cdma theory module

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CDMA Theory Module

Unit 1 －－ CDMA Overview

Unit 2 －－ CDMA Basic Principle

Unit 3 －－ CDMA Channel Structure and Modulation

Unit 4 －－ CDMA Key Technology


CDMA Theory Unit 1


The history of mobile communication CDMA evolution path The advantage of CDMA CDMA spectrum usage Role of ZTE in CDMA

Main Content


11GG 22GG 33GG

Analog cellular

DDiiggiittaall cceelllluullaarr DDiiggiittaall cceelllluullaarr

VVooiiccee VVooiiccee //ddaattaa VVooiiccee // hhiigghh ssppeeeedd ddaattaa

AAMMPPSS CCDDMMAA 11XXRRtttt CCDDMMAA22000000

TTAACCSS GGSSMM GGPPRRSS WW__CCDDMMAA

8800’’ 11999922 11999999 22000011 22000033

Evolution of Mobile Communications System

AMPS: Advanced Mobile Phone SystemTACS: Total Access Communication SystemGPRS: General Packet Radio Services

AMPS: Advanced Mobile Phone SystemTACS: Total Access Communication SystemGPRS: General Packet Radio Services


Mobile Communication Standards

2G

FL 3.09Mbps PDRL 1.8 Mbps PD

2.5G 3G

Voice

cdmaOneIS-95-A

••

• High Capacity Voice• 153 kbps PD• RF Backward

Comp.

CDMA20001X

CDMA20001X Rel A

• 2.4 Mbps PDRF Backward Comp.

CDMA2000 1xEV-

IS-95-BKoreaJapan

• Voice• 64 kbps Packet• RF Backward

Compatible

••• Backward Comp.

CDMA2000 1xEV- DO Rel

• FL 3.09 Mbps PD• RL 1.8 Mbps PD• Backward Comp.

CDMA2000 Rel D

cdmaOneIS-95-A

•

cdmaOneIS-95-A

•14.4 kbps CSD

•••

CDMA20001X

•••

CDMA20001X Rel. 0

• 307.2 kbps Packet• Backward Comp.

CDMA20001X Rel A

CDMA20001X Rel.A

•

CDMA2000 1xEV-

•

CDMA2000 1xEVDO Rel. 0

IS-95-BKoreaJapan

•••

IS-95-BKoreaJapan

•••

••

CDMA2000 1xEV- DO Rel

••

CDMA2000 1xEVDO Rev.A

•••

CDMA2000 1xEVDV Rel D

•••

D

•


CDMA Status in The World

• At present, CDMA commercial networks are established in about 50 countries or area, almost 20% of all users in the world.

• At present, CDMA commercial networks are established in about 50 countries or area, almost 20% of all users in the world.


High privacy,hard to wiretappingHigh privacy,hard to wiretapping

Spread code

Informationsignal

TX

Demodulatedsignal

RX

Spread code

Spread signalEach user is below the noise deeply

Advantages of CDMA(1)


Good voice quality, uses 8k QCELP, 13K QCELP,8k EVRC, voice coding - the best coding method in the world.

Good voice quality, uses 8k QCELP, 13K QCELP,8k EVRC, voice coding - the best coding method in the world.

Voice quality(MOS) 64k

PCM13kGSM

8k QCELPCDMA

13k QCELPCDMA

8kEVRCCDMA



Frequency reuse factor is 1;network design and expanding become much easier

Frequency reuse factor is 1;network design and expanding become much easier

Advantages of CDMA (3)

AMPS, D-AMPS, N-AMPS

CDMA

30 30 10 kHz

200 kHz

1250 kHz

1 3 1 Users

8 Users

20 Users1

1

11

1

11

11

1

11

1

1

12

34

43

2

56

17

Typical Frequency Reuse N=7



GSM


CDMA System”make before break”---- soft handoff

CDMA System”make before break”---- soft handoff

Use soft handoff, decrease drop-call rateUse soft handoff, decrease drop-call rate

Advantages of CDMA

Other systems: “make after break” --------hard handoff

Other systems: “make after break” --------hard handoff


Perfect Power Control and voice activation make the MS

Power low, healthy for body—green mobile phone.

Perfect Power Control and voice activation make the MS

Power low, healthy for body—green mobile phone.


Mean Power Max Power

GSM: 125mW 2W

CDMA: 2mW 200mW

Mean Power Max Power

GSM: 125mW 2W

CDMA: 2mW 200mW


large coveragealmost 2 times than GSM, save money for operator

large coveragealmost 2 times than GSM, save money for operator

Example:cover 1000 km2 ： GSM need 200 BTS ， CDMA only need 50 BTS Attention: exact result need “Link Budget ”

Example:cover 1000 km2 ： GSM need 200 BTS ， CDMA only need 50 BTS Attention: exact result need “Link Budget ”



High spectrum capacity ， 8--10 times than AMPS,4—6 times than GSM

High spectrum capacity ， 8--10 times than AMPS,4—6 times than GSM

FrequencyTime

Power

FrequencyTime

Power

FrequencyTime

Power

FDMA

TDMA

CDMA

FDMA---Different user use different frequency

TACS 、 AMPS

TDMA---Different user use different time slot of one frequency

GSM 、 DAMPS

CDMA---Different user use same frequency at the same time,but with different spreading code



95A 95B

Software update Replace MS to

get new service

Almost free

95B 1X

Add 1X channel

board Software update

Replace MS to get new service

inexpensive

1X 1XEV

Add 1XEV channel board

Software update

Replace MS to

get new service

inexpensive

TechnicalScheme ：

High speed packet switching structure, smooth migration to 3G ! the operator’s benefit is protected at the most !

High speed packet switching structure, smooth migration to 3G ! the operator’s benefit is protected at the most !

Economic

Scheme ：



CDMA 800 MHz Cellular Spectrum Usage

• All CDMA RF carriers are 1.25 MHz. Wide• Between CDMA carriers, no guard band

Possible CDMA Center Freq. Assignments

Channel Numbers

Forward link (i.e., cell site transmits)Reverse link (i.e., mobile transmits)824MHz

849MHz

869MHz

894MHz

otherusesA” A”A B A’ B’

1 10 10 1.5 2.5

A B A’ B’

1 10 10 1.5 2.5

991

10231 333

334

666667

716717

799

991

10231 333

334

666667

716717

799

~300 kHz. “guard bands” possibly required if adjacent-frequency signals are non-CDMA (AMPS, TDMA, ESMR, etc.)


CDMA Frequency ChannelAssignment at 800 MHz Cellular

1

334

667

991

1023

333

666

715

799

716

ChannelNumbers

A Band B Band A’A” B’

1019 37 78 119 160 201 242 283 384 425 466 507 548 589 630 691 777

CDMA A-Band Carriers CDMA B-Band Carriers

8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 9 9 8

* **** Requires frequency coordination with

non-cellular interferers

** Requires frequency coordination with A-band carrier

A Band Primary Channel 283A Band Secondary Channel 691

B Band Primary Channel 384B Band Secondary Channel 777

736

Up link: 825.00MHz+0.03MHz*N

Down link: 870.00MHz+0.03MHz*N

Channel number?

Channel number? Center

frequency

Centerfrequency


ZTE’s Activities in CDMA

In 1995, CDMA mobile telecommunication project was started In November, 1999, ZTE signed the “Agreement on CDMA R&D” with

Qualcomm In August, 2000, the first field trial was set up. In September, 2000 ， ZTE presented the first CDMA handset with UIM

(User Identification Module) in the world. In January, 2001, the first cdma2000-1x call was passed through in lab In March, 2001, ZTE cdma2000-1x realized the integrated transmission of

voice, data & image.The data rate reach up to 153.6Kbps. In 2003, ZTE first EV-DO all-IP trial network was set up.

In 1995, CDMA mobile telecommunication project was started In November, 1999, ZTE signed the “Agreement on CDMA R&D” with

Qualcomm In August, 2000, the first field trial was set up. In September, 2000 ， ZTE presented the first CDMA handset with UIM

(User Identification Module) in the world. In January, 2001, the first cdma2000-1x call was passed through in lab In March, 2001, ZTE cdma2000-1x realized the integrated transmission of

voice, data & image.The data rate reach up to 153.6Kbps. In 2003, ZTE first EV-DO all-IP trial network was set up.


ZTE － A Famous CDMA Brand

2G/3G Terminals

Abis

Abis

Abis

PSTN/PLMN

BSC/ PCF (1X)

Internet

Router Router

IP

IP

BTS （ IS-95 ）

BSC （ IS-95 ）

Abis

E1Um

IS95

Um

IS2000E1 STM-1

E1 STM-1

Ethernet

MSC/VLR HLR/AUC

PDSN/FA

AAA

HA

OMC

SC

WINBTS （ IS-9

5 ）

BSC/ PCF (1X)

BTS （ 1X ）

BTS （ 1X ）

E1

Server

Ethernet


Network Optimization Simulation

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B

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LH

B

B

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GB

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ZTE Supply All Service

Network Planning

Network SimulationWireless Network Optimization

Maintenance Optimization


ZTE Supply All Products


CDMA Theory Unit 2


Main Content

Definitions of CDMA and How to realize

Spread spectrum modulation

Spreading codes used in CDMA

Vocoding in CDMA


Multiple Access

• Types of Media -- Examples:

– Twisted pair - copper

– Coaxial cable

– Fiber optic cable

– Air interface (radio signals)

• Advantages of Multiple Access

– Increased capacity: serve more users

– Reduced capital requirements since fewer media can carry the traffic

– Decreased per-user expense

– Easier to manage and administer

Each pair of users enjoys a dedicated,

private circuit through the transmission

medium, unaware that the other users exist.

Since the beginning of telephony and radio, system operators have tried to squeeze the maximum amount of traffic over each circuit.

Multiple Access: Simultaneous private use of a transmission medium by multiple, independent users.

Transmission

Medium


Channels

• FDMA Frequency Division Multiple Access– Each user on a different frequency– A channel is a frequency

• TDMA Time Division Multiple Access– Each user on a different window period in

time (“time slot”)– A channel is a specific time slot on a

specific frequency

• CDMA Code Division Multiple Access– A channel is a unique code pattern– Each user uses the same frequency all the

time, but mixed with different distinguishing code patterns Frequency

Time

Power

FrequencyTime

Power

FrequencyTime

Power

FDMA

TDMA

CDMA

Channel: An individually-assigned, dedicated pathway through a transmission medium for one user’s information.

The transmission medium is a resource that can be subdivided into individual channels according to the technology used.


Defining Our Terms• CDMA Channel or CDMA Carrier or CDMA Frequency

– Duplex channel made of two 1.25 MHz-wide bands of electromagnetic spectrum, one for Base Station to Mobile Station communication (called the FORWARD LINK or the DOWNLINK) and another for Mobile Station to Base Station communication (called the REVERSE LINK or the UPLINK)

– In 800 Cellular these two simplex 1.25 MHz bands are 45 MHz apart

– In 1900 MHz PCS they are 80 MHz apart

• CDMA Forward Channel

– 1.25 MHz Forward Link

• CDMA Reverse Channel

– 1.25 MHz Reverse Link

• CDMA Code Channel

– Each individual stream of 0’s and 1’s contained in either the CDMA Forward Channel or in the CDMA Reverse Channel

– Code Channels are characterized (made unique) by mathematical codes

– Code channels in the forward link: Pilot, Sync, Paging and Forward Traffic channels

– Code channels in the reverse link: Access and Reverse Traffic channels

45 or 80 MHz

CDMA CHANNELCDMA

ReverseChannel 1.25 MHz

CDMAForwardChannel 1.25 MHz


Main Content




Vocoding in CDMA


What is Spread Spectrum

ORIGINATING SITE DESTINATION

SpreadingSequence

SpreadingSequence

InputData

RecoveredData

Spread Data Stream

Definition:Spread spectrum technique ,employ a transmission bandwidth that is several orders of magnitude greater than the minimum required signal bandwidth.

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


SHANON Formula

Spread Spectrum Principles

Where, C is capacity of channel, b/s B is signal bandwidth, Hz S is average power for signal, W N is average power for noise, W

C=B*log2(1+S/N)

It is the basic principle and theory for spread spectrum communications.

It is the basic principle and theory for spread spectrum communications.


How DSSS Spectrum Change

User 1

Code 1

Composite

Time Frequency

+=

Direct Sequence CDMA


CDMA Is a Spread-Spectrum System

Traditional technologies try to squeeze the signal into the minimum required bandwidth

Direct-Sequence Spread spectrum systems mix their input data with a fast spreading sequence and transmit a wideband signal

The spreading sequence is independently regenerated at the receiver and mixed with the incoming wideband signal to recover the original data

Spread Spectrum Payoff:Processing Gain

Spread SpectrumTRADITIONAL COMMUNICATIONS SYSTEM

SlowInformation

Sent

TX

SlowInformationRecovered

RX

NarrowbandSignal

SPREAD-SPECTRUM SYSTEM

FastSpreadingSequence

SlowInformation

Sent

TX

SlowInformationRecovered

RX

FastSpreadingSequence

Wideband Signal



1.25 MHz30 KHz

Power is “Spread” Over a Larger Bandwidth

MATHHAMMER

MATHHAMMER



Many code channels are individually“spread” and then added together tocreate a “composite signal”


Anything We Can Do, We Can Undo

• Any data bit stream can be combined with a spreading sequence

• The resulting signal can be de-spread and the data stream recovered if the original spreading sequence is available and properly synchronized

• After de-spreading, the original data stream is recovered intact


SpreadingSequence

SpreadingSequence

InputData

(Base Band)

RecoveredData

(Base Band)

Spread Data Stream(Base Band + Spreading Sequence)


CDMA Spreading PrincipleUsing Multiple Codes

• Multiple spreading sequences can be applied in succession and then reapplied in opposite order to recover the original data stream.

• The spreading sequences can have different desired properties.

• All spreading sequences originally used must be available in proper synchronization at the recovering destination.

SpreadingSequence

A

SpreadingSequence

B

SpreadingSequence

C

SpreadingSequence

C

SpreadingSequence

B

SpreadingSequence

A

InputData

X

RecoveredData

X

X+A X+A+B X+A+B+C X+A+B X+ASpread-Spectrum Chip Streams



“Shipping and Receiving” via CDMA

• 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 codes.

Fed

Ex

Data Mailer

Fed

Ex

DataMailer

Shipping Receiving


Main Content




Vocoding in CDMA


• Spreading code chip speed ： 1.2288Mc/s ；

• Spreading codes used ：

Forward link—Walsh code & Short PN Reverse link—Long PN

• Spreading code chip speed ： 1.2288Mc/s ；

• Spreading codes used ：

Forward link—Walsh code & Short PN Reverse link—Long PN

Spreading Codes in CDMA

Spreading codes selection is the key of spread Spectrum modulation!

Spreading codes selection is the key of spread Spectrum modulation!


Walsh Code Definition

• The Walsh function is named after Walsh, the mathematician who proved it an orthogonal function in 1923. It is expressed as Walsh (n,t), n for the serial number. The CDMA system of IS-95 is differentiated with the Walsh function.

Walsh code is an orthogonal square matrix. It is just composed of +1(0) and –1(1).

• The Walsh function is named after Walsh, the mathematician who proved it an orthogonal function in 1923. It is expressed as Walsh (n,t), n for the serial number. The CDMA system of IS-95 is differentiated with the Walsh function.

Walsh code is an orthogonal square matrix. It is just composed of +1(0) and –1(1).

0110

1100

1010

0000

10

000

Hn Hn

H2n = ___

Hn Hn

H1 H2 H4


Walsh Codes• 64 Sequences, each 64 chips long

– A chip is a binary digit (0 or 1)

• Each Walsh Code is Orthogonal to all other Walsh Codes

– This means that it is possible to recognize and therefore extract a particular Walsh code from a mixture of other Walsh codes which are “filtered out” in the process

– Two same-length binary strings are orthogonal if the result of XORing them has the same number of 0s as 1s

WALSH CODES # ---------------------------------- 64-Chip Sequence ------------------------------------------ 0 0000000000000000000000000000000000000000000000000000000000000000 1 0101010101010101010101010101010101010101010101010101010101010101 2 0011001100110011001100110011001100110011001100110011001100110011 3 0110011001100110011001100110011001100110011001100110011001100110 4 0000111100001111000011110000111100001111000011110000111100001111 5 0101101001011010010110100101101001011010010110100101101001011010 6 0011110000111100001111000011110000111100001111000011110000111100 7 0110100101101001011010010110100101101001011010010110100101101001 8 0000000011111111000000001111111100000000111111110000000011111111 9 010101011010101001010101101010100101010110101010010101011010101010 001100111100110000110011110011000011001111001100001100111100110011 011001101001100101100110100110010110011010011001011001101001100112 000011111111000000001111111100000000111111110000000011111111000013 010110101010010101011010101001010101101010100101010110101010010114 001111001100001100111100110000110011110011000011001111001100001115 011010011001011001101001100101100110100110010110011010011001011016 000000000000000011111111111111110000000000000000111111111111111117 010101010101010110101010101010100101010101010101101010101010101018 001100110011001111001100110011000011001100110011110011001100110019 011001100110011010011001100110010110011001100110100110011001100120 000011110000111111110000111100000000111100001111111100001111000021 010110100101101010100101101001010101101001011010101001011010010122 001111000011110011000011110000110011110000111100110000111100001123 011010010110100110010110100101100110100101101001100101101001011024 000000001111111111111111000000000000000011111111111111110000000025 010101011010101010101010010101010101010110101010101010100101010126 001100111100110011001100001100110011001111001100110011000011001127 011001101001100110011001011001100110011010011001100110010110011028 000011111111000011110000000011110000111111110000111100000000111129 010110101010010110100101010110100101101010100101101001010101101030 001111001100001111000011001111000011110011000011110000110011110031 011010011001011010010110011010010110100110010110100101100110100132 000000000000000000000000000000001111111111111111111111111111111133 010101010101010101010101010101011010101010101010101010101010101034 001100110011001100110011001100111100110011001100110011001100110035 011001100110011001100110011001101001100110011001100110011001100136 000011110000111100001111000011111111000011110000111100001111000037 010110100101101001011010010110101010010110100101101001011010010138 001111000011110000111100001111001100001111000011110000111100001139 011010010110100101101001011010011001011010010110100101101001011040 000000001111111100000000111111111111111100000000111111110000000041 010101011010101001010101101010101010101001010101101010100101010142 001100111100110000110011110011001100110000110011110011000011001143 011001101001100101100110100110011001100101100110100110010110011044 000011111111000000001111111100001111000000001111111100000000111145 010110101010010101011010101001011010010101011010101001010101101046 001111001100001100111100110000111100001100111100110000110011110047 011010011001011001101001100101101001011001101001100101100110100148 000000000000000011111111111111111111111111111111000000000000000049 010101010101010110101010101010101010101010101010010101010101010150 001100110011001111001100110011001100110011001100001100110011001151 011001100110011010011001100110011001100110011001011001100110011052 000011110000111111110000111100001111000011110000000011110000111153 010110100101101010100101101001011010010110100101010110100101101054 001111000011110011000011110000111100001111000011001111000011110055 011010010110100110010110100101101001011010010110011010010110100156 000000001111111111111111000000001111111100000000000000001111111157 010101011010101010101010010101011010101001010101010101011010101058 001100111100110011001100001100111100110000110011001100111100110059 011001101001100110011001011001101001100101100110011001101001100160 000011111111000011110000000011111111000000001111000011111111000061 010110101010010110100101010110101010010101011010010110101010010162 001111001100001111000011001111001100001100111100001111001100001163 0110100110010110100101100110100110010110011010010110100110010110

EXAMPLE:

Correlation of Walsh Code #23 with Walsh Code #59

#23 0110100101101001100101101001011001101001011010011001011010010110#59 0110011010011001100110010110011010011001011001100110011010011001XOR 0000111111110000000011111111000011110000000011111111000000001111

Correlation Results: 32 1’s, 32 0’s: Orthogonal!!


0 1 2 3 4 5 6 7 1 1

8 9 0 11 1 1 12 3 4 5

1 1 1 16 7 8 9

2 2 2 20 1 2 3

2 2 2 24 5 6 7

2 2 3 38 9 0 1

3 3 3 32 3 4 5

3 3 3 36 7 8 9

4 4 4 40 1 2 3

4 4 4 44 5 6 7

4 4 5 58 9 0 1

5 5 5 52 3 4 5

5 5 5 56 7 8 9

6 6 6 60 1 2 3

0123

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

4567

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

89

1011

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

12131415

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

16171819

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

20212223

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

24252627

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

28293031

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 0 1 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

32333435

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

36373839

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

40414243

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

44454647

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

48495051

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

52535455

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

56575859

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

60616263

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 0 1 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

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

1 1 1 11 0 1 01 1 0 01 0 0 1

1 1 1 11 0 1 01 1 0 01 0 0 1

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

Walsh Code Table


Walsh Code Function in Forward Link

• A Mobile Station receives a Forward Channel from a sector in a Base Station.

• The Forward Channel carries a composite signal of up to 64 forward code channels.

• Some code channels are traffic channels and others are overhead channels.

• A set of 64 mathematical codes is needed to differentiate the 64 possible forward code channels.– The codes in this set are called “Walsh Codes”

SyncPilot

FW Traffic(for user #1)

Paging




Short PN: 4-bits register example

The PN sequences are deterministic and periodic.

– The length of the generated string is 2n-1, where “n” is the number of elements in the register

– The number of ones in the sequence are equal to the number of zeros plus 1

1 0010 0110 1101 1011 0100 1011 0110 1111 1111 110

10 0 00 0100 100

1 1001 000

0 100p1 p2 p3 p4

p4 p5 p2 p3

p2 p3

p4

p5 = p1 + p4

p4


Short PN Sequences

• Together, they can be considered a two-dimensional binary “vector” with distinct I and Q component sequences, each 32,768 chips long

• Each Short PN Sequence (and, as a matter of fact, any sequence) correlates with itself perfectly if compared at a timing offset of 0 chips

• Each Short PN Sequence is special: Orthogonal to a copy of itself that has been offset by any number of chips (other than 0)

IQ

32,768 chips long26 2/3 ms.

(75 repetitions in 2 sec.)

IQIQ

100% Correlation: All bits = 0

Short PN Sequence vs. Itself @ 0 Offset

IQIQ

Orthogonal: 16,384 1’s + 16,384 0’s

Short PN Sequence vs. Itself @ Any Offset

Unique Properties:

The two Short PN Sequences, I and Q, are 32,768 chips long


Short PN Function in Forward Link

• Each Sector in each Base Station is transmitting a Forward Traffic Channel containing up to 64 forward code channels.

• A Mobile Station must be able to discriminate between different Sectors of different Base Stations.

• Two binary digit sequences called the I and Q Short PN Sequences (or Short PN Codes) are defined for the purpose of identifying sectors of different base stations.

• These Short PN Sequences can be used in 512 different ways in a CDMA system. Each one of them constitutes a mathematical code which can be used to identify a particular sector.

A B

Up to 64Code Channels

Up to 64Code Channels


Long PN:4-bits shift register example

( XOR )

mask

XOROriginal PNsequence

New PNsequence

AND AND AND AND

1 0010 0110 1101 1011 0100 1011 0110 1111 1111 110

10 0 00 0100 100

1 1001 000

0 100

Attention:different mask lead to different offset!Attention:different mask lead to different offset!


The Long PN Sequence

• Each mobile station uses a unique User Long Code Sequence generated by applying a mask, based on its 32-bit ESN, to the 42-bit Long Code Generator which was synchronized with the CDMA system during the mobile station initialization.

• Generated at 1.2288 Mcps, this sequence requires 41 days, 10 hours, 12 minutes and 19.4 seconds to complete.

• Portions of the User Long Codes generated by different mobile stations for the duration of a call are not exactly orthogonal but are sufficiently different to permit reliable decoding on the reverse link.

Long Code Register (@ 1.2288 MCPS)

Public Long Code Mask (STATIC)

User Long CodeSequence

(@1.2288 MCPS)

1 1 0 0 0 1 1 0 0 0 E S N

AND

=S U M

Modulo-2 Addition


Long PN Functionin Reverse Link

• The CDMA system must be able to identify each Mobile Station that may attempt to communicate with a Base Station.

• A very large number of Mobile Stations will be in the market.

• One binary digit sequence called the Long PN Sequence (or Long PN Code) is defined for the purpose of uniquely identifying each possible reverse code channel.

• This sequence is extremely long and can be used in trillions of different ways. Each one of them constitutes a mathematical code which can be used to identify a particular user (and is then called a User Long Code) or a particular “user Reverse Traffic channel”.

RV Trafficfrom M.S.

#1837732008RV Trafficfrom M.S.

#1997061104

RV Trafficfrom M.S.

#1994011508

System AccessAttempt by M.S.

#2000071301(on access channel #1)


Main Content




Vocoding in CDMA


Variable Rate Vocoding

• CDMA uses a superior Variable Rate Vocoder– Full rate during speech– Low rates in speech pauses– Increased capacity– More natural sound

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


Variable Rate Voice Bit and PCM

•

• Where is vocoder?

BTS BSCBSC MSCMSC

Analog voice

Variable RatePCM

cdma theory module

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