cdma basics

CDMA

WELCOME TO CDMA OVERVEIW INTRODUCTION TO CDMA RADIO INTERFACE

SECTION 1CODE DIVISION MULTIPLE ACCESS

Section Introduction

•The CDMA frequency band•Frequency Allocation in CDMA•Understanding the DSSS•Codes and their functions in CDMA•Generation of Codes•Spreading And Despreading with Codes

SECTION 2HOW CDMA WORKS

LET US PUT EVERYTHING TOGETHER


•Forward link Architecture•Reverse Link Architecture•Logical Channels on Forward Link•Logical Channels on Reverse Link

SECTION 3CALL PROCESSING IN CDMA


•Mobile Initialization•Mobile Registration•Handoff Types•Rake Receiver•Power Control•Vocoding

SECTION 4INTRODUCTION TO DATA IN CDMA

Section Introduction•DATA Layers•Data and Quality•FCH and SCH •Dormant Mode•MAC and RLP•SARA

SECTION 5

INTRODUCTION TO LUCENT BSS


•Lucent Cellular Network Architecture•Application Processors•OMP-Fx•Modcell Components (3.0& 4.0)

“Hello”

“Shalom” “Guten Tag”

⇔

“Time division”“Frequency division!”

“CHAOS”

“Buenos Dias”“Bonjour”

The SYMPHONY!

GSM Vs CDMA

FREQUENCY REUSE IN CDMA & TDMA

TYPICAL TDMA SYSTEMEACH CELL USES DIFFERENT FREQUENCY

THE PATTERN IS REPEATED FOR THE NEXT SET OF CELL SITES

TYPICAL CDMA SYSTEMEACH CELL USES SAME FREQUENCY

F 1 F 1

F 1

F 1

F 1

F 1

F 1

F 1

F 2

F 5

F 4F 6

F 7 F 3

7 cell re-use pattern

f7

f7

f2

f2

f6

f6

f1

f5f3

f4

f1

f5f3

f4

Frequency Reuse

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1

f1

FREQUENCY REUSE IN in CDMA

f1f1

User 1User 2User 3User 4

User n

Code 1Code 2Code 3Code 4

Code n

1800 MHz 1850 MHz 1910 MHz 1930 MHz 1990 MHz 2000 MHz

Mobile Tx Cell Tx

In GSM small time slots of the spectrum (200 kHz) are used by different users as channels.

Spread spectrum uses much larger slice (1.25 MHz) of the available bandwidth.Same slice is used for all user with no time multiplexing but each user is assigns with a different code to uniquely identify them.

Spread Spectrum Concept

CDMA Cellular Spectrum

846.5MHz

825MHz

824MHz

835MHz

845MHz

849MHz

A’’ A A’B B’ Reverse link

891.5MHz

870MHz

869MHz

880MHz

890MHz

894MHz

A’’ A A’B B’ Forward link

2 - 7

850 (Cellular) CDMA Channel Frequencies

BandChannel Number

Sub-Block

Modular Cell Transmit/Mobile Receive Frequencies

Modular Cell Receive/Mobile Transmit Frequencies

850 TX (MHz) 850 RX (MHz)

A’’ 1019 A” 869.88 824.88

37 A3 871.11 826.11

78 872.34 827.34

119 A2 873.57 828.57160 874.80 829.80201 876.03 831.02242 A1 877.26 832.26283

878.49 833.49(Primary)

A

890.73 845.73691 A’(Secondary)

A’

384 881.52 836.52(Primary) B1 882.75 837.75

425883.98 838.98466

885.21 846.21507B2548

B

589

630

886.44 841.44

887.67 842.67

B3 888.90 843.90

777 B’ 893.31 848.31B’(Secondary)

DIRECT SEQUENCE SPREAD SPECTRUM

A System is said to be using DSSS if it follows the two basic rules mentioned

•The Bandwidth of the Carrier frequency must be much larger than the Bandwidth of the baseband Signals to be transmitted. •The same codes that are used for coding the signal must also be used for decoding the signals.

PROCESSING GAIN

The Processing Gain and Capacity Relation

# USERS PROCESING GAIN (dB)

1 21 dB

2 18 dB

3 15 dB

8 12 dB

16 9 dB

32 6 dB

CDMA Spreading GainConsider a user with a 9600

bps Vocoder talking on a CDMA signal 1,228,800 Hz wide.

The processing gain is 1228800/9600=128,

which is 21 db.What happens if additional

users are added?

S/N = G/N

2 Users S/N = ___1___ = 128

3 Users S/N = ___1___ = 64

5 Users S/N = ____1___ = 32

1/128

2/128

4/128

9 Users S/N = ___1___ = 16

17 Users S/N = ____1____ = 8

8/128

16/128

Capacity Quality Related

CDMA’s Nested Spreading Sequences

“Shipping and Receiving” via CDMA

U1 = 0110010101001000

C1 ( 100110….10110010)*

=U1C1 ( 100110………………………0000)

U1C1 ( 100110………………………00000)

U1 = 0110010101001000

C1 ( 100110….10110010)*

=

UnCn

U4C4

U3C3

U2C2

UnCn*C1 = 0, UnCn*Cn = Un

U4C4*C1 = 0, U4C4*C4 = U4

U3C3*C1 = 0, U3C3*C3 = U3

U2C2*C1 = 0, U2*C2*C2 = U2

C1*C1 = 1, C2*C2 = 1…. Cn*Cn = 1 BUT C1*C2 = 0…C1*Cn = 0

DSSS Spreading /Despreading

The Three CDMA Spreading Techniques

Orthogonal Sequences

• Definition:Orthogonal functions have zero correlation. Two binary sequences are orthogonal if the process of “XORing” them results in an equal number of 1’s and 0’s. Example:Example:

00000000((XOR) 01010101

------------01010101

• Generation Sequence:Generation Sequence:

- Seed0 0

0 1- Repeat: right & below

- Invert: diagonally

0 0

0 1

0 0

0 1

0 0

0 1

1 1

1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 00 1 0 10 0 1 10 1 1 0

0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 6 6 6 60 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 30 0

0 0 0 0 0 0 0

0 0 1 1 1

1 1 1 1 1 1 2

2 2 2 2 2 2 2

2 2 3 3 …

……

6 6

6 60 1

2 3 4 5 6 7 8

9 0 1 2 3 4 5

6 7 8 9 0

1 2 3 4 5 6 7

8 9 0 1 …

…... 0 1 2 3

Walsh Codes

ORTHOGONALITY OF WALSH CODES

Orthogonal Spreading

11

01100110100110011001100101100110100110010110011001100110100110010110011010011001100110010110011010011001011001100110011010011001

10011001011001100110011010011001011001101001100110011001011001101001100101100110011001101001100101100110100110011001100101100110

Walsh Function #59Walsh Function #59

Pattern to be TransmittedPattern to be Transmitted

Orthogonal Spreading

00

0 1 1 0 0 1 1 0

00

0 1 1 0 0 1 1 0

11

0 1 1 0 0 1 1 0

11

0 1 1 0 0 1 1 0

11

0 1 1 0 0 1 1 0

1 0 0 11 0 0 1 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 0 11 0 0 1 1 0 0 1 1 0 0 1

+1+1

-1-1

+1+1

-1-1

User DataUser Data

OrthogonalOrthogonalSequenceSequence

Tx DataTx Data

Decoding Using a Correct Code

00

0 1 1 0 0 1 1 0

00

0 1 1 0 0 1 1 0

11

0 1 1 0 0 1 1 0

11

0 1 1 0 0 1 1 0

11

0 1 1 0 0 1 1 0

1 0 0 11 0 0 1 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 0 11 0 0 1 1 0 0 1 1 0 0 1

+1+1

-1-1

CorrectCorrectFunctionFunction

Rx DataRx Data

0 0 0 00 0 0 0 0 0 0 00 0 0 0 1 1 1 11 1 1 1 1 1 1 11 1 1 11 1 1 11 1 1 1

??

0 1 0 10 1 0 1

??

0 1 0 10 1 0 1

??

0 1 0 10 1 0 1

??

0 1 0 10 1 0 1

??

0 1 0 10 1 0 1

1 0 0 11 0 0 1 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 0 11 0 0 1 1 0 0 1 1 0 0 1

IncorrectIncorrectFunctionFunction

Rx DataRx Data

0 0 1 10 0 1 1 0 0 1 10 0 1 1 1 1 0 01 1 0 0 1 1 0 01 1 0 01 1 0 01 1 0 0

Decoding Using a Incorrect Code

Example: Spreading

+1+1

-1-1

+1+1

-1-1

+1+1

-1-1

+1+1

-3-3

Spread Waveform Representation ofSpread Waveform Representation ofUser A’s signalUser A’s signal

Analog Signal Formed by the SummationAnalog Signal Formed by the Summationof the Three Spread Signalsof the Three Spread Signals

Spread Waveform Representation ofSpread Waveform Representation ofUser C’s signalUser C’s signal

Spread Waveform Representation ofSpread Waveform Representation ofUser B’s signalUser B’s signal

A=00A=00

Walsh Code forWalsh Code forA = 0101A = 0101

B=10B=10

Walsh Code forWalsh Code forB = 0011B = 0011

C=11C=11

Walsh Code forWalsh Code forC = 0000C = 0000

Despreading

Received Composite SignalReceived Composite Signal

Walsh Code for User A = 0101Walsh Code for User A = 0101

ProductProduct

+1+1

-3-3

+1+1

-1-1

+3+3

-1-1

Average=(5-1)/4=1Average=(5-1)/4=1Average=(5-1)/4=1Average=(5-1)/4=1 Average=(5-1)/4=1Average=(5-1)/4=1Average=(5-1)/4=1Average=(5-1)/4=1

““0”0”““0”0” ““0”0”““0”0”

Pseudorandom Noise (PN) Codes

� Two Short Codes (215 = 32,768)� Termed “I” and “Q” codes (different taps )

� Used for Quadrature Spreading

� Unique offsets serve as identifiers for a Cell or a Sector

� Repeat every 26.67 msec (at a clock rate of 1.2288Mcps)

� One Long Code (242= 4400 Billion)� Used for spreading and scrambling

� Repeats every 41 days (at a clock rate of 1.2288Mcpsat a clock rate of 1.2288Mcps))

PN Code Generation

1 1 0Out

• Seed Register with 001

• Output will be a 7-digit sequence that repeats continually : 1001011

PN Code Generation

Masking

Masking will cause the generator to produce the same sequence, but offset in time

MaskMask

001001

010010

011011

100100

101101

110110

111111

Offset (in chips)Offset (in chips)

77

66

44

55

11

33

22

Transmitted Transmitted

SequenceSequence

10010111001011

00101110010111

10111001011100

01011100101110

11001011100101

01110010111001

11100101110010

Lookup Table for PN Offsets

Quadrature Spreading

To BasebandFilter

I

Q

1 0 1 1 0 0 0 0 1 0 1 1 0

0 1 0 0 0 1 1 1 0 1 0 1 1

0 1 1 0 1 1 1 0 0 1 0 1 1

Symbols Spread byWalsh Chips

0 1 1 0 1 1 1 0 0 1 0 1 1

0 1 1 0 1 1 1 0 0 1 0 1 1 1 1 0 1 1 1 1 0 1 1 1 0 1

0 0 1 0 1 0 0 1 0 0 0 0 0

Offset I PN Code

Offset Q PN Code

QPSK MODULATION USING PN-SHORT CODE

• Quick and Easy Cell Acquisition

• Reuse Walsh Codes

100101001100111010111001010100

100101001100111010111001010100

1001010011001110101110010Offset inincrementsof 64 chips

#1

#2

#3

PN Offset – Cell Identification

CDMA AIR INTERFACE ARCHTECTURE

FORWARD & REVERSE LINK CODES

Coherent / Non-Coherent Detection

SECTION 2HOW CDMA WORKS

LET US PUT EVERYTHING TOGETHER


•Forward link Architecture•Reverse Link Architecture•Logical Channels on Forward Link•Logical Channels on Reverse Link

The CDMA Physical Layer

Terminology: Bit, Symbol and Chip

InformationInformation

A/DA/D

FECFEC

CodeCodeGeneratorGenerator

SpreaderSpreader

Information BitsInformation Bits

CodeCodeSymbolsSymbols

ChipsChipsChipsChips++

MuxMux

PSKPSK

add check bitsadd check bits

CDMA FORWARD LINK ARCHITECTURE

CDMA REVERSE LINK ARCHITECTURE

AIR INTERFACE

Control Channels

Downlink Uplink

Pilot Sync Paging Access

AIR INTERFACE

TRAFFIC CHANNELS

SPEECH or DATA ASSOCIATED SIGNALLING

1 1/2 1/4 1/8 Blank & Burst

Dim & Burst

Power Control

FORWARD LINK CHANNELS IN CDMA-2000

Forward Traffic Code Channel

� 26.67 ms frame period, repeated 75 times a second.

� Pilot channels are kept at 4-6 dB higher then rest of the channels

BB

BB

All 0’s

Walsh W0

1.2288 Mcps

I Pilot PN sequence1.2288 Mcps

Q Pilot PN sequence1.2288 Mcps

To QPSKModulator

Pilot Channel

Sync Channel - W

Needed to achieve code synchronization and timing information.

Sync Channel Message includes : • System Identification

• Network Identification

• Supported protocol revision levels

• Pilot PN sequence offset index

• Long code state

• System time

• Leap seconds

• Offset local time

• Daylight savings time indicator

• Page channel data rate

64

32

� Convolutional encoder not zeroed out after each frame

� No CRC bits at frame level, SOM (Start Of Message)

SOM

31 Information Bits

32 bits / 26.67 ms

BB

BB

Sync ChannelMessage Walsh W32

1.2288Mcps

I Pilot PN sequence1.2288 Mcps

Q Pilot PN sequence1.2288 Mcps

To QPSKModulator

ConvolutionalEncoder

Rate=1/2, K=9

SymbolRepetition

1.2Kbps

2.4Ksps

BlockInter-leaver19.2

Ksps19.2Ksps

Sync Channel Frames

Page Channel - W Base station communicates with the mobiles during Idle Mode.

Page channel message includes :• System and access parameters

• Neighbor list

• Channel list

• Page

• Order

• Channel Assignment

• Data Burst

• Authentication challenge

• SSD (Shared Secret Data) update

• Feature notification

• Null

64

1-7

BB

BB

Paging ChannelMessage

Walsh W1-7

1.2288Mcps

I Pilot PN1.2288 Mcps

Q Pilot PN1.2288 Mcps

To QPSKModulator


Rate=1/2, K=9

SymbolRepetition

4.8/9.6Kbps

9.6/19.2Ksps


Ksps

19.2Ksps

Long Code Decimator

Long Code Generator

1.2288Mcps

64:1Long-code MaskforPaging Channel

Paging Channel

To QPSKModulator

BB

Walsh Wn

1.2288Mcps




Rate=1/2, K=9

SymbolRepetition

BlockInter-leaver 19.2

Ksps

DecimatorLong Code Generator

1.2288Mcps

64:1Long-code Mask

Decimator

Mux

24:1

Power ControlBits (800bps)

BB

Forward Traffic Channel

Reverse Link Code Channels

Reverse Link Code Channels

RFTransmit/Receive

Up/Down Converter

Searcher

Four Fingers

DemodulationProcessor

Deinterleaver&

Viterbi Decoder

P/NSequenceGenerator

Rx Data

Packets

Antenna

REVERSE LINK CHANNELS IN CDMA-2000

Reverse Link Walsh Code

Walsh Code Administration

Walsh Codes have to be Orthogonal

• Walsh codes on the same “row” are Non-Orthogonal

Reserved Walsh Codes

• F-PICH W064

• F-SYNC W3264

• F-PCH W164

• F-TDPICH W16128

• F-QPCH W30128

- 2nd and 3rd F-QPCH W48128 and W112

128

- Non-provisioned F-QPCH Walsh codes is available for traffic

Walsh Functions Lengths

Access Channel

Mobile communications with base station during Idle Mode

Access channel message includes :

• Registration

• Order

• Data Burst

• Origination

• Page response

• Authentication challenge response

• Tail Bits Zero Convolutional Encoder, No CRC Bits At Frame Level

• Preamble Comprised of Zero Filled Frames

88 Information Bits8 TailBits

20 ms

BB

BB

Access ChannelMessage

1.2288Mcps



To QPSKModulator


Rate=1/3, K=9

SymbolRepetition

4.8/9.6Kbps

14.4Ksps


Ksps

64-aryOrthogonalModulator

Long Code Generator

1.2288 McpsLong-code Mask

Access Channel Frames

BB

BB

1.2288Mcps



To QPSKModulator


Rate=1/3, K=9

SymbolRepetition

RS1/RS2


Ksps

64-aryOrthogonalModulator

Long Code Generator

1.2288 McpsLong-code

Mask

DataBurst

Randomizer

28.8Ksps

4.8Ksps

Reverse Traffic Channel

Access Channel 1 PNA Access Channel 2

PNB Access Channel nPNX Traffic Channel 1

PNH Traffic Channel 2PNI Traffic Channel 3

PNJ Traffic Channel m-1PNY Traffic Channel m

PNZ

All MS transmit on same frequency but with different PN codes to create different logical channels. Some channels

marked for Access are used for signaling and control.

Reverse Channel

SECTION 3CALL PROCESSING IN CDMA


•Mobile Initialization•Mobile Registration•Handoff Types•Rake Receiver•Power Control•Vocoding

Overview of Call Processing

MOBILE TRANSITION INTO DIFFERENT STATES

Power - up

Mobile Initialization

State

Mobile IdleState

Mobile System AccessState

Mobile TrafficChannel

State

Mobile Idle Handoff or enable to receive Paging Channel.

Receives acknowledgement to an Access Channel transmission other than Origination or Page response I.e. registration acknowledgement.

Directed to a

Traffic

Channel

Receives Paging

Channel Message :

Originates a cell Registration

Mobile has fully acquired system timing.

Ends use of Traffic Channel

Signaling Services Layer

MOBILE TRANSITION INTO THE IDLE STATE

MOBILE SWITCHED ON

SCAN PN OFFSET 1- 512& MEASURE PILOT SIGNAL

STRENGTH

SELECT BEST SIGNAL PN OFF SET PILOT

READ SYNCHCHANNEL

SID/NIDO.K

READ PAGIING CHANNEL MOBILE IS NOW IN IDLE MODE

NO

YES

SYSTEM DETERMINATION SUBSTATE

NO

MOBILE- PILOT CHANNEL ACQUISITION SUBSTATE

1.SCAN ALL PILOTS

Sync Channel Acquisition Substate

Go to Paging Channel, Get Configured

Mobile Initialization State

Page Channel Monitor & Pilot search

Sub state

Mobile System Access

State

Idle Handoff Sub state

Mobile unable to receive Paging Channel

Mobile receives Acknowledgement to an Access transmission other than Origination or Page Response.

• Call Termination

• Call Origination

• Registration

Another pilot stronger than current pilot

Idle Handoff complete

Mobile has fully acquired system timing

Mobile Idle State

Idle State

System Parameters Message

Neighbor List

Access Parameters Message

CDMA Channel List Message

Global service Redirection Message

Slotted Mode & Quick Paging Channel

Objective• To extend the battery life of a mobile in slotted mode by reducing the time the mobile spends monitoring paging channels.

Slotted Mode• Paging channel divided into slots and slot cycles.Mobile monitors specific slot in a slot cycle.

F-QPCH Functionality• Paging or configuration change indicators is sent out on the F-QPCH 100ms prior to the message on the F-PCH.

• If the mobile cannot detect an indicator to be “OFF”, the mobile will read the F-PCH slot immediately following the F-QPCH slot.

F-PCH & F-QPCH Structure

Access Channel Protocol

Used when mobile contact base station• Quickly

•Avoid Interference

Two protocols• Message or order response access

• Request access

Trial – and - error

Access Procedure

Access Handoff Features

Mobile (MS) searching for pilots Active-,Neighbors-,Remaining State

Origination

MS perform access attempt.Up to 6 strongest pilots ind.

Active pilot in msg capsule

Access Handoff

Mobile Traffic Channel State

Channel Assignment intoSoft Handoff (CAMSHO)

BS sends generalPage to MS

Access EntryHandoff

No

Yes

The Traffic Channel State

From Mobile SystemAccess State

TrafficChannel

InitializationSub state

Waiting forOrder

Sub state

ConversationSub state

Waiting forMobileAnswer

Sub state

ReleaseSub state

To MobileInitialization State

MS cell origination MS

receives an Acknowledge

Order on forward Traffic

Channel

MS user disconnects or MS receives

Release Order

MS receives an Alert Order

MS receives Release Order

MS user Answers

call

MS call termination MS receives an Acknowledge Order on forward traffic

channel

MS receives Release Order

Traffic Channel Assignment Algorithm

Access seizure received on carrier frequency Fk

Calculate downlink loading for F1,F2,…Fk….,Fn normalized

on max_power

Subtract tca_weight from downlink Loading for Fk

Select RF carrier frequency withAvailable traffic channel elements,available packet pipe capacity, and

minimum downlink loading.

Example:

tca _weight = 20

F1 : 30%

F2 : 45% (originating carrier)

F2 vs. F1 : (45-20=25) vs. 30

Traffic Channel assigned to F2

Called Cross Carrier Frequency

Traffic Channel Assignment when selected RF carrier frequency = Fk

Traffic Channel Associated Signaling

When on a traffic channel, associated signaling is used for communication of messages between mobile and base station.

In addition to certain messages transmitted in Idle Mode, other messages are send on the traffic channel :

• Handoff direction

• In-traffic system parameters

• Neighbor list update

• Mobile station registered

• Pilot strength measurement

• Power measurement report

• Handoff completion

Conversation Substate

Messages being sent on the traffic channel

Continuous confirmation of the traffic channel

Locating handoff candidates

Performing handoffs

Power control

Overload control

Other call activities

The Traffic Channel State

Signaling or Secondary Traffic

1 1 2 80 bits 88 bits 12 bits 8 bits

MM 1

TT 0

TM 00

Primary Traffic

CRC Tail

Rate ½ Primary +

Signaling


MM 1

TT 0

TM 01

Primary Traffic

CRC Tail

Rate 1/4 Primary +

Signaling Signaling or Secondary Traffic


MM 1

TT 0

TM 10

Primary Traffic

CRC Tail

Rate 1/8 Primary +


1 1 2 168 bits 12 bits 8 bits

MM 1

TT 0

TM 11

CRC Tail

Blank and Burst

Signaling Traffic

MM = Mixed Mode

0 = Primary Only

1= Primary + Signaling or Secondary

TT = Traffic Type

0 = Signaling

1 = Secondary

TM = Traffic Mode

00 = 80/88

01 = 40/128

10 =16/152

11= 168

Overview of Registration

•NAME•MIN•ESN•Location •Desired Slot Cycle•Station Class Mark•Billing Information

Types of Registration

Power Up

Power Down

Timer Based

Distance Based

Zone Based

Parameter Change

Ordered

Implicit

Traffic Channel

CDMA2000 Handoff Related to Call Processing States

Idle Handoff Access Entry Handoff **

Dormant Handoff

Dormant Handoff

Access Probe HandoffAccess Handoff

Idle State

Update Overhead Information SubstateSystem

Access States Allowed

Handoff Types

Mobile States

Page Response or Origination or

Order/Message Response Substate

Channel Assignment Message or Extended Channel Assignment Message Received

Mobile Station Control on the Traffic Channel

State

Request or Response to send

on Access Channel

Dormant HandoffSoft Handoff

Softer Handoff

Soft Handoff Softer Handoff Hard Handoff

Dormant Handoff

**Access Entry Handoff allowed after receiving a message requiring a response or acknowledgment

Idle Handoffs

A

B

Pilot_B > Pilot_A + 3

dB Must Handoff

Access Handoffs

TIA/EIA-95

Improvements

Perform Idle Handoff here if required

Tx strength of several neighbors

Perform Idle Handoff between probes if necessary

Perform Idle Handoff between probes if necessary

Access Handoff

Channel Assignment into Soft Handoff

Receipt of Page or Subscriber dials #

Update Overhead Information

Begin Access Attempt (TX of 1st Probe)

Continuous Access Attempt(TX of 2nd Probe)

Continuous Access Attempt (TX of 3rd Probe)

Channel Assignment Message

Probe is Acknowledged

IDLE STATE

ACCESSSTATE

Soft Handoffs

F1/F2/F3

F1/F2

F1(Common Carrier)

Carrier is discontinuing – border carrier

Current carrier is blocked – handoff escalation

Why Inter- Frequency Handoff ?

F1/F2/F3Traffic

Cell

F1/F2/F3Traffic

Cell

F1/F2/F3Traffic

Cell

F1/F2/F3Traffic

Cell

F1/F2Traffic

F3 BorderCell

F1/F2Traffic

F3 BorderCell

F1/F2Traffic

Cell

F1/F2Traffic

Cell

F1TrafficF2 Border

Cell

F1Traffic

Cell

F1TrafficF2 Border

Cell

F1Traffic

Cell

Traffic Channel Handoffs


Speech Handler

MSC

Rake Receiver

Base StationTraffic Frames

Semi-Soft vs. Hard Handoff

IS-95B Soft Handoff Algorithm

Excessive handoff may degrade system capacity

IS-95B Soft Handoff Algorithm• Reduce soft handoff activity

• Filter out unnecessary handoffs

• Reduce number of soft handoff legs

• Improve forward link capacity

Ec/Io

PS1

The Pilot Searching Process

Handoff Signaling

Why Power Control ?

Objectives

• Maintain QOS

• Maximize capacity

• Minimize interference

Power Control Algorithms

• Forward Link Power Control (FLPC,FPC)

- a.k.a Downlink Power Control

• Reverse Link Power Control (RPLC,RPC)

- a.k.a.Uplink Power Control

Near-far Problem Path Loss Fading Performance Objectives

Power Control Is Required ?

Power Control

Mobile Tx Power (dBm) =

OPEN LOOPk-Mobile Receive Power (dBm)

+ Parameters+ Access robe Corrections (dB)

+ CLOSED LOOP Corrections (dB)

Reverse Link Power Control

Two separate algorithms

Reverse Open Loop (Autonomous Control)• Performed in the mobile

• Adjust for pathloss

- Output power based on received signal strength

- Tx power = - [Mean Received Signal Strength] + correction_factors

Reverse Closed Loop (Base Station Directed Control)•Base station directs mobile to adjust power

•Controls frame error rate of signal received at the serving base station

•Consists of an inner loop and an outer loop

Reverse Link Closed Loop Power Control

Base station sends power control bits

• 800 controls per second (800 Hz)

Closed Outer Loop (at base station)

• Calculates Ec/Io set point (for R-PICH)

- Based on R-FCH frame error rate

Closed Inner Loop (at base station)•Compare Ec/Io set point with measured Ec/Io

- Send power control bits (up/down) to mobile

Mobile Adjust its power•Based on power control bits from base station

•Step size of is adjustable

Forward Link Power Control

Reverse Link Closed Lop process is adopted

Mobile sends power control bits on R-PICH• 800 control per second (800 Hz)

• Based on Eb/Nt and FER objectives

Base station received power control bits• Variable power step size controlled by the base station

The Rake Receiver

Multipath

Multipath

Correlator 1

Correlator 2

Correlator 3

SearcherCorrelator

COMBINER

Variable Rate Vocoding & Multiplexing

Coding & Compressing

8000 samples/ s. 64 kbps

Sile

nce

Sile

nce

Coding & compression 14.4 kbps Decoding & decompression

Optimally reconstructed human voice

Variable Rate Vocoder

Vocoder Data RatesVocoder Data RatesRate Set 1: 9600bps TX RateRate Set 1: 9600bps TX Rate

Vocoder RateVocoder Rate

855085504000400020002000800800

Tx RateTx Rate

96009600480048002400240012001200

FullFullHalfHalfQuarterQuarterEighthEighth

Vocoder Data RatesVocoder Data RatesRate Set 2: 14.4Kbps TX RateRate Set 2: 14.4Kbps TX Rate

Vocoder RateVocoder Rate

1330013300620062002700270010001000

Tx RateTx Rate

1440014400720072003600360018001800

FullFullHalfHalfQuarterQuarterEighthEighth

Variable Rate Vocoder

24 bits 48 bits 96 bits 96bits 192 bits

20 msec 20 msec 20 msec 20 msec 20 msec

Eight

Rate

Quarter

Rate

Half

Rate

Half

Rate

Full

Rate

Rate Set 1

8 Tail bits1 171 bits 12 bit CRC

Mode Bit

Full Rate

80 bits 8 bit CRC 8 Tail bitsHalf Rate

8 Tail bits40 bitsQuarter Rate

16 bits 8 Tail bitsEighth Rate

Rate Sets

Multiplexing

Signaling or Secondary Traffic


MM 1

TT 0

TM 00

Primary Traffic

CRC Tail

Rate ½ Primary +

Signaling


MM 1

TT 0

TM 01

Primary Traffic

CRC Tail

Rate 1/4 Primary +



MM 1

TT 0

TM 10

Primary Traffic

CRC Tail

Rate 1/8 Primary +


1 1 2 168 bits 12 bits 8 bits

MM 1

TT 0

TM 11

CRC Tail

Blank and Burst

Signaling Traffic

MM = Mixed Mode

0 = Primary Only

1= Primary + Signaling or Secondary

TT = Traffic Type

0 = Signaling

1 = Secondary

TM = Traffic Mode

00 = 80/88

01 = 40/128

10 =16/152

11= 168

Multiplexing

1 124 bits 10 bits 8 bits

MM= 0

Primary Traffic CRC Tail

7200 bps Primary Traffic Only

1 3 54 bits 67 bits 10 bits 8 bits

MM= 1

FM= 000

Primary Traffic CRC TailSignaling Traffic

7200 bps Dim and Burst with rate 1/4

Primary and Signaling Traffic


MM= 1



Primary and Signaling Traffic

FM= 001

MM= 1

1 3 121 bits 10 bits 8 bits

CRC TailSignaling Traffic

7200 bps Blank and Burst with Signaling

Traffic FM= 010

Muliplexing

MM= 0

1 54 bits 10 bits 8 bits

Primary Traffic CRC Tail

3600 bps Primary Traffic only


MM= 1



Primary and Signaling Traffic FM=

000

MM= 1

1 2 52 bits 8 bits 8 bits

CRC TailPrimary Traffic

3600 bps Blank and Burst with Signaling

Traffic FM= 01

SECTION 4INTRODUCTION TO DATA IN CDMA

Section Introduction•DATA Layers•Data and Quality•FCH and SCH •Dormant Mode•MAC and RLP•SARA

MAC and LAC Protocol Layers

Protocol Layers

Quality of Service Function

Radio Link Protocol

Packet Data Traffic

Packet data is bursts of data followed by periods of inactivity

Resources from instantaneously inactive users are reassigned

Inherently a best – effort system

• The system makes the best effort to provide an adequate service to multiple users consistent with scheduling policies and user priorities.

Statistical Gain

Queuing Delay

3G-1X Airlink Overview

. . .

Su

pp

lem

en

tal c

ha

nn

els

InactivityTimer

InactivityTimer

Session EndPPP Disconnect

Data CallReconnections

time

FundamentalChannel

Burst Burst BurstDormant

Data CallOrigination

Data Session

Data Call Data CallData Call

Fundamental Channel - 9.6 KbpsSupplemental Channel - 19.2 - 153.6 Kbps

3G1X Call

Supplemental Air Recourse Allocation

• SARA determines data rate and burst duration of SCH

- Goal is to maximize throughput based on QoS objectives

• First maximum data rate is determined

- Channel elements, Walsh codes, packet pipes etc.

• Then data rate and burst duration

- Maximum data rate and RF conditions.

Supplemental Channels - Configuration

• No SCH

- Voice and low speed data

• Dedicated SCH

- High speed packet or circuit data for one user per SCH at a time

• Shared SCH

- High speed packet data for multiple users on one or more SCHs

Shared Supplemental Channel

Dedicated Supplemental Channel

Accumulative Interference

Data Call With Supplemental Channel

Turbo encoder

-“Two convolution encoders operating in parallel”

Input: turbo interleave

Output:concatenated, repetition and puncturing

-More robust than convolution codes

- Add additional delay to the traffic data

Complex Scrambling

CDMA Capacity

Coverage

(Eb/Io) = (Eb/Io) + Marginreceived required

Strong coding enables operation at lower Eb/Io.

Soft Handoff enables CDMA to provide acceptable level of service with smaller margin.

Radio Frequency Impairments

Total impairment = Thermal noise NO

+ Co – channel interference from

mobiles served by the same

physical antenna face

+ Co – channel interference from

mobiles served by nearby

physical antenna faces

NT

Thermal noise = NO

Total impairment = NT

Reverse Link Pole Capacity

Example 3G-1X Reverse Link Budget Voice

Link Budget Impact of 3G-1X Data

• Traffic channel activity of SCH is assumed to be 1.0

• Data device is expected to be away from the user’s head – body loss is 0dB

• Different data rates and corresponding Eb/Nt

Data rate FER Eb/Nt

19.2kbps 2% 3.4dB

38.4kbps 3% 2.6dB

76.8kbps 5% 1.8dB

153.6kbps 10% 1.0dB

• Turbo Codes

Example 3G-1X Reverse Link Budget-Data________