation Digital SystemsImportant Second Generation Digital Systems
TypeType IS-54IS-54 IS-95IS-95 GSMGSM PDCPDC
RegionRegion AmericaAmerica AmericaAmerica EuropeEurope JapanJapan
MultipleMultiple
accessaccess
/Duplexing/Duplexing
TDMA/FDDTDMA/FDD CDMA/FDDCDMA/FDD TDMA/FDDTDMA/FDD TDMA/FDDTDMA/FDD
ModulationModulation ππ/4 DQPSK/4 DQPSK QPSK/OQPSKQPSK/OQPSK GMSKGMSK ππ/4 DQPSK/4 DQPSK
Forward BandForward Band 869 - 894 MHz869 - 894 MHz 869 - 894 MHz869 - 894 MHz 935 – 960 MHz935 – 960 MHz 810 – 826 MHz810 – 826 MHz
Reverse BandReverse Band 824 – 849 MHz824 – 849 MHz 824 – 849 MHz824 – 849 MHz 890 – 915 MHz890 – 915 MHz 940 – 956 MHz940 – 956 MHz
ChannelChannel
SpacingSpacing
30 KHz30 KHz 1.25 MHz1.25 MHz 200 KHz200 KHz 25 KHz25 KHz
Data/chip RateData/chip Rate 48.6 Kbps48.6 Kbps 1.2288 Mcps1.2288 Mcps 270.833 Kbps270.833 Kbps 42 Kbps42 Kbps
Codec RateCodec Rate
KbpsKbps
7.957.95 1.2/2.4/4.8/9.61.2/2.4/4.8/9.6 13.413.4 6.76.7
Users/channelUsers/channel 33 Up to 55Up to 55 88 33

 Difference Between First & Second GenerationDifference Between First & Second Generation
SystemsSystems
Traffic Channels –Traffic Channels – 1G systems use analog FM1G systems use analog FM
modulation; 2G systems use low bit-rate voice coding andmodulation; 2G systems use low bit-rate voice coding and
digital transmissiondigital transmission
Channel Access –Channel Access – 2G systems allow each frequency2G systems allow each frequency
channel to be shared by a number of users, using TDMA orchannel to be shared by a number of users, using TDMA or
CDMA techniquesCDMA techniques
Error Detection and Correction –Error Detection and Correction – 2G digital traffic2G digital traffic
channels incorporate FEC for error detection and correction,channels incorporate FEC for error detection and correction,
giving higher power and bandwidth efficiencygiving higher power and bandwidth efficiency
Encryption –Encryption – all 2G systems provide encryption toall 2G systems provide encryption to
prevent eavesdroppingprevent eavesdropping

 World-wide Subscriber Base as a Function ofWorld-wide Subscriber Base as a Function of
Technology (June 2006)Technology (June 2006)

 GSM (Global System for Mobile)GSM (Global System for Mobile)
 « « GroupGroupee Special MobileSpecial Mobile » later changed to « Global System for » later changed to « Global System for
Mobile »Mobile »
 Developed by ETSI as a pan-European 2G mobile standardDeveloped by ETSI as a pan-European 2G mobile standard
 Standard activity started in 1982, deployed in 1992Standard activity started in 1982, deployed in 1992
 A complete system standard for ISDN-like mobile servicesA complete system standard for ISDN-like mobile services
 Time division multiple access (8 users per 200KHz)Time division multiple access (8 users per 200KHz)
 900 MHz band; later extended to 1800MHz900 MHz band; later extended to 1800MHz
 Added 1900 MHz (US PCS bands)Added 1900 MHz (US PCS bands)
 GSM is dominant world standard todayGSM is dominant world standard today
•Well defined interfaces; many competitorsWell defined interfaces; many competitors
•Tri-band GSM phone can roam the world todayTri-band GSM phone can roam the world today

 GSM Growth – From 1993 to June 2006GSM Growth – From 1993 to June 2006

 North American StandardsNorth American Standards
Published by the Telecommunications IndustryPublished by the Telecommunications Industry
Association (TIA) as “Interim Standards” (IS)Association (TIA) as “Interim Standards” (IS)
2G air interface standards (PCS) include2G air interface standards (PCS) include
IS-54/136 – TDMA over 30 KHz channelsIS-54/136 – TDMA over 30 KHz channels
IS-95 – CDMA standard developed by Qualcomm in 1991 andIS-95 – CDMA standard developed by Qualcomm in 1991 and
adopted by TIA in 1993adopted by TIA in 1993
IS-634 standard for MSC-BSC interfaceIS-634 standard for MSC-BSC interface
IS-41 standard for MSC-MSC interfaceIS-41 standard for MSC-MSC interface
Services, interoperability, compatibility and performanceServices, interoperability, compatibility and performance
issues are addressed by TR-45/46 committeesissues are addressed by TR-45/46 committees
TR-45/46 reference model is similar to the GSMTR-45/46 reference model is similar to the GSM
architectural modelarchitectural model

 Properties of CDMA CellularProperties of CDMA Cellular
Frequency Diversity –Frequency Diversity – frequency-dependent transmissionfrequency-dependent transmission
impairments have less effect on wide-band signalimpairments have less effect on wide-band signal
Multipath ResistanceMultipath Resistance – can use RAKE receiver to coherently– can use RAKE receiver to coherently
combine multipath signalscombine multipath signals
PrivacyPrivacy – privacy is inherent since spread spectrum is obtained– privacy is inherent since spread spectrum is obtained
by use of noise-like signalsby use of noise-like signals
Graceful Degradation –Graceful Degradation – system only gradually degrades assystem only gradually degrades as
more users access the systemmore users access the system
Soft Handoff –Soft Handoff – mobile acquires new cell before disconnectingmobile acquires new cell before disconnecting
from the old; diversity combining of signals from the two cellsfrom the old; diversity combining of signals from the two cells
enhance performanceenhance performance
Near-far Problem –Near-far Problem – without power control, signals from MSwithout power control, signals from MS
closer to the BS will overwhelm signals from MS farther awaycloser to the BS will overwhelm signals from MS farther away

 Problems with CDMA CellularProblems with CDMA Cellular
 Self-Jamming –Self-Jamming – arriving transmissions from multiple users notarriving transmissions from multiple users not
aligned on chip boundaries unless users are perfectlyaligned on chip boundaries unless users are perfectly
synchronizedsynchronized
 Near-far Problem –Near-far Problem – signals closer to the receiver are receivedsignals closer to the receiver are received
with less attenuation than signals farther awaywith less attenuation than signals farther away
 Soft Handoff –Soft Handoff – requires that the mobile acquires the new cellrequires that the mobile acquires the new cell
before it relinquishes the old; this is more complex than hardbefore it relinquishes the old; this is more complex than hard
handoff used in FDMA and TDMA schemeshandoff used in FDMA and TDMA schemes

 1G and 2G – Voice Centric Systems1G and 2G – Voice Centric Systems
CellularCellular coveragecoverage is designed for voice serviceis designed for voice service
Area outage, e.g. < 10% or < 5%.Area outage, e.g. < 10% or < 5%.
Minimal, but equal, service everywhereMinimal, but equal, service everywhere
CellularCellular systemssystems are designed for voiceare designed for voice
20 ms framing structure20 ms framing structure
Strong FEC, interleaving and decoding delaysStrong FEC, interleaving and decoding delays
Spectral EfficiencySpectral Efficiency
around 0.04-0.07 bps/Hz/sectoraround 0.04-0.07 bps/Hz/sector
comparable for TDMA and CDMAcomparable for TDMA and CDMA

 3G Vision –Multimedia (Voice, Data, and Video)3G Vision –Multimedia (Voice, Data, and Video)
Universal global roamingUniversal global roaming
Multimedia (voice, data & video)Multimedia (voice, data & video)
Increased data ratesIncreased data rates
384 kbps while moving384 kbps while moving
2 Mbps when stationary at specific locations2 Mbps when stationary at specific locations
Increased capacity (more spectrally efficient)Increased capacity (more spectrally efficient)
IP architectureIP architecture
ProblemsProblems
No killer application for wireless data as yetNo killer application for wireless data as yet
Vendor-drivenVendor-driven

 Standardization BodiesStandardization Bodies
ITU (International Telecommunication Union)ITU (International Telecommunication Union)
Radio standards and spectrumRadio standards and spectrum
IMT-2000IMT-2000
ITU’s umbrella name for 3G which stands forITU’s umbrella name for 3G which stands for
International Mobile Telecommunications 2000International Mobile Telecommunications 2000
National and regional standards bodies areNational and regional standards bodies are
collaborating in 3G partnership projectscollaborating in 3G partnership projects
ARIB, TIA, TTA, TTC, CWTS. T1, ETSIARIB, TIA, TTA, TTC, CWTS. T1, ETSI
3G Partnership Projects (3GPP & 3GPP2)3G Partnership Projects (3GPP & 3GPP2)
Focused on evolution of access and core networksFocused on evolution of access and core networks

 IMT-2000 Vision-Integration of Services andIMT-2000 Vision-Integration of Services and
NetworksNetworks
Satellite
Macrocell
Microcell
Urban
In-Building
Picocell
Global
Suburban
Basic Terminal
PDA Terminal
Audio/Visual Terminal

 IMT-2000 Radio StandardsIMT-2000 Radio Standards
IMT-SC*IMT-SC* Single Carrier (UWC-136)Single Carrier (UWC-136): EDGE: EDGE
GSM evolution (TDMA); 200 KHz channels; sometimes calledGSM evolution (TDMA); 200 KHz channels; sometimes called
“2.75G”“2.75G”
IMT-MC*IMT-MC* Multi Carrier CDMA:Multi Carrier CDMA: CDMA2000CDMA2000
Evolution of IS-95 CDMA, i.e. cdmaOneEvolution of IS-95 CDMA, i.e. cdmaOne
IMT-DS*IMT-DS* Direct Spread CDMA:Direct Spread CDMA: W-CDMAW-CDMA
New from 3GPP; UTRAN FDDNew from 3GPP; UTRAN FDD
IMT-TC**IMT-TC** Time Code CDMATime Code CDMA
New from 3GPP; UTRAN TDDNew from 3GPP; UTRAN TDD
New from China;New from China; TD-SCDMATD-SCDMA
IMT-FT**IMT-FT** FDMA/TDMA (DECT legacy)FDMA/TDMA (DECT legacy)

 Cellular Network Evolution PathCellular Network Evolution Path
CDMA
GSM
TDMA
PHS
(IP-Based)
64 Kbps
GPRS
115 Kbps
CDMA 1xRTT
144 Kbps
EDGE
384 Kbps
cdma2000
1X-EV-DV
Over 2.4 Mbps
W-CDMA
(UMTS)
Up to 2 Mbps
2G
2.5G
2.75G 3G
1992 - 2000+
2001+
2003+
1G
1984 - 1996+
2003 - 2004+
TACS
NMT
AMPS
GSM/
GPRS
(Overlay)
115 Kbps
9.6 Kbps
9.6 Kbps
14.4 Kbps
/ 64 Kbps
9.6 Kbps
PDC
Analog Voice
Digital Voice
Packet Data
Intermediate
Multimedia
Multimedia
PHS
TD-SCDMA
2 Mbps?
9.6 Kbps
iDEN
(Overlay)
iDEN
Source: U.S. Bancorp Piper Jaffray

 Cellular Network Evolution Path-2Cellular Network Evolution Path-2
Broader Bandwidth Channels
with High Spectrum Efficiency
Advanced Network/Software
Architectures
Advanced Coding & Signal
Processing Techniques
Intelligent Antennas
Wideband Radios
Knowledge-Based
Network Operations
Unified Service
Networks
Digital Cellular
Technology
Microcellular &
Picocellular
Technologies
Wireless Intelligent
Network
Analog Cellular
Technology
Macrocellular
Technology
Integrated Voice/Data
& Wireless/Wireline
Multimedia Services
Location Services
Mobile Telephone
Service
Advanced Wireless
Voice Services
Wireless Data
Services
Tele-Presenting
Distance Learning
Intelligent Agent
Services
First Generation Second Generation Third Generation Fourth Generation
Mid-80s Mid-90s Year 2010 ?Year 2000+
W-CDMA
UWC-136
cdma2000
NMT
TACS
Analog AMPS
GSM
IS-54/ 136 TDMA
IS-95/ cdmaOne
PDC
DECT
?
Source: IEEE Communications Magazine

 High Speed Circuit Switched Data (HSCSD) forHigh Speed Circuit Switched Data (HSCSD) for
2.5G GSM2.5G GSM
Part of GSM Phase 2 developmentPart of GSM Phase 2 development
Use dedicated TDMA time slots for circuit switched dataUse dedicated TDMA time slots for circuit switched data
Each time slot yields a data rate of 14.4 KbpsEach time slot yields a data rate of 14.4 Kbps
Up to 4 time slots can be used for a data rate up to 57.6 KbpsUp to 4 time slots can be used for a data rate up to 57.6 Kbps
HSCSD connection using multiple time slots can be pre-empted byHSCSD connection using multiple time slots can be pre-empted by
voice calls to give up the extra slotsvoice calls to give up the extra slots
Suitable for streaming data applications such as digital audio/videoSuitable for streaming data applications such as digital audio/video
Inefficient for applications with bursty data traffic, such as WebInefficient for applications with bursty data traffic, such as Web
surfingsurfing
The service is not widely supportedThe service is not widely supported

 General Packet Radio Service (GPRS) for 2.5GGeneral Packet Radio Service (GPRS) for 2.5G
GSMGSM
Part of GSM Phase 2 developmentPart of GSM Phase 2 development
Also supported by IS-136 TDMA in N. AmericaAlso supported by IS-136 TDMA in N. America
Use shared TDMA time slots for packet switched dataUse shared TDMA time slots for packet switched data
MS uses a reservation MAC protocol to indicate needs for dataMS uses a reservation MAC protocol to indicate needs for data
bandwidth to BSC which schedules reserved time slots for the MSbandwidth to BSC which schedules reserved time slots for the MS
Up to 8 time slots can be used for a data rate up to 171.2 Kbps; inUp to 8 time slots can be used for a data rate up to 171.2 Kbps; in
practice MS’s are not assigned 8 time slotspractice MS’s are not assigned 8 time slots
GPRS using multiple time slots can be pre-empted by HSCSD or voiceGPRS using multiple time slots can be pre-empted by HSCSD or voice
calls to give up the extra slotscalls to give up the extra slots
Much more efficient for applications with bursty data traffic, such asMuch more efficient for applications with bursty data traffic, such as
Web surfingWeb surfing

 Enhanced Data rates for GSM Evolution (EDGE)Enhanced Data rates for GSM Evolution (EDGE)
for 2.5G GSMfor 2.5G GSM
Provides an evolution path from existing GSM/TDMA standards toProvides an evolution path from existing GSM/TDMA standards to
deliver 3G services in existing spectrum bandsdeliver 3G services in existing spectrum bands
Reuses GSM carrier bandwidth and time slot structureReuses GSM carrier bandwidth and time slot structure
Can be introduced in GSM using a minimum of only one time slotCan be introduced in GSM using a minimum of only one time slot
per BSper BS
Reuse of existing GSM and TDMA/IS-136 infrastructureReuse of existing GSM and TDMA/IS-136 infrastructure
Can be deployed using as little as 600 kHz of total bandwidthCan be deployed using as little as 600 kHz of total bandwidth
384 Kbps data capability to satisfy the IMT-2000 requirements for384 Kbps data capability to satisfy the IMT-2000 requirements for
pedestrian (microcell) and low speed vehicular (macrocell)pedestrian (microcell) and low speed vehicular (macrocell)
environmentsenvironments
144 Kbps data capability for high speed vehicular environment144 Kbps data capability for high speed vehicular environment

 3G WCDMA (UMTS) – Pros and Cons3G WCDMA (UMTS) – Pros and Cons
Wideband CDMAWideband CDMA
Standard for Universal Mobile Telephone ServiceStandard for Universal Mobile Telephone Service
(UMTS)(UMTS)
Committed standard for Europe and likelyCommitted standard for Europe and likely
migration path for other GSM operatorsmigration path for other GSM operators
Leverages GSM’s dominant positionLeverages GSM’s dominant position
Requires substantial new spectrumRequires substantial new spectrum
5 MHz each way (symmetric)5 MHz each way (symmetric)
Legally mandated in Europe and elsewhereLegally mandated in Europe and elsewhere
Sales of new spectrum completed in EuropeSales of new spectrum completed in Europe
At prices that now seem exorbitantAt prices that now seem exorbitant

 3G cdma20003G cdma2000
Specification developed by the Third Generation PartnershipSpecification developed by the Third Generation Partnership
Project 2 (3GPP2)Project 2 (3GPP2)
CDMA 2000 1xCDMA 2000 1x
currently deployed as 2.5G overlay on IS 95 systemscurrently deployed as 2.5G overlay on IS 95 systems
1.25 MHz channel bandwidth same as IS 951.25 MHz channel bandwidth same as IS 95
max data rate 144 Kbps now increasing to 307 Kbps in the futuremax data rate 144 Kbps now increasing to 307 Kbps in the future
CDMA 2000 1xEV (evolution using 1x channel bandwidth)CDMA 2000 1xEV (evolution using 1x channel bandwidth)
1xEV-DO data only, 384 Kbps - 2.4 Mbps max1xEV-DO data only, 384 Kbps - 2.4 Mbps max
1xEV-DV for data and voice, specified by 2003/4, up to 4.8 Mbps1xEV-DV for data and voice, specified by 2003/4, up to 4.8 Mbps
CDMA 2000 3x uses 3x1.25 MHz bandwidth, 2-4 MbpsCDMA 2000 3x uses 3x1.25 MHz bandwidth, 2-4 Mbps
CDMA 2000 1x EV-DO and CDMA 2000 3x are ITUCDMA 2000 1x EV-DO and CDMA 2000 3x are ITU
approved, IMT-2000 (3G) standardsapproved, IMT-2000 (3G) standards

 3G cdma2000 – Pros and Cons3G cdma2000 – Pros and Cons
Evolution from original Qualcomm CDMAEvolution from original Qualcomm CDMA
Now known as cdmaOne or IS-95Now known as cdmaOne or IS-95
Better migration story from 2G to 3GBetter migration story from 2G to 3G
cdmaOne operators don’t need additional spectrumcdmaOne operators don’t need additional spectrum
1xEVD0 promises higher data rates than UMTS, i.e. W-1xEVD0 promises higher data rates than UMTS, i.e. W-
CDMACDMA
Better spectral efficiency than W-CDMA(?)Better spectral efficiency than W-CDMA(?)
Arguable (and argued!)Arguable (and argued!)
CDMA2000 core network less matureCDMA2000 core network less mature
cmdaOne interfaces were vendor-specificcmdaOne interfaces were vendor-specific
Hopefully CDMA2000 vendors will comply w/ 3GPP2Hopefully CDMA2000 vendors will comply w/ 3GPP2

 3G TD-SCDMA (Time-Division, Synchronous3G TD-SCDMA (Time-Division, Synchronous
CDMA)CDMA)
Time division duplex (TDD)Time division duplex (TDD)
Chinese developmentChinese development
Will be deployed in ChinaWill be deployed in China
Good match for asymmetrical traffic!Good match for asymmetrical traffic!
Single spectral band (1.6 MHz) possibleSingle spectral band (1.6 MHz) possible
Costs relatively lowCosts relatively low
Handset smaller and may cost lessHandset smaller and may cost less
Power consumption lowerPower consumption lower
TDD has the highest spectrum efficiencyTDD has the highest spectrum efficiency
Power amplifiers must be very linearPower amplifiers must be very linear
Relatively hard to meet specificationsRelatively hard to meet specifications

 Major 3G Standardization Bodies and ForumsMajor 3G Standardization Bodies and Forums
Standard Organization Region
International Telecommunications
Union (ITU)
International
European Telecommunications
Standard Institute (ETSI)
Europe
Telecommunications Industry
Association (TIA)
North America
Association of Radio Industries and
Business (ARIB)
Japan
American National Standard Institute
(committee T1P1)
North America

 Major 3G Standardization Bodies and Forums-Major 3G Standardization Bodies and Forums-Cont’dCont’d
33rdrd
Generation Partnership Project (3GPP)Generation Partnership Project (3GPP)
Focus on setting global standard for UMTS Terrestrial RadioFocus on setting global standard for UMTS Terrestrial Radio
Access (UTRA)Access (UTRA)
Involve ETSI (Europe), ARIB (Japan), T1P1 (USA), etc.Involve ETSI (Europe), ARIB (Japan), T1P1 (USA), etc.
33rdrd
Generation Partnership Project 2 (3GPP2)Generation Partnership Project 2 (3GPP2)
Focus on setting global standard for cdma2000Focus on setting global standard for cdma2000
More of a N. American focusMore of a N. American focus

 UTRA ParametersUTRA Parameters
UTRA FDDUTRA FDD UTRA TDDUTRA TDD
Official nameOfficial name IMT-DSIMT-DS IMT-TCIMT-TC
Uplink frequencyUplink frequency 1920 - 1980 MHz1920 - 1980 MHz 2010 - 2025 MHz2010 - 2025 MHz
Downlink frequencyDownlink frequency 2110 - 2170 MHz2110 - 2170 MHz 2010 - 2025 MHz2010 - 2025 MHz
Carrier spacingCarrier spacing 5 MHz5 MHz 5 MHz5 MHz
Duplex schemeDuplex scheme FDDFDD TDDTDD
Chip rateChip rate 3.84 Mcps3.84 Mcps 3.84 Mcps3.84 Mcps
ModulationModulation QPSKQPSK QPSKQPSK
Frame lengthFrame length 10 ms10 ms 10 ms10 ms
Time slots/frameTime slots/frame N/AN/A 1515

 Mobile Wireless SpectrumMobile Wireless Spectrum
Bands Frequencies GSM/
(MHz) (MHz) Regions EDGE WCDMA CDMA2000
450 450-467 Europe x x
480 478-496 Europe x
800 824-894 America x x
900 880-960 Europe/APAC x x
1500 Japan PDC x
1700 1750-1870 Korea x
1800 1710-1880 Europe/APAC x x x
1900 1850-1990 America x x x
2100
1885-2025 &
2100-2200
Europe/APAC x x
2500 2500-2690 ITU Proposal x

 Prospectus for Global RoamingProspectus for Global Roaming
Multiple vocoders (AMR, EVRC, SMV,…)Multiple vocoders (AMR, EVRC, SMV,…)
Six or more spectral bandsSix or more spectral bands
800, 900, 1800, 1900, 2100, 2500, …? MHz800, 900, 1800, 1900, 2100, 2500, …? MHz
At least four modulation variantsAt least four modulation variants
GSM (TDMA), W-CDMA, CDMA2000, TD-SCMDAGSM (TDMA), W-CDMA, CDMA2000, TD-SCMDA
The handset approachThe handset approach
Advanced siliconAdvanced silicon
Software defined radioSoftware defined radio
Improved batteriesImproved batteries

 Biggest Threats to Today’s 3G-Wireless LANsBiggest Threats to Today’s 3G-Wireless LANs
Faster than 3GFaster than 3G
11 or 56 Mbps vs. <2 Mbps for 3G when stationary11 or 56 Mbps vs. <2 Mbps for 3G when stationary
Data experience matches the InternetData experience matches the Internet
With the added convenience of mobileWith the added convenience of mobile
Same user interface (doesn’t rely on small screens)Same user interface (doesn’t rely on small screens)
Same programs, files, applications, Websites.Same programs, files, applications, Websites.
Low cost, low barriers to entryLow cost, low barriers to entry
Organizations can build own networksOrganizations can build own networks
Like the Internet, will grow virallyLike the Internet, will grow virally
Opportunity for entrepreneurs!Opportunity for entrepreneurs!
Opportunity for wireless operators?Opportunity for wireless operators?

 Wireless Local Area Networks (WLANs)Wireless Local Area Networks (WLANs)

 Wireless LAN StandardsWireless LAN Standards

 BluetoothBluetooth

 Ultra-Wideband Radio (UWB)Ultra-Wideband Radio (UWB)

 Why UWB is more Interesting?Why UWB is more Interesting?

 IEEE 820.15.4 (ZigBee Radios)IEEE 820.15.4 (ZigBee Radios)

 WLANs Data RatesWLANs Data Rates

 WLANs RangeWLANs Range

 WLANs Power DissipationWLANs Power Dissipation

 Technology TrendsTechnology Trends
Improvements in system capacity through advanced signaling,Improvements in system capacity through advanced signaling,
detection and signal processing techniques:detection and signal processing techniques:
Orthogonal frequency division multiplexing OFDMOrthogonal frequency division multiplexing OFDM
Turbo codingTurbo coding
Multiple-user detection (interference cancellation)Multiple-user detection (interference cancellation)
Multiple-input multiple-output (MIMO) processingMultiple-input multiple-output (MIMO) processing
Software radioSoftware radio
Improvements in features and capabilities for better services:Improvements in features and capabilities for better services:
Full integration into the Internet for multimedia servicesFull integration into the Internet for multimedia services
Seamless roaming between cellular, wireless LAN, and satelliteSeamless roaming between cellular, wireless LAN, and satellite
networksnetworks

 Beyond 3G?Beyond 3G?
 Need to provide: “beyond data”Need to provide: “beyond data”
Higher data rates (at least on downlink)Higher data rates (at least on downlink)
More multimedia contentsMore multimedia contents
Voice, data, video, WWW access.Voice, data, video, WWW access.
broadcastbroadcast as well asas well as cellularcellular
Wideband (10 MHz or more)Wideband (10 MHz or more)
 Main CandidatesMain Candidates
WOFDMWOFDM
WCDMAWCDMA
Multi-Carrier CDMAMulti-Carrier CDMA
Other???Other???
 How will these systems access the Internet andHow will these systems access the Internet and
coexist with wireless LANs?coexist with wireless LANs?

 In Short …In Short …
Wireless data and multimedia are the main driversWireless data and multimedia are the main drivers
for future generations of cellular systemsfor future generations of cellular systems
Several competing standards (as in 2G)Several competing standards (as in 2G)
Evolutionary path unclearEvolutionary path unclear
Killer application unknownKiller application unknown
What do mobile users want?What do mobile users want?
Will wireless LANs or cellular systems dominate theWill wireless LANs or cellular systems dominate the
future wireless data landscape?future wireless data landscape?

-introduction-to-cellular-mobile-communications

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