Course 131 Introduction to CDMAScott Baxterwww.howcdmaworks.com 800-890-0829

CDMA 131 Outline DeploymentN Multiple

Overview and Outlook CDMA BasicsAccess Technology Survey N CDMA coding principles N Spread Spectrum principles N Forward and Reverse Channel Structure CDMA CDMA

System ArchitectureCBSC BTS OMC-R

N PCSC N Power

Details and Operation

Control N Handoff mechanics N Optimization concepts2

CDMA Deployment Status Review

80 70 60 50 Millions 40 30 20 10 0

CDMA Worldwide Subscriber Growth1Q-2000 SUBSCRIBERS 57M

19 M

32 M

6.5 M1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 2000 1997 1998 1999

Source: www.cdg.org

IS-95/J-Std008 CDMA commercial deployment began in AsiaN

Hong Kong, South Korea

North America started later but is rapidly growing, both at 800 MHz and 1900 MHz. South/Central America is just beginning widespread commercial deployment 4

United States PCS Auction WinnersSprint PCS CDMAThe Largest Players, Areas, and Technologies Sprint PCSN N N

AT&T Wireless IS-136

N

Partnership of Sprint, TCI, Cox Cable Bid & won in 2/3 of US markets A or B blocks Sprint itself has D and/or E blocks in remaining markets Technology: CDMA Bid & won a majority of markets in A&B Blocks will combine and integrate service between its new PCS 1900 systems and its former McCaw cellular 800 MHz. properties Technology: TDMA IS-54, IS-136B Partnership of Airtouch, US West, Bell Atlantic, Technology: CDMA Western Wireless, OmniPoint, BellSouth, GTE, Powertel, Pacific Bell Technology: TDMA (ETSI GSM)5

AT&T Wireless SystemsN N

Primeco CDMAWestern Wireless Pacific Bell Aerial OmniPoint BellSouth Powertel

N

PrimecoN N

GSM

GSM OperatorsN N

Canadian Wireless Technologies, Manufacturers, and OperatorsFrequency Band, MHz 900 1900 1900 1900 800 B 1900 800 A Technology Network Manufacturer Motorola Lucent Ericsson Nortel Nortel ? Ericsson

Geographic AreaBritish Alberta Columbia SaskatchNew Manitoba Ontario Quebec ewan Brunswick Nova Scotia Newfoundland

IDEN CDMA GSM CDMA AMPS TDMA IS-136 AMPS TDMA

Clearnet MIKE

Clearnet PCS Microcell FIDOMobilink Canada?

Rogers Cantel

6

3G Wideband CDMA

Regardless of the degree of acceptance of IS-95 narrowband CDMA systems, Third Generation proposals for wideband CDMA are attracting great attention both from manufacturers and carriers 3G systems will offer higher bandwidth services, including medium speed data service at rates up to 384 Kbs for mobile users, and up to 2 MBs for stationary users Operators and manufacturers are presently waiting and studying the limited number of trials of 3G systems presently underway7

2G to 3G Migration Paths2G System CDMA GSMTechnology Family cdma20003G Mode MulticarrierFrequency Division Duplex Time Division Duplex

WCDMA

GPRSTDMAUWC-136

EDGE and 136 HS outdoor

136 HS indoor8

North American 3G Migration Plans800 MHz.. Vodaphone/Airtouch 9,000,000 Verizon/BAMS/GTE 12,800,000 Alltel 5,060,000Other CDMA 2,059,000

1900 MHz.. Sprint PCS 7,400,000 Verizon 2,000,000

1xRTT cdma2000 3xRTT HDR

?

VoiceStream 3,100,000 PacBell Wireless 2,000,000 Powertel & Others 1,000,000

AT&T Wireless 10,800,000

?

AT&T Wireless 1,900,000

WCDMA UMTS UTRA

Cingular/SBC/BellSouth 13,090,000Other TDMA 4,823,000

?Other TDMA 724,000

?Nextel 5,721,000

?

X?

EDGE9

??!

Next Generation CDMA Enhancements

IS-95BN N N

Improved handoff, faster data, improved access 2x capacity in same chip rate & bandwidth All IS-95B refinements Up to 2.4 Mb/s on a single CDMA signal US (CDMA2000) version: 3x chip rate and more Even faster data: 2 MB bursting European (W-CDMA) version: GPS not required The European equivalent to 3xRTT CDMA 3G migration path for todays GSM systems10

1xRTT (2.5G) Qualcomms HDR (High Data Rates)N

3xRTTN N

UMTS Universal Mobile Terrestrial ServicesN N

Capacity of CDMA Networks

Wireless System CapacityEach wireless technology (AMPS, NAMPS, D-AMPS, GSM, CDMA) uses a specific modulation type with its own unique signal characteristics

AMPS, D-AMPS, N-AMPS1 3 1 Users 2 3 7 1 6 4 5

Signal Bandwidth determines how many RF signals will fit in the operators licensed spectrumRobustness of RF signal determines tolerable level of interference and necessary physical separation of cochannel cells

30

30

Vulnerability: C/I 17 dB 10 kHz Bandwidth Typical Frequency Reuse N=7

8

Users

Vulnerability: C/I 6.5-9 dB

1 4

2 3

Number of users per RF signal directly affects capacity In the following page, we will develop the number of users and traffic in erlangs per site for each of the popular wireless technologies

200 kHz

Typical Frequency Reuse N=4 Vulnerability: EbNo 6 dB

CDMA 22 Users1250 kHz

1 1 1 1 1 1 1

1 1 1

1 1

1 1

Typical Frequency Reuse N=1

12

Wireless System Capacity Comparisons800 Cellular (A,B) Fwd/Rev Spectrum kHz. 12,500 12,500 12,500 Technology AMPS TDMA CDMA Req'd C/I or Eb/No, db 17 17 6 Freq Reuse Factor, N 7 7 1 RF Signal BW, kHz 30 30 1250 Total # RF Carriers 416 416 9 RF Sigs. per cell @N 59 59 9 # Sectors per cell 3 3 3 #CCH per sector 1 1 0 RF Signals per sector 18 18 9 Voicepaths/RF signal 1 3 22 SH average links used 1.66 Unique Voicepaths/carrier 13.253 Voicepaths/Sector 18 54 198 Unique Voicepaths/Sector 18 54 119 P.02 Erlangs per sector 11.5 44 105.5 P.02 Erlangs per site 34.5 132 316.5 Capacity vs. AMPS800 1 3.8 9.2 1900 PCS (A, B, C) 1900 PCS (D, 15,000 15,000 15,000 5,000 5,000 TDMA GSM CDMA TDMA GSM 17 12 6 17 12 7 4 1 7 4 30 200 1250 30 200 500 75 11 166 25 71 18 11 23 6 3 3 3 3 3 1 0 0 1 0 22 6 11 6 2 3 8 22 3 8 1.66 13.253 66 48 242 18 16 66 48 145 18 16 55.3 38.4 130.9 11.5 9.83 165.9 115.2 392.7 34.5 29.49 4.8 3.3 11.4 1.0 0.9 E, F) 5,000 CDMA 6 1 1250 3 3 3 0 3 22 1.66 13.253 66 39 30.1 90.3 2.6

13

Multicarrier CDMA CapacityCDMA Carrier Frequencies 1 2 3 4 5 6 7 8 9 1011

fFwd/Rev Spectrum kHz. 12,500 1,800 3,050 4,300 5,550 6,800 8,050 9,300 10,550 Technology AMPS CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA Req'd C/I or Eb/No, db 17 6 6 6 6 6 6 6 6 Freq Reuse Factor, N 7 1 1 1 1 1 1 1 1 RF Signal BW, kHz 30 1250 1250 1250 1250 1250 1250 1250 1250 Total # RF Carriers 416 1 2 3 4 5 6 7 8 RF Sigs. per cell @N 59 1 2 3 4 5 6 7 8 # Sectors per cell 3 3 3 3 3 3 3 3 3 #CCH per sector 1 0 0 0 0 0 0 0 0 RF Signals per sector 18 1 2 3 4 5 6 7 8 Voicepaths/RF signal 1 22 22 22 22 22 22 22 22 SH average links used 1 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66 Unique Voicepaths/carrier 1 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 Voicepaths/Sector 18 22 44 66 88 110 132 154 176 Unique Voicepaths/Sector 18 13 26 39 53 66 79 92 106 P.02 Erlangs per sector 11.5 7.4 18.4 30.1 43.1 55.3 67.7 80.2 93.8 P.02 Erlangs per site 34.5 22.2 55.2 90.3 129.3 165.9 203.1 240.6 281.4 Capacity vs. AMPS800 1 0.64 1.60 2.6 3.7 4.8 5.9 7.0 8.2 11,800 CDMA 6 1 1250 9 9 3 0 9 22 1.66 13.3 198 119 105.5 316.5 9.2 13,050 CDMA 6 1 1250 10 10 3 0 10 22 1.66 13.3 220 132 119.1 357.3 10.4 14,300 CDMA 6 1 1250 11 11 3 0 11 22 1.66 13.3 242 145 130.9 392.7 11.4

14

Current CDMA Network Capacity Issues

Today, CDMA networks for the most part are still single-carrierN N

this severely limits the capacity of one BTS to approximately 20 erlangs implementing additional carriers brings logistical problems involving handoffs and system acquisition by mobiles

Multiple-carrier operation is essential to achieve reasonable capacities Within networks, there are strategies for squeezing the most out of overloaded single-carrier BTSs. Some of the main points are:N N

reduce Pilot, Sync, and Paging levels as low as possible, thereby gaining precious additional energy for traffic channels reduce BTS traffic channel DGU settings as low as possible without provoking forward link FER.

15

CDMA Basics

Multiple Access Technologies

FDMAPower

FDMA (example: AMPS)Frequency Division Multiple Access N each user has a private frequency

Tim

e

Fr

e

e qu

nc

y

TDMAPowerTim

TDMA (examples: IS-54/136, GSM)Time Division Multiple Access N each user has a private time on a private frequency

e

Fre

q

n ue

cy

CDMA (IS-95, J-Std. 008)Code Division Multiple Access N users co-mingle in time and frequency but each user has a private code

CDMAPowerTim

e

Fr

eq

n ue

cy

17

Other Technologies: Avoiding Interference AMPS,

TDMA and GSM depend on physical distance separation to keep interference at low levels Co-channel users are kept at a safe distance by careful frequency planning Nearby users and cells must use different frequencies to avoid interference

AMPS-TDMA-GSM1 4 7 6 1 4 2 3 6 1 5 1 7 3 5 1 4 2 3 6 5 1 2 7 1

(carrier/interference ratio)

Figure of Merit: C/I

AMPS: +17 dB TDMA: +14 to 17 dB GSM: +7 to 9 dB.18

CDMA: Using A New Dimension All

CDMA users occupy the same frequency at the same time! Time and frequency are not used as discriminators CDMA interference comes mainly from nearby users CDMA operates by using CODING to discriminate between users Each user is a small voice in a roaring crowd -- but with a uniquely recoverable code

CDMA

AMPS: +17 dB TDMA: +14 to +17 dB GSM: +7 to 9 dB. CDMA: -10 to -17 dB. CDMA: Eb/No ~+6 dB.19

(carrier/interference ratio)

Figure of Merit: C/I

CDMA Uses Code ChannelsA

CDMA signal uses many chips to convey just one bit of information Each user has a unique chip pattern, in effect a code channel To recover a bit, integrate a large number of chips interpreted by the users known code pattern Other users code patterns appear random and integrate toward low values, hence dont disturb the bit decoding decision

Building a CDMA Signalfrom Users VocoderForward Error Correction

Bits

SymbolsCoding and Spreading

Chips

20

CDMA is a Spread-Spectrum System TraditionalTRADITIONAL COMMUNICATIONS SYSTEM Spread Spectrum NarrowbandSlow Information Sent TX Signal RX Slow Information Recovered

technologies try to squeeze signal into minimum required bandwidth CDMA uses larger bandwidth but uses resulting processing gain to increase capacity

SPREAD-SPECTRUM SYSTEMWideband Signal

Slow Information Sent TX Fast Spreading Sequence

Slow Information Recovered RX

Fast Spreading Sequence

Spread Spectrum Payoff:Processing Gain

21

Spreading: What we do, we can undoORIGINATING SITESpread Data Stream Input Data Recovered Data

DESTINATION

Spreading Sequence

Spreading Sequence

Sender

combines data with a fast spreading sequence, transmits spread data stream Receiver intercepts the stream, uses same spreading sequence to extract original data22

Shipping and Receiving via CDMAShippingData

Receiving FedEx FedExData

Mailer

Mailer

Whether

in shipping and receiving, or in CDMA, packaging is extremely important! Cargo is placed inside nested containers for protection and to allow addressing The shipper packs in a certain order, and the receiver unpacks in the reverse order CDMA containers are spreading codes23

CDMAs Nested Spreading SequencesORIGINATING SITEX+A Spread-Spectrum Chip Streams X+A+B X+A+B+C X+A+B

DESTINATIONX+A

Input Data

X

Recovered Data

X

Spreading Spreading Spreading Sequence Sequence Sequence

A

B

C

Spreading Spreading Spreading Sequence Sequence Sequence

C

B

A

CDMA

combines three different spreading sequences to create unique, robust channels The sequences are easy to generate on both sending and receiving ends of each link What we do, we can undo 24

The Three CDMA Spreading Sequences WalshN 64

Codes: 64 are available

chips long -- lasts 1/19200 sec N mutually orthogonal PN

Short Code: one pair is used (I & Q)

N 32K

long -- lasts 26-2/3 mS, repeats 75x in 2 sec. generated in 15-bit tapped shift register N Nearly self-orthogonal if compared out-of-sync PN

Long Code: only one is used

N 242-1

chips long -- lasts 40+ days! generated in 42-bit tapped shift register N Any short sample is nearly orthogonal with any other short sample25

Code Channels in the Forward DirectionMTX BSCPilot Sync Paging Vocoder Vocoder Vocoder Vocoder more more

BTS (1 sector)Walsh #0 FEC Walsh #32 FEC Walsh #1 FEC Walsh #12 FEC Walsh #23 FEC Walsh #27 FEC Walsh #44 FEC more

Short PN Code PN Offset 246 I Q Transmitter, Sector X

A Forward Channel is identified by: its CDMA RF carrier Frequency the unique Short Code PN Offset of the sector the unique Walsh Code of the user26

Code Channels in the Reverse DirectionMTX BSC BTS (1 sector)Long Code Gen Access Channels Channel Element Long Code Gen Vocoder Channel Element Long Code Gen Vocoder Channel Element Long Code Gen Vocoder Channel Element Long Code Gen Vocoder more more Channel Element more27

A Reverse Channel is identified by: its CDMA RF carrier Frequency the unique Long Code PN Offset of the individual handsetLong Code Receiver, Sector X Long Code

Long Code

Long Code

Long Code Long Code

CDMA Network Architecturewww.motorola.com

Structure of a Typical Wireless SystemHLRHLR Home Location Register (subscriber database)

SUPPORT FUNCTIONS

SWITCH Voice Mail System

BASE STATION CONTROLLER

BASE STATIONS

PSTN Local Carriers Long Distance Carriers

Mobile Telephone Switching OfficeATM Link to other CDMA Networks (Future)

29

Motorola CDMA System ArchitectureOMC-R PCSCOMC-R Processor Application Processor (or SC-UNO)

BTS (SC614T/611)Motorola Advanced Wideband Interface (MAWI)

Personal Communications Switching Center

CBSCDSC EMX-2500 or EMX-5000 Mobility Manager

BTS (SC9600/4800/2400) Group Line Interface (GLI) Multichannel CDMA Card (MCC)Local Maintenance Facility

PSTN

Transcoder

PC

30

The Motorola PCSC PersonalEMX-2500

Communications Switching Center Primary functionsN Call

EMX-5000 DSC EMX-2500 or EMX-5000

PSTN

Processing N HLR-VLR access N Intersystem call delivery (IS41C) N Billing Data Capture N Calling Features & Services31

The Motorola CBSC

Centralized Base Station Controller Mobility ManagerN N N

allocation of BTS resources handoff management Call management & supervision vocoding soft handoff management FER-based power control routing of all traffic and control packets32

TranscoderN N N N

CBSCMobility Manager

Transcoder

The Motorola BTS FamilyBTS (SC614T/611)Motorola Advanced Wideband Interface (MAWI)

Primary function: Air linkN

N N

generate, radiate, receive CDMA RF signal IS-95/J.Std. 8 high-efficiency T1 backhaul test capabilities

SC611 Microcell

BTS (SC9600/4800/2400) Group Line Interface (GLI) Multichannel CDMA Card (MCC)Local Maintenance Facility

PC

SC614T

SC4852 33

CDMA Details and Operation

Variable Rate Vocoding & MultiplexingDSP QCELP VOCODER

Vocoders

compress speech, reduce bit rate CDMA uses a superior Variable Rate VocoderN full

20ms Sample Pitch Filter Codebook Coded Result Feedback Formant Filter

rate during speech N low rates in speech pauses N increased capacity N more natural sound Voice,

bits 288

Frame Sizes Full Rate Frame

144 1/2 Rate Frame 72 1/4 Rt. 36 1/8

signaling, and user secondary data may be mixed in CDMA frames

Frame Contents: can be a mixture of Voice Signaling Secondary

35

Forward Power ControlBSC BTS (1 sector)Pilot Sync Paging User 1 Vocoder/ Selector User 2 User 3 more Transmitter, Sector X I Q Short PN

Help!Forward RF

The

BTS continually reduces the strength of each users forward baseband chip stream When a particular handset sees errors on the forward link, it requests more energy The complainers chip stream gets a quick boost; afterward, continues to diminish 36

Reverse Power Control800 bits per second

BSCBad FER? Raise Setpoint

BTSStronger than setpoint? Setpoint

Reverse RF

RX RF Digital Open Loop Closed Loop

TX RF Digital

Three

methods work in tandem to equalize all handset signal levels at the BTSN Reverse

Occasionally, as needed

Handset

Open Loop: handset adjusts power up or down based on received BTS signal (AGC) N Reverse Closed Loop: Is handset too strong? BTS tells up or down 1 db 800 times/second N Reverse Outer Loop: BSC has FER trouble hearing handset? BSC adjusts BTS setpoint37

Whats In a Handset?Digital Rake Receiver Symbols Chips Traffic CorrelatorPN xxx Walsh xx Walsh xx Walsh xx Messages

Receiver RF Section IF, DetectorAGC RF Duplexer RF Open Loop

Symbols

Traffic CorrelatorPN xxx PN xxx

CPU

Viterbi Decoder Packets Audio Vocoder Audio Messages

Traffic Correlator

Pilot SearcherPN xxx Walsh 0

Transmit Gain Adjust

Transmitter RF Section

Transmitter Digital SectionLong Code Gen.

38

The Rake ReceiverHandsetRFBTS BTS

Rake Receiver PN Walsh PN PN Walsh Walsh

Voice, Data, Messages Pilot Ec/Io

Searcher PN W=0

Every

frame, handset uses combined outputs of the three traffic correlators (rake fingers) Each finger can independently recover a particular PN offset and Walsh code Fingers can be targeted on delayed multipath reflections, or even on different BTSs Searcher continuously checks pilots39

CDMA Soft Handoff MechanicsMTX BSCSel.BTS BTS

Handset RF

Rake Receiver PN Walsh PN PN Walsh Walsh

Voice, Data, Messages Pilot Ec/Io

Searcher PN W=0

CDMA

soft handoff is driven by the handset

N Handset

continuously checks available pilots N Handset tells system pilots it currently sees N System assigns sectors (up to 6 max.), tells handset N Handset assigns its fingers accordingly N All messages sent by dim-and-burst, no muting! Each

end of the link chooses what works best, on a frame-by-frame basis!N Users

are totally unaware of handoff

40

Softer HandoffMTX BSCSel.BTS

Handset RF

Rake Receiver PN Walsh PN PN Walsh Walsh

Voice, Data, Messages Pilot Ec/Io

Searcher PN W=0

Each

BTS sector has unique PN offset & pilot Handset will ask for whatever pilots it wants If multiple sectors of one BTS simultaneously serve a handset, this is called Softer Handoff Handset is unaware, but softer handoff occurs in BTS in a single channel element Handset can even use combination soft-softer handoff on multiple BTS & sectors41

Pilot Sets and Soft Handoff Parameters Handset

views pilots in sets Handset sends message to system whenever:N It

notices a pilot in neighbor or remaining set exceeds T_ADD N An active set pilot drops below T_DROP for T_TDROP time N A candidate pilot exceeds an active by T_COMP Handoff

PILOT SETS Active 6 Candidate 5 Neighbor 20 Remaining HANDOFF PARAMETERST_ADD T_TDROP

setup processing time usually