01CDMA Theory

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Copyright 2003, ZTE CORPORATION

Welcome to ZTE

Technical TrainingCenter




Class Rules

Class Hours: 8:40 AM - 11:50 AM

14:10-17:20 PM

Little Breaks:

Several short breaks throughout class

Set mobile on silence or vibrator mode

No smoking in classroom




BSS Course Agenda

Course A: CDMA Basic Theory

Course B: ZXC10-BSS Hardware Introduction

and OperationCourse C:1x Packet Data ServiceCourse D: Network design and optimization




Course A:CDMA Basic Theory

I. CDMA Overview

II. CDMA Basic PrincipleIII. CDMA Channel Structure and Modulation

IV. CDMA Key Technology




I. CDMA Overview




Objectives

Upon completion of this lesson, the student

will be able to master:

-- the history of mobile communication-- the advantage of CDMA

-- CDMA migration from 2G to 3G

-- CDMA spectrum usage

-- the role of ZTE in CDMA


http://slidepdf.com/reader/full/01cdma-theory 7/192Copyright 2003, ZTE CORPORATION

• Mobility：

– flexible and convenient，global personal

communication

• Poor environment and conditions：

– Co-channel interference, multi-path(space and

time)shadow effect and delay, power change and

other noise

• Multiple MS and channels：

– Interference、near and far effect

• Limit of frequency resources

• Reliability is important

– registration, handoff, switching

Characteristics of Mobile

Communication



11GG 22GG 33GG

Analog

cellularDDiiggiittaall cceelllluullaarr DDiiggiittaall cceelllluullaarr

VVooiiccee VVooiiccee / / ddaattaa VViiooccee / / 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 System

GPRS: General Packet Radio Services



CDMA-Its History & Status

• 1993, the first CDMA standard IS-95 was issued;

• In 1995, CDMA technology was put into commercialization in Hongkongand America on large scale;

• In 1997, CDMA trial networks were constructed in Beijing, Xi‘an, Shanghaiand Guangzhou in China;

• In April, 2001, China Unicom began to construct CDMA networks—thelargest in the world;

• At present, CDMA commercial networks are established in about 40

countries or area, almost 20% of all users in the world.



Frequency

reuse factor is 1;

network design

and expanding

become mucheasier

Advantages of CDMA(1)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

4

32

56

17

Typical Frequency Reuse N=7



Vulnerability:C/I @ 17 dB

Vulnerability:C/I @ 12-14 dB

Vulnerability:Eb/No @ 6--7 dB

GSM



Large capacity:

8--10 times than AMPS4 — 6 times than GSM

Power

Power

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

Advantages of CDMA(2)



large coverage

almost 2 times than GSM, save money for

operator

Example:cover 1000 km2：

GSM need 200 BTS

CDMA only need 50 BTSAttention: exact result need “Link Budget ”




High privacy,hard to wiretapping

Spread code

Informationsignal

TX

Demodulatedsignal

RX

Spread code

Spread signalEach user is belowthe noise deeply




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

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

Use soft handoff, decrease drop-call rate




Good voice quality, use 8k,13K(QCELP,EVRC)voice

coding — the best coding method in the world.

Voice quality

(MOS)

64k

PCM13k

GSM

8k

CDMA13k

CDMA

8kEVRC

CDMA




Perfect Power Control and voice activation make the MS

Power low, healthy for human body — green mobile phone.


Mean Power Max Power

GSM: 125mW 2W

CDMA: 2mW 200mW



95A 95B

Software update

Replace MS to

get new service

95B 1X Add 1X channel

board

Software update

Replace MS to ge

new service

1X 1XEV Add 1XEV

channel board

Software update

Replace MS to

get new service

inexpesive

Technical

Scheme：

Smooth migration to 3G and the operator’s benefit

is protected at the most

Almost free inexpensive

Economic

Scheme：




Definition of Some Terms（1） • Channel

– Duplex channel made of two 1.2288MHz-wide bands of electromagneticspectrum:

one for Base Station to Mobile Station communication (called theFORWARD LINK or the DOWNLINK) and another for Mobile Station to

Base Station communication (called the REVERSE LINK or the UPLINK) • Carrier or Frequency

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

– In 1900 MHz PCS they are 80 MHz apart

– In 450MHz,they are 10MHz apart

45 or 80 or 10 MHz

CDMA CHANNELCDMA

ReverseChannel1.25 MHz

CDMAForwardChannel1.25 MHz



CDMA Frequency Calculation：

450MHzBS receiver(Uplink): 450.00+0.025(N-1)

BS sender(downlink): 460.00+0.025(N-1)

800MHzBS receiver(Uplink): 825.00+0.03N

BS sender(downlink):870.00+0.03N

1900MHzBS receiver(Uplink): 1850.00+0.05NBS sender(downlink):1930.00+0.05N

Definition of Some Terms（2）



CDMA 800 MHz Cellular Spectrum

Usage

• All CDMA RF carriers are 1.25 MHz. wide – Can serve ~20 users /8 kb vocoder

Possible CDMACenter Freq. Assignments

ChannelNumbers

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

9 9 1

1 0 2 3

1

3 3 3

3 3 4

6 6 6

6 6 7

7 1 6

7 1 7

7 9 9

9 9 1

1 0 2 3

1

3 3 3

3 3 4

6 6 6

6 6 7

7 1 6

7 1 7

7 9 9

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



CDMA Frequency Channel

Assignment at 800 MHz Cellular

IS-95 Recommends to Start CDMA deployment with Either the Primary or the Secondary Channel

1

3 3 4

6 6 7

9 9 1

1 0 2 3

3 3 3

6 6 6

7 1 5

7 9 9

7 1 6

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



CDMA PCS 1900 MHz Spectrum

UsageGuard Bands

Forward link (i.e., cell site transmits)Reverse link (i.e., mobile transmits)1850MHz

B

T

A

B

T

A

B

T

A

B

T

A

B

T

A

B

T

A

Paired Bands

MTA BTAMTABTA MTAMTA

1910MHz

1930MHz

1990MHz

Data Voice

A D B E F C A D B E F C

15 51010 1515151515 555 55

Licensed Licensed

Unlicensed 0

ChannelNumbers 2

9 9

3 0 0

4 0 0

6 9 9

7 0 0

8 0 0

9 0 0

1 1 9 9

0

2 9 9

3 0 0

4 0 0

6 9 9

7 0 0

8 0 0

9 0 0

1 1 9 9



CDMA 1900 MHz Cellular

Spectrum Assignment

1895M 1900M

925 950 975

1980M

925 950 975

（Downlink ：1975-1980）（Uplink ：1895-1900）

1975M

N=



Definition of some Terms（3）

• CDMA Code Channel

– All CDMA users transmit and receive on the same

channel,but they are separated based on their digital

code.Because CDMA allocates individual users differentdigital codes rather than divide the spectrum based on

frequency or time.

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

and Forward Traffic channels

– Code channels in the reverse link: Access and Reverse

Traffic channels



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 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.

The certificates acquired:

– CDMA 800M ZXC10-MSC/VLR,HLR/AUC,BSC, BTS network access

licenses

– CDMA 800M/1.9G ZXC10-BTS typeapproval certificates



ZTE

A Famous Brand in CDMA

2G/3G

终端

Abis

Abis

Abis

PSTN/PLMN

BSC/ PCF (1X)

Internet

路由器路由器

IP

IP

BTS（IS-95）

BSC（IS-95）

Abis

E1Um

IS95

Um

IS2000 E1

STM-1

E1

STM-1

Ethernet

MSC/VLR HLR/AUC

PDSN/FA

AAA

HA

OMC

SC

WIN BTS（IS-95）

BSC/ PCF (1X)

BTS（1X）

BTS（1X）

E1

业务服务器

Ethernet



II. CDMA

BASIC PRINCIPLE



Objectives

• Describe the differences between CDMA, TDMA,

FDMA• What is spread spectrum modulation

• Identify we use DSSS in CDMA

• Know Walsh codes

• Know short PN and long PN• Know the purpose of Vo-coding

Upon completion of this lesson, the student will be ableto:




Contents

2.1 The principle of Spread spectrum

2.2 Walsh Code and its application

2.3 PN Code and its application

2.4 The Communication Model of 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 themaximum amount of traffic over each circuit.

Multiple Access: Simultaneous private use of a transmissionmedium 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 intime (―time slot‖)

– A channel is a specific time slot on aspecific frequency

• CDMA Code Division Multiple Access

– A channel is a unique code pattern

– Each user uses the same frequency all thetime, but mixed with differentdistinguishing code patterns

Power

Power

Power

FDMA

TDMA

CDMA

Channel: An individually-assigned, dedicatedpathway through a transmission

medium for one user’s information. The transmission medium is a resource that can be subdividedinto 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

ReverseChannel1.25 MHz

CDMAForwardChannel1.25 MHz




CDMA Is a Spread-Spectrum System

Traditional technologies try tosqueeze the signal into theminimum required bandwidth

Direct-Sequence Spread spectrumsystems mix their input data witha fast spreading sequence andtransmit a wideband signal

The spreading sequence isindependently regenerated at the

receiver and mixed with theincoming wideband signal torecover 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




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 signalbandwidth.Sender combines data with a fast spreading sequence,transmitsspread data streamReceiver intercepts the stream,uses same spreading sequence toextract original data




-1 1 1-1 1Spreading

-1 1

1 -1 1 -1

Spread Process

Digital Signal Spreading Signal

Spreading Code

1 -1 -1




-1 1 -11-1 -11 1 -1 -1 11-1 1-1 1De-spreading

-1 1 -11-1 -11 1

1 -1 1 -1

1 1 1 1

Integrator

-4 4

0 0

Adjudge-1 1

De-spread Process




Spread Spectrum PrinciplesSHANON Formula

It is the landmark paper of information theory, amathematical theory of spectrum communication.

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

Where,

C is capacity of channel, b/s

B is signal bandwidth, Hz

S is average power for signal

N is average power for noise




Digital Waveform and Spectrumg(t)

0 T0τ0 /2

T0=5τ0E

t

0 2T0τ0 /2

2T0=10τ0E

t

g(t)

0 T0τ1 /2

T0=10τ0E

t

τ1=τ0 /2

g(t)

0 f 0

Bf 0

2E/5

f

A(f)

0

1/τ0 Bf 0

E/5

f

A(f)

f 0 /2

A(f)

0

1/τ1 Bf 1E/5

f f 1

Pulse width is τ0, pulse period is T0 =5τ0

Pulse width is τ0, pulse period is 2T0

Pulse width is τ0 /2, pulse period is T0

The bandwidth depends on the pulse width. So

we use the narrower pulse sequence for

modulating the carrier to achieve wider

bandwidth .

The pulse spectrum lines density depends on

the pulse sequence period.

If the pulse period increase or the pulse width

decrease, the amplitude of the spectrum will

decrease.

Spread Spectrum




How DSSS Spectrum Change

User 1

Code 1

Composite

Time Frequency

+

=

Direct Sequence CDMA




f

Signal Spectrum Before Decoding

Signal Spectrum Before SS

f

S（f ）

f0

Signal

f f0

Signal Spectrum after SS

S（f ）

Signal

Signal Spectrum After Decoding

f

S（f ）

f0

Signal

Noise

S（f ）

f0

Signal

Noise

Signal Pulse Noise Other Noise

Spectrum Variation of Spread & De-spread




Illustration to SS Principle(1)

1.25 MHz

9.6 KHz

Power is ―Spread‖ Over a Larger Bandwidth




Many code channels are individually

“spread” and then added together tocreate a ―composite signal‖





UNWANTED POWERFROM OTHER SOURCES

Using the ―right‖ mathematical Sequences, any Code Channelcan be extracted from the receivedcomposite signal

Eb/No

PG





Spectrum Usage and Capacity:• Each wireless technology (AMPS,

NAMPS, D-AMPS, GSM, CDMA)uses a specific modulation type with itsown unique signal characteristics

• The total traffic capacity of a wirelesssystem is determined largely by radiosignal characteristics and RF design

•RF signal vulnerability to Interferencedictates how much interference can betolerated, and therefore how far apartsame-frequency cells must be spaced

• For a specific S/N level, the SignalBandwidth determines how many RFsignals will “fit” in the operator’s

licensed spectrum

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

1 1 1

1

12

34

4

32

56

17




Vulnerability:C/I @ 17 dB

Vulnerability:C/I @ 12-14 dB

Vulnerability:Eb/No @ 6--7 dB

GSM

17 dB = 101.7 @ 50

14 dB = 101.4 @ 25

12 dB = 101.2 @ 16




Relationship Between Eb/N0 and S/N

Eb =

S

R

Signal Power

Bit Rate = N0 =

N

W

Noise Power

Bandwidth =

=S

R

W

NX =

S

N

W

RX

S

R

N

W

Eb

N0

=

Signal to Noise

ProcessingGain

E / t

B / t=

W

R

=1,250,000

14,400

= 87 =1.94

10 = 19.4dB

W R

= 1,250,0009,600

= 130 =2.11

10 = 21.1dB 8 Kb vocoder

(Full Rate)

13 Kb vocoder(Full Rate)




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 theoriginal spreading sequence is available and properly synchronized

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

ORIGINATING SITE DESTINATION

SpreadingSequence

SpreadingSequence

InputData

(Base Band)

RecoveredData

(Base Band)

Spread Data Stream(Base Band + Spreading Sequence)




CDMA Spreading Principle

Using Multiple Codes

• Multiple spreading sequences can be applied in succession and thenreapplied 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+A

Spread-Spectrum Chip StreamsORIGINATING SITE DESTINATION




“Shipping and Receiving” via

CDMA

• Whether in shipping and receiving or in CDMA, packaging isextremely 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.

F e d E x

Data Mailer

F e d E x

DataMailer

Shipping Receiving




Advantages of Spread Spectrum

Avoid interference arising from jamming signal or multi-path effects

SS and demodulation, noise is suppressed and filtered

resist intercept and capture: difficult to detect Achieve Privacy: Difficult to demodulate

Implement Multiple Access

Improve Frequency Reuse

Enlarge Capacity




Discriminating Among Forward

Code Channels

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

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

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

• 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‖

SyncPilotFW Traffic

(for user #1)

Paging

FW Traffic(for user #2)

FW Traffic(for user #3)




Discriminating Among Base

Station

• A mobile Station is surrounded by Base Stations, all of them transmitting

on the same CDMA Frequency.• 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 Sectorsof 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 CDMAsystem. Each one of them constitutes a mathematical code which can beused to identify a particular sector.

A B

Up to 64Code Channels

Up to 64Code Channels

Discriminating Among Reverse




Discriminating Among Reverse

Code Channels• The CDMA system must be able to

identify each Mobile Station that mayattempt to communicate with a BaseStation.

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

• One binary digit sequence called theLong PN Sequence (or Long PN Code)is defined for the purpose of uniquelyidentifying each possible reverse codechannel.

• This sequence is extremely long and

can be used in trillions of differentways. Each one of them constitutes amathematical code which can be usedto identify a particular user (and is thencalled 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)




CDMA Spread Code Selection

Walsh Codes

Short PNSequences

Long PNSequences

Type ofSequence

MutuallyOrthogonal

Orthogonalwith itself atany time shiftvalue except 0

near-orthogonalif shifted

SpecialProperties

64

2

1

HowMany

64 chips1/19,200

sec.

32,768chips26-2/3 ms75x in 2sec.

242 chips~41 days

Length

OrthogonalModulation(information

carrier)

QuadratureSpreading(Zero offset)

Distinguish

users

Reverse LinkFunction

User identitywithin cell‘ssignal

DistinguishCells &Sectors

Data Scrambling to avoid stringsof 1‘s or 0‘s

Forward LinkFunction




Contents








Definition of Walsh Function

The application of Walsh Function




Walsh function is formed by recursion relationship ofHadamard matrix.

Hadamard matrix is an orthogonal square matrix.It is justcomposed of +1(0) and –1(1).

Definition of Walsh code

0 1 1 0

1 1 0 0

1 0 1 0

0 0 0 0

1 0

0 0 0

H n H n

H 2n = ___

H n H n

W l h C d




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 01010101010101010101010101010101010101010101010101010101010101012 00110011001100110011001100110011001100110011001100110011001100113 01100110011001100110011001100110011001100110011001100110011001104 00001111000011110000111100001111000011110000111100001111000011115 01011010010110100101101001011010010110100101101001011010010110106 00111100001111000011110000111100001111000011110000111100001111007 01101001011010010110100101101001011010010110100101101001011010018 00000000111111110000000011111111000000001111111100000000111111119 0101010110101010010101011010101001010101101010100101010110101010

10 001100111100110000110011110011000011001111001100001100111100110011 011001101001100101100110100110010110011010011001011001101001100112 000011111111000000001111111100000000111111110000000011111111000013 010110101010010101011010101001010101101010100101010110101010010114 001111001100001100111100110000110011110011000011001111001100001115 011010011001011001101001100101100110100110010110011010011001011016 000000000000000011111111111111110000000000000000111111111111111117 010101010101010110101010101010100101010101010101101010101010101018 001100110011001111001100110011000011001100110011110011001100110019 011001100110011010011001100110010110011001100110100110011001100120 000011110000111111110000111100000000111100001111111100001111000021 0101101001011010101001011010010101011010010110101010010110100101

22 001111000011110011000011110000110011110000111100110000111100001123 011010010110100110010110100101100110100101101001100101101001011024 000000001111111111111111000000000000000011111111111111110000000025 010101011010101010101010010101010101010110101010101010100101010126 001100111100110011001100001100110011001111001100110011000011001127 011001101001100110011001011001100110011010011001100110010110011028 000011111111000011110000000011110000111111110000111100000000111129 010110101010010110100101010110100101101010100101101001010101101030 001111001100001111000011001111000011110011000011110000110011110031 011010011001011010010110011010010110100110010110100101100110100132 000000000000000000000000000000001111111111111111111111111111111133 010101010101010101010101010101011010101010101010101010101010101034 001100110011001100110011001100111100110011001100110011001100110035 011001100110011001100110011001101001100110011001100110011001100136 000011110000111100001111000011111111000011110000111100001111000037 010110100101101001011010010110101010010110100101101001011010010138 001111000011110000111100001111001100001111000011110000111100001139 011010010110100101101001011010011001011010010110100101101001011040 000000001111111100000000111111111111111100000000111111110000000041 010101011010101001010101101010101010101001010101101010100101010142 0011001111001100001100111100110011001100001100111100110000110011

43 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 0110011010011001100110010110011010011001011001100110011010011001

XOR 0000111111110000000011111111000011110000000011111111000000001111

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

C l ti d O th lit




Correlation and Orthogonality

Code #23 0110100101101001100101101001011001101001011010011001011010010110

–(Code #23) 1001011010010110011010010110100110010110100101100110100101101001

Code #59 0110011010011001100110010110011010011001011001100110011010011001

PARALLEL

XOR: all 0s

Correlation: 100%(100% match)

ORTHOGONAL

XOR: half 0s, half 1s

Correlation: 0%(50% match, 50% no-match)

ANTI-PARALLEL

XOR: all 1s

Correlation: –100%(100% no-match)

#23

#23

–(#23)

#23

#23

#59

Correlation is a measure of the similarity between two binary strings

Properties of the Walsh Codes




Properties of the Walsh Codes° When a Walsh code is XORed chip by chip with itself,

the result is all 0‘s (100% correlation)

° When a Walsh code is XORed chip by chip with itslogical negation, the result is all 1‘s ( –100% correlation)

° When a Walsh code is XORed chip by chip with anyother code or its logical negation, the result is half 0‘sand half 1‘s (0% correlation)

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

0 0 0 0

0 1 0 1

0 1 0 1

0 1 0 1

0 1 0 1

0 0 0 0

0 0 1 1

0 1 0 1

0 1 1 0

0 1 1 0

0 1 0 1

0 0 1 1

1 1 1 1

0 1 0 1

1 0 1 0

1 0 1 0

0 1 0 1

1 1 1 1

1 1 0 0

0 1 0 1

1 0 0 1

1 0 0 1

0 1 0 1

1 1 0 0

Walsh Code Table




0 1 2 3 4 5 6 71 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

242526

27

0 0 0 00 1 0 10 0 1 1

0 1 1 0

0 0 0 00 1 0 10 0 1 1

0 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 0

1 0 0 1

1 1 1 11 0 1 01 1 0 0

1 0 0 1

1 1 1 11 0 1 01 1 0 0

1 0 0 1

0 0 0 00 1 0 10 0 1 1

0 1 1 0

0 0 0 00 1 0 10 0 1 1

0 1 1 0

0 0 0 00 1 0 10 0 1 1

0 1 1 0

0 0 0 00 1 0 10 0 1 1

0 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 0

1 0 0 1

1 1 1 11 0 1 01 1 0 0

1 0 0 1

1 1 1 11 0 1 01 1 0 0

1 0 0 1

0 0 0 00 1 0 10 0 1 1

0 1 1 0

0 0 0 00 1 0 10 0 1 1

0 1 1 028293031

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

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

4445

4647

0 0 0 00 1 0 1

0 0 1 10 1 1 0

1 1 1 11 0 1 0

1 1 0 01 0 0 1

1 1 1 11 0 1 0

1 1 0 01 0 0 1

0 0 0 00 1 0 1

0 0 1 10 1 1 0

0 0 0 00 1 0 1

0 0 1 10 1 1 0

1 1 1 11 0 1 0

1 1 0 01 0 0 1

1 1 1 11 0 1 0

1 1 0 01 0 0 1

0 0 0 00 1 0 1

0 0 1 10 1 1 0

1 1 1 11 0 1 0

1 1 0 01 0 0 1

0 0 0 00 1 0 1

0 0 1 10 1 1 0

0 0 0 00 1 0 1

0 0 1 10 1 1 0

1 1 1 11 0 1 0

1 1 0 01 0 0 1

1 1 1 11 0 1 0

1 1 0 01 0 0 1

0 0 0 00 1 0 1

0 0 1 10 1 1 0

0 0 0 00 1 0 1

0 0 1 10 1 1 0

1 1 1 11 0 1 0

1 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 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

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




64-rank Walsh code

• Forward Link: spread spectrum and indicate forwardchannel

• Backward Link: Orthogonal modulation

the Application of Walsh code




Contents








PN (pseudo noise )sequence

m sequence

phase

mask

orthogonal、self-correlation、cross-correlation




Similar with noise sequence property

Seemingly like random sequence,but it is

regular and periodic binary code sequence

PN Sequence




• m sequence is an important binary pseudo noise sequence

• m sequence is the short term of ―Maximal-Length linear

feedback shift register sequence‖

• Definition:If the output sequence period of r-stage linearfeedback shift register is P=2r – 1，Then this sequence is m

sequence

• m sequence generator consists of three parts:shift register,

modulo-2 Adder, feedback path

m Sequence Definition




Output

X=X1 X2 X3 X4=10001001101011110+ + +

We suppose the initial state of the register

X1X2X3X4=0001

Four-Stage Linear Feedback Shift Register

X1 X2 X3 X4

Clock Pulse

Output

Modulo-2 Adder +




Orthogonal

Orthogonal DefinitionFrom the standpoint of mathematics,two lines plumb each other

From the standpoint of analogical,compare with two random line or row,if the

number of the same digits and different digits are equal,we call it orthogonal.

In CDMA system,in order to protect less interference between

signals,signals between each other should be orthogonal

Sequence 1: 1 0 0 1 1 0 0 0

OrthogonalSequence 2: 0 0 1 1 0 0 0 1




Self-correlation & Cross-correlation

Self-correlation refers to the degree of correspondence or comparability

between a sequence and a phase-shifted replica of itself

In CDMA system,should select the good Autocorrelation code to insure

demodulation and distinguish at the receiver side

Cross-Correlation refers to the correlation or comparability between two

different signals

In CDMA system,different user should select less Cross-correlation signal

as a code




Mask:• Different mask can make the different phase for m sequence.

• In CDMA system,the mask of different user is calculated bythe ESN in the mobile phone

Phase: • Different phase of difference sequence identify different base

station and user

Two conceptions




The basic property of m sequence

Pseudo noise sequence

Period：P=2r-1，r is the stage of shift register

When the period is very long, m sequence is almostorthogonal

The self correlation of m sequence is very well but the cross

correlation is weak.That means if two m sequence withdifferent phase,it is almost orthogonal

Sh t PN S




Short PN Sequences

• Together, they can be considereda two-dimensional binary ―vector ‖ with distinct I and Q componentsequences, each 32,768 chipslong

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

• Each Short PN Sequence is

special: Orthogonal to a copy of itself that has been offset by anynumber of chips (other than 0)

IQ

32,768 chips long

262

/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 andQ, are 32,768 chips long

Short PN: 4-bits register example




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 zeroes in the sequence is equal to the

number of ones minus 1

1 0010 011

0 110

1 101

1 010

0 101

1 011

0 111

1 111

1 110

10 0 0

0 010

0 100

1 100

1 000

0 100p1 p2 p3 p4

p4 p5 p2 p3

p2

p3

p4

p5 = p1 + p4

p4

Th L PN S




The Long PN Sequence

• Each mobile station uses a unique User Long Code Sequence generated byapplying 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 stationinitialization.

• Generated at 1.2288 Mcps, this sequence requires 41 days, 10 hours, 12minutes 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 differentto 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 P E R M U T E D E S N

AND

=S U M

Modulo-2 Addition




Long PN:4-bits shift register example

XOR)

mask

XOROriginal PN

sequence

New PNsequence

AND AND AND AND

1 001

0 011

0 110

1 101

1 010

0 101

1 011

0 111

1 111

1 110

10 0 0

0 010

0 100

1 100

1 000

0 100

Attention:different mask lead to different offset!




PN code application in CDMA

PN code used in CDMA systemLong code：242 – 1 (r = 42)

Short code：215 (r = 15)

Different purpose

---Forward channel

long code : scramble

short code :orthogonal modulation and identify basestation

---Reverse channel

long code :spread spectrum and identify user

short code :orthogonal modulation




Contents








Information Stream

SpeechCoding

ChannelCoding

Scramble SpreadSpectrum

Modulation RFtransmit

Channeldecoding

De-scramble

De-spreadSpectrum

De-Modulation

RFreceive

Information Stream

CDMA Communication Model

Speechdecoding




Coding Technology

In Digital communication coding technology,include two types:

Speech coding is critical to digital transmission.CDMA system use an

efficient method of speech coding and extensive error recovery

techniques to overcome the harsh nature of the radio channel.

The objective of speech coding is not only to maintain speech quality but also to reduce the quantity of transmitting data.

Channel coding usually falls into two classes:Block interleaver codes

and Convolutional codes.

The objective of channel coding is adding additional

supervising bits in the information stream to ensure get correct

signal at receive side.




Speech Coding

• Speech coding algorithms (digital compression) are necessary toincrease cellular system capacity.

• Coding must also ensure reasonable fidelity, that is, a maximum

level of quality as perceived by the user.

• Coding can be performed in a variety of ways (for example,waveform, time or frequency domain).

• Vocoders transmit parameters which control reproduction of voiceinstead of the explicit, point-by-point waveform description.

A-to-DCONVERTER

64 Kbps

VOCODE

R

“Codebook”

Instruction8Kbps

64 Kbps

MTX

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 CDMAframes

DSP QCELP VOCODER

Codebook

PitchFilter

FormantFilter

Coded Result Feed-back

20ms Sample






• The output is 20 ms frames at fixed rates: Full Rate, 1/2 Rate , 1/4Rate , 1/8 Rate, & Blank

• CRC is added to all the frames for the 13 kb vocoder, but only to theFull and 1/2 rate frames for the 8 kb vocoder.

• CRC is not added to the lower rate frames in the 8 kb vocoder, but that

is ok because they consist mostly of background noise and have ahigher processing gain.

• Current vocoder rates are 8kbps, 13kbps, and 8kbps EVRC (EnhancedVariable Rate Coder)

Rate Set 2 Frame Sizesbits

Full Rate Frame

1/2 Rate Frame

1/4 Rt.

1/836

72

144

288

Rate Set 1 Frame Sizesbits

Full Rate Frame

1/2 Rate Frame

1/4 Rt.

1/824

48

96

192




Variable Rate Voice Bit and PCM

Where is Vocoder?

BTS BSC MSC

Analog voice

Variable Rate PCM

Interleaving Method




Convolutional Coding & Interleaving

Bits to be Txed:

Convolutionally

Encoded:

Interleaved:

Bits Rxed:

De-Interleaved:

Viterbi Decoded:

Example:

E n c o d e

C on v ol u t i on a

l

I n t e r l e a v

e r

D e -

I n t e r l e a v e r

D e c o d e r

H

e l l o …

HHEELLLLOO FFOOLLKKSS

ELSOLHLOFK LEOLSHOLKF

EL SOL HLOFK LEOLSHOLKF

HHEELLL – OO FFO – LLKK- S

HELLO FOLKS

HELLO FOLKS




Channel Coding

-Convolutional Encoder

D DD

g0

g1

c0

c1

c2

Constraint length(K) = Shift Register Number + 1

Code length(N) = input information bit + supervising bit

Code rate(R) = input information bit/code length

From this figure:

Constraint length(K) = 4

Code length(N) =3

Code rate=1/3




Block Interleaver principle:input according to row and output according tocolumnsFor example: An Origination stream 1 1 0 1 0 0 1 1 0 1 0 0 1 1 1 0,arrangein 4 by 4 matrix

1 1 0 1

0 0 1 1

0 1 0 01 1 1 0

1 x 0 1

0 x 1 1

0 x 0 0

1 x 1 0

Interference sequence: 1 0 0 1 x x x x 0 1 0 1 1 1 0 0

Output from receiver matrix：1 x 0 1 0 x 1 1 0 x 0 0 1 x 1 0

Channel Coding

-Block Interleaver Encoder




Convolutional Encoder & Interleaver Encode

Convolutional Encoder: increase the reliability but reduce

the transmitting efficiency,because each code stream adds

supervising bit for rectified

Block Interleaver Encoder: not change the efficiency but

have some delays,because the transmitter and receiver

must process to writing first and then reading




Scramble

The paging channel also includes many import informationsuch as user‘s IMSI,In order to keep the user‘s information

secret ,we use the data scrambling.




Spread Spectrum

Spread code rate: 1.2288Mcps

Spread codeForward Link:Walsh codeReverse Link: Long PN code




Modulation-QPSK&OQPSK

WalshFunction

1.2288 Mcps

19.2 kspsfrom PowerControl Mux

I-Channel Pilot PN Sequence1.2288 Mcps

BasebandFilter

Baseband

Filter

I

Q

S

I

Q

Q-Channel Pilot PN Sequence1.2288 Mcps

cos(2pfct)

sin(2pfct)

GAIN

The forward traffic channel is combined with two different PN sequences: ―I‖

and ―Q‖ Baseband filtering ensures the waveforms are contained within the 1.25 MHzfrequency range

The final step is to convert the two baseband signals to radio frequency (RF)in the 800 MHz or 1900 MHz range




III. CDMA CHANNEL

STRUCTUREAND MODULATION

Objectives




Upon completion of this lesson, the student will be able to

master:

Objectives

-- The forward channel in IS-95

Pilot ;Sync ; Paging and Traffic

-- The reverse channel in IS-95Access; Traffic

-- CDMA Call Processing

-- New Channels in CDMA20001X




Contents

3.1 IS-95 CDMA Channels

3.1.1 Forward CDMA Channels3.1.2 Reverse CDMA Channels





IS-95 CDMA Channels




Pilot Channel

Function: obtains a phase offset by short PN sequences,in order to identifydifferent base station.

obtains basis timing information

assisted handoff:mobile station use pilot strength(signal strength

comparisons between base stations) to identify handoff candidatesand to perform soft handoffs

Characteristic:

Uncoded natured of pilot signal,that means the pilot is a ―structural beacon‖which does not contain a character steam.

transmitted constantly by the base station

use Walsh code 0.




Pilot Channel Generation

• The Walsh code zero spreading sequence is applied to the Pilot

• The use of short PN sequence offsets allows for up to 512 distinctPilots per CDMA channel

• The PN offset index value (0-511 inclusive) for a given pilot PN

sequence is multiplied by 64 to determine the actual offset – Example: 15 (offset index) x 64 = 960 PN chips

– Result: The start of the pilot PN sequence will be delayed960 chips x 0.8138 microseconds per chip = 781.25microsecond

PilotChannel(All 0’s)

1.2288Mcps

I PN

Q PN

WalshFunction 0




Sync Channel

Once a strong pilot channel is located,the mobile station listens to thecorresponding sync channel for system information.

This information transmitted at a rate of 1200bps,is contained in the sync

channel message.

The duration of the sync channel frames matches the period of repetition

of the short PN codes transmitted on the pilot channel.

Therefore,once the mobile station acquires synchronization with the pilot

channel,the synchronization with the sync channel is immediately known.

This action facilitates the acquisition of the sync channel by the mobile

station




Sync Channel(Cont.)

Function: Carries a data stream of essential system identification and

parameter information used by mobiles during system

acquisition stage

PILOT_PN(9bits)

SYS_TIME(36bits)

LC_STATE(42bits)

PRAT(2bits)

Characteristic:

Bit rate is 1200 bps

Sync channel has a frame duration of 26.666ms,matches

the the period of Short PN Sequences

(Acquired Pilot)

Sync Channel

S Ch l M




Sync Channel MessagePILOT_PN(Pilot PN Sequence Offset Index)

Set to the pilot PN offset for the base station (in units of 64 chips),assigned by the network planner

LC_STATE ( Long Code State )Provides the mobile station with the base station long code state at the

time given by the SYS_TIME field, generated dynamically

SYS_TIME (System Time )GPS system-wide time as 320 ms after the end of the last super-framecontaining any part of this message, minus the pilot PN offset, in units of80 ms, generated dynamically

PRAT (Paging Channel Data Rate )

The data rate of the paging channel for this system, determined by thenetwork planner,00 if 9600 bps;01 if 4800 bps

S Ch l G i




Sync Channel Generation

1200 bps

Walsh Function 32

1.2288 Mcps

I PN

Convolutional

Encoder andRepetition

BlockInterleaver

R = 1/2 K=9

ModulationSymbols

4800 sps 4800 sps

Bits Chips

Q PN

16*8

P i Ch l




Paging Channels

There is one paging channel per sector per CDMA carrier

The Paging Channel uses Walsh code 1 up to 7,unused

paging channels can be used as forward traffic channel

Transmits information at a fixed data rate of either 9600 or4800 bps,as specified by the ―PRAT‖ parameter sent in thesync channel message

Paging Channel

Used by the base station to

transmit system overhead informationand mobile station-specific messages.

P i Ch l (C t )




Paging Channels(Cont.) The paging channel originates at the base station.A

paging channel notifies mobile stations that they are

receiving an incoming call.

Once the mobile station accepts the page,a traffic

channel is assigned by the base station for the mobilestation to use.

The base station sends the following messages to all of

the paging channels:

System parameters message

Access parameters message

CDMA channel list message

P i Ch l O h d M




Paging Channel Overhead Message

System parameters messageContains the most important CDMA configurationparameters

Access parameters messageDefines parameters used by the mobile stations whentransmitting to the base station on the access channel

CDMA channel list message

Defines all the CDMA(frequency)channels supported bythis base station

Paging Channel OverheadM




Messages

Mobile-Station-DirectedMessages

OverheadMessages

Access Parameters Message

System Parameters Message

CDMA Channel List Message

Extended System Parameters Message

Extended Neighbor List Message

ConfigurationParameterMessages

Global Service Redirection Message

PagingMessages

ACC_MSG_SEQ

CONFIG_MSG_SEQ

P i Ch l G ti




Paging Channel Generation

Walsh code #1 is used to spread the data. This results in an increase to1.2288 Mcps

The Rate 1/2 convolutional encoder doubles the bit rate.

If the 4800 bps rate is used, the repetition process doubles the rate again, sothat, at either rate, 384 modulation symbols per Paging Channel frame result

384 modulation symbols per frame times 50 frames per second = 19.2Ksps

9600 bps

4800 bps

Walsh

function

1.2288Mcps

Q PN

1.2288Mcps

19.2 Ksps

19.2Ksps Paging Channel

Address Mask

R = 1/2 K=9

Decimator

ConvolutionalEncoder &Repetition

I PN

BlockInterleaving

Scrambling

Long PN Code

Generator




Paging Channel Mask

PCN: Paging channel numberPILOT_PN: Pilot short PN code offset index

1100011001101 00000 PCN 000000000000 PILOT_PN

08920212324282941

Paging Channel is scrambled by the long code,offset by amask constructed as follows:

Data Scrambling




Data Scrambling

Data scrambling is accomplished by modulo-2 addition(XOR),one input is a

modulation symbol(19.2ksps) coming out of the block interleaver,anotherinput is a random sequence,which created by decimator on long codegeneration.That means,Use the 64 times decimator to pickup the first chip ofeach 64 chips to form a random sequence.So the random sequence rate is19.2kcps.(1.2288/64)

BlockInterleaver

LongCode PN

Generator

19.2 KspsModulationSymbols

User AddressMask (ESN)

Decimator

Divideby 64

19.2Ksps

1.2288Mcps

19.2Ksps

Data scrambling function:

Because the pagingchannel includes manyimportant informationsuch as user‘s IMSI,in

order to assure the

use‘s informationsecret,we use the datascrambling.

F d T ffi Ch l




Forward Traffic Channels

• Used for the transmission of user and signaling information to a specificmobile station during a call.

• Maximum number of traffic channels: 64 minus one Pilot channel, oneSync channel, and 1 Paging channel.

– This leaves each CDMA frequency with at least 55 traffic channels.

– Unused paging channels can provide up to 6 additional channels.

Forward Traffic Channel


Sync

Paging



Pilot

•

CDMA Cell Site

F d T ffi Ch l G ti




Forward Traffic Channel Generation

Walshfunction

Power Control

Bit

I PN

9600 bps 4800 bps2400 bps1200 bps(Vocoder) Convolutional

Encoding andRepetition

1.2288McpsLong PN Code

Generation800 Hz

R = 1/2, K=9

Q PN

Decimator DecimatorUser Address

Mask

(ESN-based)

19.2 ksps

1.2288Mcps

Scrambling

bits symbols chips

19.2 ksps

CHANNEL ELEMENT

MUX

Block

Interleaving

19.2 Ksps

F d t ffi h l f t t




Forward traffic channel frame structure

F d T ffi Ch l M k




Forward Traffic Channel Mask

A forward traffic channel is scrambled with the long code,offsetby a mask constructed as follows:

Permuted ESN=E0,E31,E22,….E27,E18,E9

Po er Control S b channel




Power Control Sub-channel

• Base station receiver estimates received signal strength of mobile over

a 1.25 ms period (800/s)• A power control subchannel is transmitted continuously to MS

– A power up/down command is sent 800 times a second

• Uncoded to ensure rapid detection and response by the MS

19.2 Kspsfrom BlockInterleaver

1.2288 McpsUser LongCode

Decimator

ScrambledModulationSymbol orPowerControl Bit

19.2Ksps

Decimator

Data ScramblingMUX

800 Hz MuxTiming

Power ControlBit (800 bps)

Divide by 64 Divide by 24

19.2 Ksps

Power Control Sub channel




Power Control Sub-channelThe power control subchannel is included by forward traffic channel,by use

a power control bit to indicate power up/down of MS transmit power.

Each traffic channel frame(20ms) consist of 16 power control group(each

group length 1.25ms),so the rate of power control is 16*(1s/20ms)=800bps

1.Every 1.25ms(800 times per second)the BS estimates the received signalstrength on the reverse traffic channel of a particular mobile station

2.Based on this estimation,the base station determines whether that mobile

station should increase or decrease its transmission power

3.A power up(0) or power down(1) one-bit command is sent by the base

station to that mobile station 800 times a second on the corresponding

forward traffic channel.This constitutes the ―Power control subchannel‖ for

that mobile station.

Orthogonal Spreading




Orthogonal Spreading

• Each symbol output from the Mux is exclusive XORed by the assignedWalsh function

• Walsh function has fixed chip rate of 1.2288 Mcps

• Channels are distinguished from each other by Walsh function

• Bandwidth used greatly exceeds source rate

To QuadratureSpreading19.2 Ksps

MUX

1.2288Mcps

Walsh Functionfrom Index

Wt800 Hz Mux

Timing

Power ControlBit (800 bps)

ScrambledData

Q adrat re Spreading & Baseband Filtering




Quadrature Spreading & Baseband Filtering

WalshFunction

1.2288 Mcps

19.2 kspsfrom PowerControl Mux


BasebandFilter

Baseband

Filter

I

Q

S

I

Q

Q-Channel Pilot PN Sequence1.2288 Mcps

cos(2pfct)

sin(2pfct)

GAIN

The forward traffic channel is combined with two different PN sequences: ―I‖

and ―Q‖ Baseband filtering ensures the waveforms are contained within the 1.25 MHzfrequency range

The final step is to convert the two baseband signals to radio frequency (RF)in the 800 MHz or 1900 MHz range

QPSK Modulation




QPSK ModulationQuadri-Phase Shift Key (QPSK) Modulation

BASEBAND: The total frequency band occupied by the aggregate of all

the information signals used to modulate a carrier

FILTER:Electronic circuit devised to modify the frequency distribution of a

signal spectrum

BASEBAND FILTER:filter(used in quadrature modulation)that limits the

input signal to the SyQuest band +-T/2,where T is the transmitted pulse rate.

GAIN CONTROL: the gain of the overhead channels(pilot,sync,and

paging)in the composite I and Q is set.The gain of each forward traffic

channel is constantly adjusted by the reverse link power control process.

Composite “I” and “Q”




Composite I and Q • Each channel card has a

combiner and works in aserial array to combine the Iand Q signals for all forwardchannels in a partitionsector or cell.

•The baseband I and Qsignals for all channel cardsare sent to the COREmodule to be multiplexedtogether based on the PNoffset.

• This ensures that a mobilestation does not mistakenlydecode the signal from achannel with the sameWalsh code from the wrongbase station.

Pilot

Channel

WalshCode

SyncChannel

WalshCode

Paging

Channel(s)

WalshCode

Forward Traffic

Channel(s)

WalshCode

“I” PN Code

“Q” PN Code

Composite“I”

Composite“Q”

F d Ch l D d l ti




Forward Channel Demodulation

IS-95A/J-STD-008 requires a minimum of four processing elements thatcan be independently directed:

•Three elements must be capable of demodulating multipath components

•One must be a ―searcher‖ that scans and estimates signal strength at eachpilot PN sequence offset

Correlator1

Correlator2

Correlator3

SearchCorrelator

De-InterleaverViterbi

Decoder VocoderSpeechOutput

Mobile Receiver

C o m b i n e r

Contents




Contents


3.1.1 Forward CDMA Channels

3.1.2 Reverse CDMA Channels


Access Channels




Access Channels

• Used by the mobile station to: – Initiate communication with the base station not yet in a Call (such

as transmit registration requests, call setup requests/origination message )

– Respond to Paging Channel messages

• Has a fixed data rate of 4800 bps

• Although a sector can have up to seven paging channels, and each

paging channel can have up to 32 access channels, nearly all systems

today use only one paging channel per sector and only one access

channel per paging channel.

4800 bps

Access Channel Generation




28.8kspsConvolutional

Encoder &Repetition

R = 1/3

1.2288Mcps

Access ChannelLong Code Mask

Long PN CodeGenerator

28.8ksps Orthogonal

Modulation

307.2kcps

1.2288Mcps

Q PN (No Offset)

I PN (No Offset)

D

1/2 PNChipDelay

BlockInterleaver

Access ChannelInformation

(88 bits/Frame)

4.8 kpbs

DirectSequenceSpreading

Access Channel Generation

• Message attempts are randomized to reduce probability of collision• Two message types:

– A response message (in response to a base station message)

– A request message (sent autonomously by the mobile station)

32*18

64 ary Orthogonal Modulation




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

Symbols

3544 Walsh Lookup TableWalshChip within aWalsh Function

01 2 345 6 7

11

89 0 1

11 1 1

23 4 5

11 1 1

67 8 9

22 2 2

01 2 3

22 2 2

45 6 7

22 3 3

89 0 1

33 3 3

23 4 5

33 3 3

67 8 9

44 4 4

01 2 3

44 4 4

45 6 7

44 5 5

89 0 1

55 5 5

23 4 5

55 5 5

67 8 9

66 6 6

01 2 3

0

1

2

3

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

4

5

6

7

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

8

9

10

11

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

12

13

14

15

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

Wals

16

17

18

19

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

h

Fu

20

21

22

23

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

ncti

24

25

26

27

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

on I

28

29

30

31

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

nde

x

32

33

34

35

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

36

37

38

39

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

40

41

42

43

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

4445

46

47

00 0 001 0 1

00 1 1

01 1 0

11 1 110 1 0

11 0 0

10 0 1

11 1 110 1 0

11 0 0

10 0 1

00 0 001 0 1

00 1 1

01 1 0

00 0 001 0 1

00 1 1

01 1 0

11 1 110 1 0

11 0 0

10 0 1

11 1 110 1 0

11 0 0

10 0 1

00 0 001 0 1

00 1 1

01 1 0

11 1 110 1 0

11 0 0

10 0 1

00 0 001 0 1

00 1 1

01 1 0

00 0 001 0 1

00 1 1

01 1 0

11 1 110 1 0

11 0 0

10 0 1

11 1 110 1 0

11 0 0

10 0 1

00 0 001 0 1

00 1 1

01 1 0

00 0 001 0 1

00 1 1

01 1 0

11 1 110 1 0

11 0 0

10 0 1

48

49

50

51

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

52

53

54

55

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

56

57

58

59

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

60

61

62

63

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

11 1 1

10 1 0

11 0 0

10 0 1

11 1 1

10 1 0

11 0 0

10 0 1

00 0 0

01 0 1

00 1 1

01 1 0

1 0 0 0 1 . . . 1 1 0 1 0

64 Chip Pattern of

Walsh Code # 35

64-ary Orthogonal Modulation

• Out of the block interleaver,the data rate is 28800bps,for every six

symbols input,one Walsh code is output – Six code symbols are converted to a decimal number from 0~63

– This number is used as an index into a Walsh lookup talbe

– The 64 Walsh chips corresponding to that index are output

– after orthogonal modulation,the symbol rate is 28800/6 ×64＝307.2kbps.

Access Channel Long Code Mask




Access Channel Long Code Mask

An Access Channel is scrambled by the longcode, offset by a mask constructed as follows:

Where:

ACN is the Access Channel Number,

PCN is the Number of the associated Paging Channel

BASE_ID is the base station identification number, and

PILOT_PN is the Pilot short PN code offset index

1 1 0 0 0 1 1 1 1 PCNACN BASE_ID PILOT_PN

41 33 32 028 27 25 24 9 8

Reverse Traffic Channels




Reverse Traffic Channels

Used when a call is in progress to send:

• Voice traffic from the subscriber

• Response to commands/queries from the base station

• Requests to the base station

Supports variable data rate operation for:

• A mobile station using the 8kb vocoder transmits information onthe reverse traffic channel at variable data rates

Rate Set 1 - 9600, 4800, 2400 and 1200 bps

• 13 Kbps vocoder

Rate Set 2 - 14400, 7200, 3600, 1800 bps

Reverse Traffic Channel

Reverse Traffic Channel Generation




9600 bps4800 bps2400 bps1200 bps

28.8ksps

R=1/3,K=9

1.2288McpsUser AddressMask

LongPN Code

Generator

28.8ksps Orthogonal

Modulation

Data BurstRandomizer

307.2kcps

1.2288Mcps

Q PN(no offset)

I PN(no offset)

D

1/2 PNChipDelay

Direct Sequence Spreading

ConvolutionalEncoder &Repetition

BlockInterleaver

Reverse Traffic Channel Generation

Uses Rate 1/3 Convolutional Encoder Uses 32*18 block interleaving array 64-ary Orthogonal Modulation Data burst randomizing

Data Burst Randomizing




Data Burst Randomizing

Reapted symbols are deleted

• Output stream of interleaver is gated with a time filter,During

―gate-off‖periods,transmit power is reduced

• Gate cycle varies with the transmit data rate

Randomizing transmitted data provides the effect of dispersing

in time the power received at the cell site from the mobile

stations

•Easier de-spreading can occur when fewer interfering

signals are present






• Output of the randomizer is direct sequence spread by the long code

• Each mobile station spreads its reverse traffic channel using the same

long PN code but with a different offset,which is determined by a unique42-bit mask.

• The mobile station can use one of two unique long code masks:

– A public long code mask based on the ESN

– A private long code mask

1.2288Mcps

User Address

Mask

Long

Code PNGenerator

Data BurstRandomizer

307.2kcps To Quadrature

Spreading

1.2288

Mcps

Reverse Traffic Channel Long




Reverse Traffic Channel Long

Code Mask A Reverse Traffic Channel can be spread using the“public long code mask”which is constructed as

follows:

The other option is to use a “private long code mask” based on the

current contents of the 128-bit Shared Secret Data register.

1 1 0 0 0 1 1 1 1 Permuted ESN-S

41 32 31 0

OQPSK & Baseband Filtering




OQPSK & Baseband Filtering

• The channel is spread by a pilot PN sequence with a zero offset

• Baseband filtering ensures that the waveform is contained within therequired frequency limits

• Baseband signals converted to radio frequency (RF) in the 800 MHzor 1900 MHz range

1.2288 Mcps


PN

I

Q

I

Q

cos(2pf ct)

sin(2 pf ct)PN chip

1.2288 Mcps

FromData BurstRandomizer

•

RF Converters

D

1/2 PN ChipTime Delay

BasebandFilter

Baseband

Filter

OQPSK




OQPSK

The reverse traffic channel data after direct sequencespreading is spread in quadrature by adding modulo-2.This

stream with the zero-offset I and Q PN short code sequences

is used on the forward CDMA channel.

Why a half chip delay in the Q Component?

The data spread by the Q PN short code sequence is delayed

by half a PN chip time,406.901ns,with respect to the data

spread by the I PN short code sequence. This prevents the I

and Q to change value simultaneously,thus eliminating

diagonal transitions

Reverse Channel Demodulation




Reverse Channel Demodulation

• IS-95A/J-STD-008 requires a process that is complementary to themobile station modulation process

• CDMA processing benefits from multipath components

– Signals from several receive elements can be combined toimprove receive signal quality

U/DCommand

De-InterleaverSpeechOutput

C o m b i n e r

BTS Receiver BSC

Power ControlDecision

ViterbiDecoder

Vocoder

Demodulator SearchCorrelator




PN+ tUser Long Code

Summary(1)




307.2Kbpsorthogonalmodulation

64Walsh code

1.2288McpsOrthogonal spreadfrequency,forwardchannel identification

All Forward

channel

1.2288Mcps

Orthogonal spreadfrequency for modulation

All Reverse

channel215 Short PN

19.2Kbps

1.2288McpsDirect sequence ss

MS identification

Reverse242 - 1Long PN

Code ratePurpose ApplicationLength Code sequence

Accesschannel

trafficchannel

Forward Pagingchannel

trafficchannel

Data scramble

Base stationidentification

All Reversechannel

All Forward

channel

Summary(1)

Summary(2)




Summary(2)Conception:

Convolution encoding

Code symbol repetition

Block interleaving

Data scrambling

Frame quality indicator(CRC)

Encoder tail

Data Burst randomizer

Mobile Station Call Processing States




Mobile Station Call Processing StatesDuring call processing,many messages flow between the mobile and the

base station.The mobile station may be in any of the following states:

• Mobile Station Initialization State:Pilot Channel acquisition,sync short

PN code.Receive Sync channel Message,obtains LC_STATE, SYS_TIME，

PRAT system information,implement long PN code sync

• Mobile Station Idle State:MS monitors messages on the paging channel

to receive configuration parameters from base station

• System Access State:MS sends message to the BS on the access

channel

• Mobile Station Control on the traffic channel State:MS communicates

with the base station using the forward and reverse traffic channel

CDMA MS Call Processing




Power-Up

Initialization

Idle

SystemAccess

Traffic

Mobile stationhas fully acquired

system timing

Mobile station receives a PagingChannel message requiring ACKor response, originates a call, or

performs registration

Mobile station is directedto a Traffic Channel

Mobile station ends useof the Traffic Channel

Mobile station receives an ACK toan Access Channel transmission

other than an Origination Message or a Page Response Message

Mobile station is in idle handoffwith NGHBR_CONFG equal to

‗011‘ or is unable to receive

Paging Channel Message

Contents




Contents


3.1.1 Forward CDMA Channels

3.1.2 Reverse CDMA Channels


Cdma2000 1xRTT Channel







Spreading Rates & Radio Configurations




Spreading Rates & Radio Configurations

Spreading RateIdentify the PN code rate which used for the ForwardLink or Reverse Link SR1（”1x‖，1.2288Mcps）

SR3（”3x‖，3.6864Mcps）

Radio ConfigureIdentify a serial working mode of Forward link orreverse link,each RC can support a set of data rate, the

different of each RC is diversified parameters used inchannel,such as SR and modulation performance- Forward Link:RC1～RC5- Reverse Link:RC1～RC4

Channel List: 1xRTT vs. IS-95




Channel List: 1xRTT vs. IS 95• IS-95B built on the IS-95A channels, and introduced two new channels

– Fundamental channel was the same as IS-9A traffic channel – Supplemental code channels assigned to support rates above14.4Kbps

• IS-2000 1xRTT continue to build on the IS-95 channels – IS-95 channels continue to be supported in IS-2000 to support IS-95

mobiles

Pilot channelSync channelPaging channel Access channelForward Traffic Channel Reverse Traffic Channel

Fundamental channel Fundamental channelSupplemental Code channel (F-SCCH) Supplemental Code channel (R-SCCH)

Supplemental channel (F-SCH) Supplemental channel (R-SCH)Quick Paging channel (F-QPCH) Reverse Pilot channel (R-PICH)

IS-95B

1xRTT

IS-95A

Forward Reverse

Additional Channel in 1X




Forward Quick Paging Channel(F-QPCH)

Forward Supplemental Channel(F-SCH)

Reverse Pilot Channel

Reverse Supplement Channel(R-SCH)

Additional Channel in 1X

Commercial System

Paging Channel Modes




g g C e odes Non-slotted Mode Operation

The mobile station continuously monitors the PagingChannel

Paging and control message can be received on anyslot by MS

Slotted Mode Operation MS only operates in the slotted mode when it is in the

―idle state‖

A mobile station that monitors the paging channel onlyduring certain assigned slots

The mobile station can ―sleep‖or reduce power consumption(for the power conservation) during non-active states(during the slots when the paging channelis not being monitored)

F-QPCH Functions




Q

• Base Station use F-QPCH‘s signaling to inform MS whichis surrounding of its coverage and work in slotted modeand just in idle state.

• Mobile monitors QPCH to determine if there is a pagingforthcoming on paging channel in its slot (looks at 1-bit

paging indicator)• If no flag, then mobile continues to sleep; if have flag, the

mobile monitors appropriate slot and decodes generalpage message

• Without QPCH, mobile must monitor regular pagingchannel slot and decode several fields to determinewhether page is for it or not; this drains mobile batteriesquickly

F-QPCH Functions(Cont.)




• As long as there‘s no configuration change information for the mobile to capture, the mobile‘s only going to be

monitoring 2 bits vs. an entire slot. This equates to up to40% decrease in the amount of battery power used tomonitor an IS-95 paging channel with slotted pagingimplemented.

The main purpose of QPCH is to save mobile battery life.

Q ( )

Forward Supplemental Channel (F-SCH)




pp ( )

Assigned for high-speed packet data (>9.6 kbps) in theforward direction; (FCH is always assigned to each call)

Up to 2 F-SCH can be assigned to a single mobile

SCH cannot exist without having a fundamental channel

established

SCH-1 File transfer at 144 kbps

FCH Voice, power control and link continuity

Mobile 1

Reverse Pilot Channel (R-PICH)




( )

Implement Quick Power Control onthe Forward Link

Allows base station to do timing

corrections without having to guess

where mobile is (in search window)

Mobile can transmit at lower power,

reducing interference to others

The Reverse Pilot Channel is an

unmodulated spread spectrum signal

used to assist the base station in

detecting a mobile station

transmission.

MUX A

Pilot

( all '0's)

Power Control

Bit

N is the Spreading Rate number

Pilot Power

Control

1 Power Control Group

= 1536 NPN Chips

384 NPN Chips

Reverse Supplemental Channel (R-SCH)




pp ( )

• Used for high-speed packet data (>9.6 kbps)

• Difference between F-SCH and R-SCH is in Walsh code based

spreading

– F-SCH supports Walsh code lengths of 4 to 128 (1xRTT) or 1024

(3xRTT) depending on data rate and chip rate

– R-SCH uses either a 2-digit or 4-digit Walsh code; rate matching

done by repetition of encoded and interleaved symbols

• Walsh code allocation sequence is pre-determined and

common to all mobiles

• Users are differentiated using long PN code with user mask

Benefits of the CDMA2000 1x




Increased MS standby battery life (via Quick PagingChannel)

Use Forward Quick Power Control(via Reverse Pilotchannel)

Total backward compatibility to reuse switch and callprocessing features

2-3 dB better coverage

Provides High speed 153.6 kbps packet data capabilities




IV. CDMA

KEY TECHNOLOGY

Objectives




Upon completion of this lesson, the student will beable to master:

Objectives

-- power control Identify the function of the reverse closed loop power control

Identify how to implement the Forward quick power control

-- soft handoff Identify that the handoff type when the mobile station is in

the idle state

Identify the difference between soft and softer handoff Identify the IS-95 system soft handoff processing

Identify the MS react to power control during soft handoff

Contents




C

4.1 Power Control In CDMA

4.2 Soft Handoff In CDMA

Why Power Control




CDMA is an interference-limited system based on the number of users,the interference comes mainly from nearby users

each user is a noise source on the shared channel,this creates a

practical limit to how many users a system will sustain,so CDMA

also called soft capacity limit The goal is to keep each MS at the absolute minimum power level

necessary to ensure acceptable service quality

Ideally the power received at the base station from each mobile

station should be the same(minimum signal to interference)

MS which transmit excessive power increase interference to other

Mobile station

Power Control Types




Reverse Power ControlOpen-loop Power Control

Closed-loop Power Control (Forward traffic Channel)

Outer-loop Power Control

Inner-loop Power Control

Forward Power Control

IS-95 Power Control

IS-2000 Fast Power Control (Reverse Pilot Channel)Outer-loop Power Control

Inner-loop Power Control

Reverse Open-loop Power Control




Reverse open loop power is mobile station controlling its transmit power

Reverse open loop power control consists of :

estimating how strong the mobile station should transmit based on acoarse measurement of how much power it is receiving from the basestation

some correcting parameters delivered in the access parametersmessage

The Reverse open loop method of power control provides a quickresponse to changes in signal conditions.

Mobile BTS

Reverse Open LoopPower Control

Reverse Open-loop Power Control




Problems with Reverse Open Loop Power Control – Assumes same exact path loss in both directions; therefore,

cannot account for asymmetrical path loss

– Estimates are based on total power received; therefore the powerreceived from other cell sites by mobile station introduces

inaccuracies

Reverse Closed Loop Power Control




Compensates for asymmetries between the forward and reverse paths

Consists of power up (0) & power down (1) commands sent to themobile stations, based upon their signal strength measured at theBase Station and compared to a specified threshold(setpoint)

Each command requests a 1dB increase or decrease of the mobilestation transmit power

Transmitted 800 times per second, always at full power

Allows to compensate for the effects of fast fading

Mobile BTS

Signal StrengthMeasurement

Setpoint

or

Reverse Closed LoopPower Control

Reverse Outer Loop Power Control




Most gradual form of reverse link power control

– Setpoint is varied/dynamic according to the FER on the ReverseTraffic Channel (determined at the Base Station Controller)

– Sampled at a rate of 50 frames per second (20 ms / frame)

– Setpoint adjusted every 1-2 seconds

FER

Mobile BTS BSC

Reverse OuterLoop Power

Control

Signal StrengthMeasurement

Setpoint

or

Reverse Closed LoopPower Control

The goal of outer loop power control is adjusting the setpoint(Eb/No)




g a p p s a j s g s p ( b )

based on the reverse traffic channel FER value

If the received power from the mobile station,as measured at the

base station,is below the specified S/N threshold(setpoint),the base

station sends a ―0‖power control bit directing the MS to raise its

output power;if it is higher,it sends a ―1‖ power control bit directing

the mobile station to lower its output power

The setpoint itself is raised or lowered by the reverse outer loop

power control to guarantee the desired frame error rate(FER)

level,typically 1%

Output power control bit is transmitted on the power control subchannel

in forward traffic channel

Closed-loop Power Control Procedure




Received the Frame

Quality Informationfrom the Reverse Link

Eb/Nt>Eb/No?

Outer-loop

Algorithm

Up PowerControl Bit

Down PowerControl Bit

Puncture toPower ControlSubchannel

Power ControlCommand

Measurement


Measurement

Demodulate andmeasure Eb/Nt

Outer Loop Correction

Closed-loop Control

Base Station

Mobile

Eb/No

No

Yes

Reverse Power Control in ZTE System




The open loop power control is implemented in mobile station

The outer loop power control algorithm is implemented in SVE module of

BSC, the output Eb/No is sent to Channel Card

The closed loop power control algorithm is implemented in Channel Card,

the output power control command is punctured in the forwardFundamental Channel (traffic channel).

Forward Power Control in IS-95




The base station continually and slowly decreases power to eachmobile station(each user‘s forward traffic channel)

As the FER (determined at the mobile station) increases, the mobilestation requests a Forward Traffic Channel power increase

FER

Mobile BTS BSC

Adjust Fwd.power

Forward Link Power Control

Forward Power Control in IS-95(Cont.)




The power control frequency is maximum 50Hz

Power Control based on Messages for RadioConfiguration 1

Power Control based on EIB for Radio Configuration 2

Forward Quick Power Control in IS-2000




In CDMA2000, there is afaster method used for

Forward Power Control

operating much like the IS-95

Reverse Link Power control

described next

In order to implement

Forward Link Quick Power

Control,we use Reverse Pilot

channel which includespower control subchannel

Forward Quick Power Control




Received the FrameQuality Information

from the Forward Link

Eb/Nt>Eb/No?

Outer-loopAlgorithm

Up Power

Control Bit

Down PowerControl Bit

Puncture toPower ControlSubchannel


Measurement


Measurement

Demodulate and

measure Eb/Nt

Outer Loop Correction

Closed-loop Control

Mobile Station

Base Station

Eb/No

No

Yes

Summary of Power Control




All types of power control work together to minimizes power consumptionat the mobile stations, and increases the overall capacity of the systemtransmit power.

FER FER

Mobile BTS BSC

Signal Strength

Measurement

Setpoint

or

Adjust Fwd.

power

Reverse OuterLoop Power

Control

Reverse Closed Loop

Power Control

Forward Link Power Control

Reverse Open LoopPower Control

Contents




4.1 Power Control In CDMA

4.2 Soft Handoff In CDMA

Handoff




Handoff is the process by which a mobile station maintains

communications with the Mobile Telephone Switchingcenter(MSC), when traveling from the coverage area of onebase station to that of another

Handoff keep the call established during the following

conditions: – Subscriber crosses the boundaries of a cell

– Subscriber experiences noise or other interferenceabove a specified threshold

– A base station component experiences an out-of-servicecondition during a call

CDMA Handoffs




Duringa Call

Idle Handoff

Soft Handoff

Softer Handoff

CDMA-to-CDMA Handoff

Inter-System Soft Handoff

CDMA-to-Analog Handoff

While in theIdle State

CDMA Idle Handoff




PN 104

PN 108

A

104 108

Ec/Io

Idle handoff neither softhandoff nor hard handoff.

CDMA Idle Handoff(Cont.)




PN 104

PN 108

A

104 108

Ec/Io

>3dB

CDMA Soft Handoff CDMA




Soft Handoff:The mobile station starts communications with a target basestation without interrupting communications with the current serving basestation

– Make-before-break

– Directed by the mobile not the base station,Undetectable by user

– Improves call quality

Can involve up to three cells simultaneously and use all signals

– Mobile station combines the frames from each cell

Cell SiteB

Cell SiteA

Cell SiteA

Cell SiteB

CDMA

CDMA Soft Handoff Mechanics




CDMA soft handoff is driven by the handset Handset continuously checks available pilots

Handset tells system pilots it currently sees

System assigns sectors (up to 6 max.), tells handset

Handset assigns its fingers accordingly

Each end of the link chooses what works best, on a frame-by-frame basis

Users are totally unaware of handoff

CDMA Softer Handoff




Softer Handoff is between sectors of

the same cell,that means multiplesectors of one BTS simultaneously

serve a handset

Softer handoff occurs in BTS in a

single channel element

Communications are maintained

across both sectors until the mobile

station transition has completed

MSC is aware but does not participate

All activities are managed by the cellsite

Signals received at both sectors can

be combined for improved quality

alpha

beta

gamma

CDMA-to-CDMA Hard Handoff




Between cells operating on different frequencies

Between cells that could be on the same frequency, but which aresubordinated to different MSC

A(ƒ1)

PSTN

MSC

BSC

B(ƒ2)

A

PSTN

MSC

BSC

B

MSC

BSC

T1 or E1 LinksTIA/EIA-41D

Pilot Sets




Pilot sets:the handset considers pilots in sets

– Active: Pilots of sectors actually in use (max 6 pilots) – Candidate:Pilots not currently in the Active Set, but received by the

mobile with sufficient strength to indicate that the correspondingforward traffic Channels could be successfully demodulated (max 5pilots)

– Neighbors: Pilots not currently on the Active or Candidate Sets, it toldto mobile by system,as nearby sectors to check(at least 20 pilots)

– Remaining:All other possible pilots used by the current system on thecurrent CDMA frequency,integer multiplies of PILOT_INC ,excludingthe pilot in other sets

All pilots in a set have the same frequency assignment

These sets can be updated during handoff by the base station

Rules of Soft Handoff




The MS assists the BS in the handoff process

by measuring and reporting the strengths of

received pilots using a Pilot Strength

Measurement Message

Handset sends PSMM to the system whenever:

It notices a pilot in neighbor or remaining set

exceeds T_ADD

An active set pilot drops below T_DROP for

T_TDROP time

A candidate pilot exceeds an active by

T_COMP

Pilot Strength Measurement MessageA




The Pilot Strength Measurement Message is used by the mobile station

to direct the Base Station Controller(BSC) in the handoff process.This

message uses in the Reverse Traffic Channel

A PSMM is sent to the system under one of the following conditions:

If MS finds a pilot in Neighbor or Remaining sets exceeds T_ADD

If an active set pilot drops below T_DROP after T_TDROP time

If a Candidate pilot exceeds an active pilot by T_COMP

A

B

C

Pilot Channel

Timing

Extended Handoff Direction Message




The Extended Handoff Direction Message(EHODM) is used by the

Base Station Controller(BSC) to tell the mobile station on which base

stations the BSC has allocated traffic channels for that user

An EHODM Message uses in the forward traffic channel

When the mobile station receives the EHODM message from BSC,then

it will updates its Active Set and sends a HCM to the BSC.

Pilot Search Windows




A search window is a range of PN offsets (measured in chips) where

the mobile station searches for usable multipath components of thepilots in a set

– Usable means that multipath components can be used fordemodulation of an associated forward traffic channel by MS

Search Window for pilots in the Active and Candidate

Set:

Search Window for pilots in the NeighborSet:

Search Window for pilots in the Remaining Set:

Earliest arriving usable multipath component of the pilot

pilot PN offset

pilot PN offset

SRCH_WIN_N

SRCH_WIN_A

SRCH_WIN_R

System Parameters MessageLength




MSG_TYPE (‗00000001‘)

PILOT_PN

8

9

CONFIG_MSG_SEQ 6

SID 15

NID 16

REG_ZONE 12

TOTAL_ZONES 3

ZONE_TIMER 3

MULT_SIDS 1

MULT_NIDS 1

BASE_ID 16

BASE_CLASS 4

PAGE_CHAN 3

MAX_SLOT_CYCLE_INDEX 3

HOME_REG

FOR_SID_REG

1

1

FOR_NID_REG 1

POWER_UP_REG 1

POWER_DOWN_REG 1

PARAMETER_REG 1

REG_PRD 7

BASE_LAT 22

BASE_LONG 23

REG_DIST 11

SRCH_WIN_A 4

SRCH_WIN_N 4

SRCH_WIN_R 4

NGHBR_MAX_AGE 4

PWR_REP_THRESH

PWR_REP_FRAMES

5

4

PWR_THRESH_ENABLE 1

PWR_PERIOD_ENABLE 1

PWR_REP_DELAY 5

RESCAN 1

T_ADD 6

T_DROP 6

T_COMP 4

T_TDROP 4

EXT_SYS_PARAMETER 1

EXT_NGHBR_LIST 1

GLOBAL_REDIRECT 1

RESERVED 1

Fielde gt(bits)

IS-95 Soft Handoff Signaling




Pilot Strength exceeds T_ADD

PSMM sent (request to add) ,Pilot added to Candidate Set

EHOD message received, Pilot Added to Active Set,

EHOC message sent, NLU message received

Pilot strength drops below T_DROP,Drop Timer started

Drop Timer expires

EHOD message received,Pilot Dropped into Neighbor Set, EHOC message sent,NLU message received

T_TDROP

PSMM Sent (request to remove)

IS-95 Soft Handoff Signaling(Cont.)




1.The pilot strength exceeds T_ADD.2.The mobile station sends a PSMM requesting the strong pilot added to

the active set and transfers this pilot to the candidate set.The BSC directs

the desired pilot‘s base station to allocate a forward traffic channel.

3.The current base station sends an EHODM with the new pilot included

in the ―official‖ active set list.A Walsh code is designated for the forward

traffic channel allocated on the new base station associated with the new

pilot.

The mobile station transfers the new pilot from the candidate set to the

active set.Then,the mobile station starts demodulating traffic from the newbase station and sends a handoff completion message(HCM) on the

reverse traffic channel.

IS-95 Soft Handoff Signaling(Cont.)




4.The pilot strength drops below T_DROP,and the mobile station starts thehandoff drop timer.

5.When the handoff drop timer expires,the mobile station sends a PSMMrequesting the weak pilot removed from the active set.The base station sendsan EHODM with the weak pilot removed from the ―official‖ active set list.

6.The mobile station moves the pilot from the active set to the neighborset(with the AGE counter set to zero),stops demodulating traffic associatedwith the weak pilot

7.Sends a handoff completion message on the new reverse traffic channel.The BTS sends a neighbor list update message with the composite neighbor

list compiled by the BSC.8.The mobile station updates its neighbor set.

Active vs. Candidate Set Comparison

Threshold




Threshold

t0-PSMM sent,p0>T_ADD

t1-PSMM sent,P0>p1+T_COMP*0.5dB

t2-PSMM sent,P0>P2+T_COMP*0.5dB

PSMM are triggered

not only when the

strength of a pilot from the

neighbor set exceeds the

T_ADD threshold, but

also when it exceeds the

strength of a pilot already

in the active set by

T_COMP*0.5dB

Soft Handoff Parameters




T_ADDT_DROP

T_TDROP

T_COMP

SRCH_WIN_A

SRCH_WIN_N

SRCH_WIN_R

SOFT_SLOPEADD_INTERCEPT

DROP_INTERCEPT

Soft Handoff Parameters(Cont.)SRCH WIN A

SRCH WIN A




SRCH_WIN_A

SRCH_WIN_NSRCH_WIN_R

Window size

(PN chips)

SRCH_WIN_A

SRCH_WIN_NSRCH_WIN_R

Window size

(PN chips)

0 4 8 60

1 6 9 80

2 8 10 1003 10 11 130

4 14 12 160

5 20 13 226

6 28 14 320

7 40 15 452

Soft Handoff Parameters(Cont.)T TDROP D Ti V l ( ) T TDROP D Ti V l ( )




T_TDROP Drop Timer Value(s) T_TDROP Drop Timer Value (s)

0 0 8 27

1 1 9 39

2 2 10 55

3 4 11 79

4 6 12 112

5 9 13 159

6 13 14 225

7 19 15 319

Power Control during Soft Handoff




During soft handoff, the mobile stationreceives power control bits from multiplebase stations.

If two or more power control subchannels areidentical, their power control bits are diversitycombined into one per 1.25 ms time slot.

If the mobile station receives different powercontrol bits from different power controlsubchannels, it decreases its mean poweroutput level by 1 dB.

Only if the power control bits from ALL powercontrol subchannels request a powerincrease, the mobile station increases itsmean power output level by 1 dB .




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01CDMA Theory