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Copy Rights LEGEND Co. 2010

CDMA 2000

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Introduction to Mobile Communication

Why communication systems communication systems structure

Terminals

Network

Transmission media

Why wireless History of wireless communication

Introduction to mobile systems

Multiple Access Techniques

Wireless Challenges

Cellular System Concepts

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Why communication systems

What is communication systems?

Why communication systems?

Examples of communication systems

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Communication system architecture

Structure of communication systems

Terminals (televisions , radios, phones ,..etc)

Networks (television networks , PSTN , mobile networks .etc)

Transmission media

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Why Wireless?

source DestinationTransmission medium

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Why Wireless? (cont.)

The kinds of transmission medium :1- Twisted-pair:

It is very low bandwidth and it is easily tapped either physically or bymonitoring its electromagnetic radiation

2- Coaxial cable:It is greater bandwidth than twisted-pair but it is very expensive.

3- optical fibers:

It is very high bandwidth , very high bit rate and inherently transmissionmedium.

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Why Wireless? (cont.)

Although, On a wired transmission link (copper or fiber optic), the characteristics

of the medium are very well controlled and easily predicted

It still fixed and limit the mobility of the user

While the wireless (Radio) telecommunication bridged the distances between

people who wish to Communicate while they move.

So, we will use the radio waves to transmit and receive.

But first we need to know the properties of these waves.

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History of wireless communication

18381866 Telegraphy: Morse perfects his system; Stein hill finds that the earth

can be used for a current path; commercial service is initiated

1864Maxwells equations predict electromagnetic radiation.

18871907 Wireless telegraphy :

Heinrich Hertz verifies Maxwells theory.

Demonstrations by Marconi and Popov; Marconi patents complete wireless

telegraph system (1897). 19231938 Television: Mechanical image-formation

system demonstrated; DuMont and others perfect vacuum cathode-ray tubes;field tests and experimental broadcasting begin.

1936Armstrongs paper states the case of frequency modulation (FM) radio.

1937Alec Reeves conceives pulse code modulation (PCM).

19381945Radar and microwave systems developed during World War II; FM

used extensively for military communications. 1962 Satellite communication begins with Telstar I.

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History of wireless communication (cont.)

19681969Digitalization of telephone network begins.

19701975PCM standards developed by CCITT.

19751985High-capacity optical systems developed; the breakthrough of optical

technology and fully integrated switching systems.

19801985 The first generation of modern cellular mobile networks put into

service. But it was all based on analog system:

1981 NMT-450 in Northern Europe

1983 AMPS in the United States.

1985 TACS in Europe and China

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Introduction to mobile systems

What is mobile systems

Difference between mobile systems and PSTN

The first generation of modern cellular mobile networks ( based on analog

system)

1981 NMT-450 in Northern Europe 1983 AMPS in the United States.

1985 TACS in Europe and China

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Introduction to mobile systems (2G)

1985 Standardization for second generation digital cellular systems is initialized.

1992 GSM900 in World Wide.

1993 GSM1800 in Europe.

1994 GSM1900 was firstly commercial.

Global System for Mobile (GSM)is a second-generation digital cellulartelephone system.

GSMbecame the world's leading and fastest growing mobile standard, spanning

over 174 countries, serving more than one in ten of the world's population.

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Difference between 1G and 2G mobile networks

The main difference between 1G networks and 2G networks is

1 G systems was analog but 2 G systems was digital

The analog mobile systems have main restrictions of:

the limited capacity,

voice-only services

high operational cost.

different systems are incompatible in terms of equipment and operation, e.g

NMT and TACS.

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Difference between 1G and 2G mobile networks

Capacity

While with digital systems such as GSM, the available frequency spectrum is used more efficiently, leading to

increased capacity

reductions in associated costs for network operators, equipmentsuppliers and subscribers.

Services Analog mobile systems were originally designed for voice

digital mobile systems can support voice, data and a range ofadditional services such as:

a short message service

call forwarding ISDN compatible.

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Introduction to mobile systems (2.5G)

GSM offers circuit-switched with good voice quality, but it is providing data rates

of 9.6 kbps which is too slow.

In 1999 General Packet Radio Service (GPRS)reuses the existing GSMinfrastructure to provide higher data rate

It was lunched to increase the data rate to 115 kbps by: using the packet-switched in data transmission

Defining new coding scheme.

In 2001 Evolved Data rate for GSM Evolution (EDGE)offers data rate of 384

kbps by using new modulation scheme(8psk)

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Introduction to mobile systems (North America)

In 1993 Code Division Multiple Access (CDMA)is a second-

generation digital cellular telephone system that was first deployed. CDMAOne describes a complete wireless system based on the

TIA/EIA IS-95 CDMA standard, including IS-95A and IS-95Brevisions.

IS 95A provides data rate up to 9.6Kbps/14.4Kbps

IS 95B Provides data rate up to 115.2Kbps

IS 95B is categorized as 2.5 G

CDMAOne provides a family of related services including cellularand fixed wireless (wireless local loop).

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WCDMA as a 3G Approach

The 3G solution for GSM is called WCDMA (Wideband CDMA).

WCDMA requires a new radio spectrum as it operates in ultra wide 5-MHz

radio channels.

WCDMA meets the IMT-2000 requirements of 384 kbps outdoors and 2 Mbps

indoors.

The earliest deployment was by NTT DoCoMo.

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CDMA2000 as a 3G Approach

CDMA2000 represents a family of technologies that includes:

CDMA2000 1X CDMA2000 1XEV.

CDMA2000 1X can double the voice capacity of CDMAOne networks and

delivers peak packet data speeds of 307 kbps in mobile environments.

CDMA2000 1xEV includes:

CDMA2000 1xEV-DO delivers peak data speeds of 2.4Mbps andsupports applications such as MP3 transfers and video conferencing

CDMA2000 1xEV-DV provides integrated voice and simultaneous high-

speed packet data multimedia services at speeds of up to 3.09 Mbps.

&

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Greater than 2 Mbps User Data Rate10 Different Frequency BandsCDMA Low Power (PSD) Results in:

* Low Detection Probability

*Less Susceptible to Jamming

IMT-2000

CDMA2000IS-95 W-CDMAGSM

2 Mbps Global Roaming with a single handset

3G Systems & IMT2000

Mi ti t 3G

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Migration to 3G

M lti l A T h i

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But how will we use this radio frequencies to serve all users.

Meaning of multiple access techniques

Benefits of multiple access techniques

Why we must use multiple techniques

M lti l A T h i

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Strength

f1 f2 f3Frequency

Frequency Division Multiple Access (FDMA)

M l i l A T h i

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Time Division Multiple Access (TDMA)

Strength

M lti l A T h i

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Code Division Multiple Access (CDMA).

Frequency

Strength

FDMA TDMA CDMA

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FDMA, TDMA, vs CDMA

Wi l Ch ll

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Wireless Challenges

To provide coverage for a large service area of a mobile network we

have two Options:

(A) Install one transceiver with high radio power at the center of the service

area

Drawbacks:

The mobile equipments used in this network should have high outputpower in order to be able to transmit signals across the coverage area So,

Powerful transmitters & huge equipment are required.

The usage of the radio resources would be limited, So, Capacity is limited

to the frequency band allocated.

Wireless Challenges

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Wireless Challenges

(B) Divide the service area into smaller areas (cells)

Advantages: Each cell as well as the mobile handsets will have relatively small powertransceivers.

The frequency spectrum might be reused in two far

separated cells. This yields:

1- Unlimited capacity of the system.

2- Good interference characteristics

So, The solution is going to

Cellular Systems


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The Area to be covered is divided into

small cells.So,

Low Transmission power.

Smaller equipment size.

Capacity of the system can be

increased,

Ex.: In the figure:

Capacity of one big cell =

Capacity of the band Capacity of cellular design = 7 * Capacity of one big cell.

Cellular System Concepts Frequency reuse

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Cellular System Concepts Frequency reuse

Reuse Pattern(Cluster):

Cells are grouped into Clusters

Available Band is distributed among the cells of thecluster

Each frequency is reused after the same distance D

Reuse Plan:

(D/R)= 3N N is the number of cells in a cluster .

Where R is the cell radius

5

2

3

4

7

1

6

5

N=7 Cell ClusterN=7 Cell Cluster

7 Cell Reuse Plan7 Cell Reuse Plan

2

3

4

7

1

6

5

2

3

4

7

1

6

5

2

3

4

7

1

6

5

2

3

4

7

1

6

5

D

Cellular System Concepts Sectorization

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For more efficient use of available spectrum and hence

enhancing the system capacity ,each cell is divided into

three sectors of 120o

In each sector a directional antenna is used whose

narrow beams allow reusing the channels more often

Sectorization is suitable to use in dense urban areas


Cell lar S stem Concepts Sectori ation

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Directional Antenna


Cellular System Concepts Omni Sector

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Omni Antenna

Cellular System Concepts Omni Sector

Course Outlines

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Course Outlines

Introduction to mobile communication

CDMA network architecture

CDMA network interfaces

CDMA principles Transmission problems

CDMA air interface

CDMA key technologies

Definition of Coverage Areas

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Definition of Coverage Areas

Location area

MSC area

PLMN area

Service area

Sector

area

Cell area

CDMA2000 1x network

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CDMA2000 1x network

The Base Transceiver Station (BTS)

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The Base Transceiver Station (BTS)

Consists of the radio transmitters, receivers and the antenna system required toprovide the coverage area for one cell.

Records and passes to the BSC the Signal strength measurements

Converts the CDMA radio signals into a format that can be recognized by theBSC.

Channel coding and interleaving

Spreading and despreading

Realization of diversity

Demodulation

The Base Station Controller (BSC)

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Manages the Radio Communication with the mobile station over the air

interface.

Supervises the transmission network and the operation of each BTS

The BSC is the central node within a BSS and co-ordinates the actions of

Base Stations. (i.e. The BSC controls a major part of the radio network)

BTS configuration: This involves the allocation of codes to channel

combinations and power levels for each cell according to available equipment.

Cell Description Data (e.g. cell identity, maximum and minimum output

powers in the cell).

control the power control process


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Handling of MS connections :

During Call Set Up

Paging:

Signaling set-up

Assignment of traffic channel

During a Call:

Dynamic power control in MS and BTS

Locating

The Mobile Services Switching Center (MSC)

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The Mobile Services Switching Center (MSC)

The primary node in a CDMA network is the MSC. It is the node, which

controls calls both to MSs and from MSs. The primary functions of an MSC

include the following:

Administers its Base Station Controllers BSC(s).

Switches calls to/from mobile subscribers.

Records charging and accounting details

Provides the gateway functionality to other networks.

Service provisioning.

Control of connected BSCs.

Provides the gateway functionality to other networks.

Gateway Mobile Switching Center (GMSC):

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Gateway Mobile Switching Center (GMSC):

Gateway functionality enables an MSC to interrogate a HLR in order to route amobile terminating call. It is not used in calls from MSs to any terminal other thananother MS.

For example, if a person connected to the PSTN wants to make a call to a CDMA

mobile subscriber, then the PSTN exchange will access the CDMA network byfirst connecting the call to a GMSC

Home Location Register (HLR)

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Home Location Register (HLR)

The HLR is a centralized network database that stores and manages all mobile

subscriptions belonging to a specific operator.

It acts as a permanent store for a persons subscription information until that

subscription is cancelled.

The primary functions of the HLR include:

Stores for each mobile subscriber:

Basic subscriber categories.

Supplementary services.

Current location.

Allowed/barred services.

Authentication data.

Subscription database management

Controls the routing of mobile terminated calls and SMS.

Visitor Location Register (VLR)

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Visitor Location Register (VLR)

The role of a VLR in a CDMA network is to act as a temporary storage location for

subscription information for MSs, which are within a particular MSC service area.

Thus, there is one VLR for each MSC service area. This means that the MSCdoes not

have to contact the HLR (which may be located in another country) every timethe

subscriber uses a service or changes its status.

The VLR may be integrated with the MSC.

For the duration when the MS is within one MSC service area, then the VLRcontains a

complete copy of the necessary subscription details, including the followinginformation:

Identity numbers for the subscriber Supplementary service information (e.g. Does the subscriber has call waiting

activated or not)

Activity of MS (e.g. idle or busy)

Current Location Area of MS

Short Message Center (MC or SC)

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Short Message Center (MC or SC)

As an independent entity in the CDMA cellular mobile communication system

the short message center works in coordination with other entities such as MSC

and HLR

Functions of SMC

to implement the reception, storing and transfer of the short messages fromCDMA cellular mobile communication system subscribers,

and store subscriber-related short message data.

Manages the resend of the SMS

1x Packet Data Service

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1x Packet Data Service

Compared with IS-95, in order for the CDMA2000 user data service to access, the

CDMA2000-1X core network should be added with:

PDSN,

HA (providing Mobile IP service)

AAA;

these three functional entities are the cdma2000-1X access network should

be added with PCF functional entity.

These new devices are required by the packet data service transmission to

provide high-speed access to the Internet, videophone, and e-commerce to the

users in the 3G mobile communication system.

System Architecture

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y

R-P Interface, A10/A11AAA

HA

PDSN

Firewall

BSC/PCFBTS

Billing

System

IP Network

PDSN

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As a access gateway , PDSN(packet data service node) provides the

CDMA2000 mobile station with services for Internet access or Intranetaccess. PDSN acts as an interface between Radio Network and Packet

Data Network.

Provides the mobile station with Simple IP access service or Mobile IP

access service. In Simple IP, PDSN acts as a Network access server,

while in Mobile IP, PDSN acts as Foreign Agent(FA) for Mobile Station.

At the CDMA2000 1x stage, the maximum access rate available for each

subscriber is 153.6kbps

PDSN acts as a client of AAA server.

PDSN

AAA

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AAA authenticates the script file information of the subscribers, authorizes data

services, and Collects accounting information from PDSN, completesaccounting.

Authentication

simple IP and mobile IP.

Authorizationsubscriber configuration information.

Accounting

collecting billing data(both radio specific and IP network specific) for each

packet data call.

Access Method

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Simple IP Access

- Similar to the network access through dialing-up modem on the fixedtelephone .

- Assigning dynamic IP addresses and accomplishing the data communicationwith MS as the calling party .

Mobile IP Access

- Providing a route mechanism in the internet. Assigning MS fixed addresses toconnect any sub-networks

- Accomplishing the data communication with MS as the calling party or thecalled party, and holding data communication when MS handoff betweendifferent PPP link.

AccessMethod

Parameters Involved

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Parameters Involved

In a CDMA system, the following parameters are defined to identify

a user and his location:

MIN/IMSI

MDN

ESN

SID/NID

LAI

MIN/IMSI

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Mobile subscriber identity/international mobile subscriber identity

For example, 0907550001/460030907550001

Not more than 15 digits

3 digits 2 digits

IMSI

MCC MNC MSIN

NMSI

MDN

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CC + MAC + H 0H 1H 2H 3 + ABCD

International mobile subscriber DN

National valid mobile subscriber number

Mobile directory number

For example, 8613307550001

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SID/NID

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MSCID (Exchange Identity)

= System Identity (SID) + Exchange number (SWIN)

is used to represent a certain set of equipment in an

NSS network. For example,

Unicom CDMA Shenzhen MSC is labeled as 3755+01

LAI

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LAI = Location Area Identity

PAGING message is broadcast within a local area, the size of whichdepends on traffic, paging bearer capability, signaling flow , etc.

Format: MCC+MNC+LAC

MCC: Mobile Country Code, 3 digits. For example, China is 460.

MNC: Mobile Network Code, 2 digits. For example, the MNC of Unicom

is 03.

LAC: Location Area Code, a 2-byte-long hexadecimal BCD code. 0000

cannot be used with FFFE.

For example, 460030100

Course Outlines

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CDMA principles Transmission problems

CDMA air interface


CDMA interface techniques

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What is interface?

Functions of interfaces

Why we need such technologies

To provide a high-speed, low delay multiplexing and switching network to anytype of user traffic, such as voice support, data,or video applications

Examples for switching techniques used ATM

SS7

What is ATM?

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ATM for Telecommunications is Asynch ronou s Transfer Mode,

(not Automatic Teller Machine!).

ATM is a technology that has transport, sw i tch ing, network

management, and customer services built into it right from the

start.

In general, ATM means that traffic is carried in small, fixed-

length packetscalled cells.

A technology that integrates advantages of circuit switch and

packet switch.

ATM can support any type of user services, such as voice, data,

or video service.

ATM Overview

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53byte fixed length cell= 5Bytes cell header+48Bytes

payload.

ATM must set up virtual connection before

communication.

ATM network will confer with terminal on parameter

of QoS before the connection is set up.

Contract

5-Bytes

Header

48-Bytes

Payload

ATMs Advantage

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Integration of various services such as voice, image, video, data and

multimedia.

Standardization of network structures and components. This results incost savings for network providers.

Transmission that is independent of the medium used PDH, SDH,

SONET and other media can be used to transport ATM cells.

ATM is scaleable, i.e. the bandwidth can be adapted extremely flexibly to

meet user requirements.

Guaranteed transmission quality to match the service required by the

user (quality of service, QoS).

Connectionless & Connection-oriented

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Connectionless: Every packet is

transferred from different routes, so

the receiving order of packetsdoesnt possibly depend on the

sending order.

Connection-oriented : All packets

are transferred from the same

route , so the receiving order of

packets depends on the sending

order. Time delay is fixed.

Traditional Switch Models Characteristic

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- Circuit Switching

Data is sent from the same route, so time delay is fixed

High-speed switching

Fixed rate

- Packet Switching

Support multi-rate switching

Take full advantage of bandwidth/waste of bandwidth

Time delay is not fixed

ATM Cell

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ATM Cell

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GFC ( Generic Flow Control):It is intended for control of a possible bus

system at the user interface and is not used at the moment. VPI ( Virtual Path Identifier):The VPI contains the second part of the

addressing instructions and is of higher priority than the VCI.

VCI ( Virtual Channel Identifier):VCI in each case indicates a path section

between switching centers or between the switching center and the

subscriber.

PTI ( Payload Type Identifier):Indicates the type of data in the information

field.

CLP ( Cell Loss Priority):Determines whether a cell can be preferentially

deleted or not in the case of a transmission bottleneck.

HEC ( Header Error Control):Provided in order to control and, to some

extent, correct errors in the header data that may occur. The HEC is used tosynchronize the receiver to the start of the cell.

VP and VC

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Why two fields? think VPI as a bundle of virtualchannels. (256 VPI on one link)

the individual virtual channels

have unique VCIs. The VCI values

may be reused in each virtual path.

ATM Virtual Connection

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UNI cell

VPI =1

VCI =1

UNI cell

VPI =20

VCI =30

NNI cell

VPI =26

VCI =44

NNI cell

VPI =6

VCI =44NNI cell

VPI =2

VCI =44

1

2

3

1

2

3

1

3 2

2

31

ATM Virtual Connection

Port VPI VCI

1 26 44

2 2 44

Port VPI VCI

1 2 44

2 6 44

Port VPI VCI

2 6 44

3 20 30

Port VPI VCI

1 1 1

2 26 44A B

Features of ATM

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Cells

Voice

Data

Video

Connection oriented

Fast packet switching

Statistical multiplexer

Supports voice, data and video service

Provides QoS

ATM Sublayer Model

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ATM Protocol Stack Model OSI Reference Model

User

PMD

TC

PHY

ATM

AALCS

SARInterface

manage

ment

7 Application

6 Presentation

5 Session

4 Transport

3 Network

2 Data link

1 Physical

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Function of ATM Layer

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Cell switch

Quality of Service

Processing the cell header

Types of payload

Multiplexing /Demultiplexing of different

connection cell

AAL

ATM

PHY

Function of AAL layer

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Support services for user

Segment and reassemble

Complete the change between User-

PDU and ATM payload

AAL

ATM

PHY

Function of ATM AAL Overview

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Function of ATM AAL:

Provide a high-speed,

low delay multiplexing

and switching network

to support any type of

user service, such as

voice, data, or video

applications.

ATM Payload

ConstantBit Rate DataBursts VariableBit Rate

ATM Cell

Multiplexing

AAL SDU

TCP/IP Process

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App DataTCP Header

TCP header App DataIP Header

IP Header TCP Header App DataLLC

SAR-SDU#1 SAR-SDU#2 SAR-SDU#3 SAR-PDU#4 SAR-PDU#5

TCP

IP

SNAP/LLC

AAL5

CS

SAR

ATM

PHY

Cell header will be added to SAR-PDU, whose VPI and VCI depends on

the map table of IP address to PVC/SVC. Then ,the cells will be sent to

Physical Layer.

Perform the transmission of ATM cells via physical media.

LLC IP Header TCP Header App Data PAD CPCS-PDU Tail

INARP in IPOAPVC Mode

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Terminal A IP:192 .168 .1 .1

ATM Network

Terminal B IP:192 .168 .1 .2

PVC

*Any IPOA terminal that wants to communicate with other terminal must know

the destination IP address. But how to know the IP address? PVC connecting

the source and destination terminals should be set up first. For example:

Terminal A must set up a PVC to B in order to know the IP address of B.

Network Interfaces

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Main interfaces1- Um interface (air interface)

It is defined as the communication interface between MS and BTS

It is physical linking is realized through radio link

2- A interface

It is defined as the communication Interface between NSS and BSS (MSC

and BSC) It is physical liking is realized using standard 2.04 Mbit/s (E1) PCM digital

transmission link

Network Interfaces

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Network subsystem Interface

1- B interface: It is defined between VLR ad MSC

It is used by MSC to ask VLR for information about the location of MS, or

to update MS location

2- C interface

It is defined between HLR and MSC It is used for route selection and management information (billing)

Network Interfaces

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Network subsystem Interface

3- D interface It is defined between HLR and VLR

It is used for exchanging the information about MS location and

Subscriber management

The VLR is integrated with MSC and HLR is integrated with AC. So, the

physical linking of D-interface is realizing through the standard 2.048

Mbits/s

4 - E interface

It is defined as the interface among different MSCs of controlling adjacent

areas [Handoff]

it is physical linking is realized through the standard 2.048 Mbits/s PCM

digital transmission link.

Course Outlines

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CDMA principles

Transmission problems

CDMA air interface


Multiple Access Technologies

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User 1 User 2 User 3

Time

Frequency

FDMA

User 1

User 2

User 3

Time

Frequency

TDMA

Time

Frequency

CodeCDMA

User3

User2

User1

Based on codes, all users obtain traffic

channels at the same time and on the samefrequency band, for example, WCDMA and

CDMA2000

Traffic channels on different frequency bands are

allocated to different users, for example, AMPSand TACS

Traffic channels at different points of time areallocated to different users, for example, DAMPS and

GSM

Advantages of CDMA

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Advantages of CDMA

The coverage radius is 2 times of standardGSM.

Coverage of 1000 km2: GSM needs 200

BTS's, while CDMA requires only 50.

Under the same coverage conditions, the

number of BTS 's is greatly decreased

SimpleNetworkPlanning

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Simple project design &

convenient capacity expansion

1

3

2

4

3

2

4

2

4

4

1

2

3

1

4

2

3

1

4

GSM: N=4Frequency reuse

1

1

1

1

1

1 1

1

1

1

1

1

1

1

1

1

1 1

1

1

1

1

CDMA: N=1

Frequency reuse

Green Handset

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SystemsMean

transmissionpower

Max transmissionpower

GSM 125 mW 2W

CDMA 2 mW 200mW

Low transmission power:

Accurate power control, handoff

control, voice activation

HighQualityVoice(1)

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Voice quality

64kPCM

presentGSM

8kCDMA

13kCDMA

8k EVRC

CDMA

CDMA principles

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CDMA principles

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CDMA principles

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CDMA Principals

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SHANNONS CAPACITY EQUATION

C = Bw log2[ 1 + S/N ]

Bw= bandwidth of the signal in Hertz

C= channel capacity in bits/second

S= signal power

N= noise power

Spread Spectrum

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By a small amount of analysis in Shannon equation we can see that the:

bandwid th of the sign al (Bw ) is inversely p ropor t ional to the sign al power

This result can be used to serve more than one user by the same frequency in thesame time by generating a new dimension to discriminate between the different

users and make the spreading process So, the question is how to make the spreading process

f

Sf

The spectrum before spreading

information

f0

The spectrum after spreading

information

f0

Sf

f

Two Types of Spread Spectrum

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Direct Sequence narrowband input from a user is coded (spread) by a user-unique

broadband code, then transmitted broadband signal is received; receiver knows, applies users code,

recovers users data

Direct Sequence Spread Spectrum (DSSS) CDMA IS the method used in

IS-95 commercial systems

DSSS Spreading: Time-Domain View

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At Originating Site:Input A: Users Data @ 19,200 bits/second

Input B: Walsh Code #23@ 1.2288 Mcps

Output: Spread spectrum signal

via air interface

At Destination Site:Input A: Received spread spectrum signal

Input B: Walsh Code #23 @ 1.2288 Mcps

Output: Users Data @ 19,200 bits/second justas originally sent

DSSS Spreading: Frequency-DomainView

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information pulse interference White noise

The improvement of

time-domain

informationrate means

that the bandwidth of

spectrum-domain

information is spread.

The Y-coordinate is energy density.

The spectrum before despreading

informationInterference noise

Sf

f0 ff0

The spectrum after despreading

information

Interference noise

Sf

f

f

Sf

The spectrum before spreading

information

f0The spectrum after spreading

information

f0

Sf

f

Spread Spectrum

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Processing Gain (CDMA Spreading Gain)

Processing gain is the ratio of a spreading rate to a data rate.

Consider a user with a 9600 bps vocoder talking on a CDMA signal1,228,800 Hz wide.

So, the processing gain is 1,228,800/9600 = 128.

The processing gain in IS-95 system is 128, about 21dB.

The processing gain is calculated as follows:

10 x log10

128 = 21db

Spread Spectrum

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Principle of Using Multiple Codes Using several multiple codes improves the system because they are

independent

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 StreamsORIGINATINGSITE DESTINATION

Advantages of Spread Spectrum

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Give the ability of multiple access

Avoid interference arising from jamming signal or multi-path effects.

Covert operation: Difficult to detect

Achieve Privacy: Difficult to demodulate, (Noise like signal.)

Impossible to Eavesdrops on the signal expect using the same code

Definitions

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Forward link: the direction from a base station to a mobile station

Reverse link: the direction from a mobile station to a base station

CDMA channel: Code Channels are characterized (made unique) by

mathematical codes (stream of 1s and 0s)

45 or 80 MHz

CDMACHANNELCDMA

ReverseChannel 1.25 MHz

CDMAForward

Channel 1.25 MHz

Walsh Code

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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 arefiltered out in the process

In forward direction, each symbol is spread with Walsh code

Walsh codeis used to distinguish the user in forward link

For IS95A/B, in the reverse, every 6 symbols correspond to one Walsh code.For example, if the symbol input is 110011,the output after spreading is

W5164 (110011=51).

For CDMA2000, in the reverse, Walshfunction is used to define the type of

channel (RC 3-9)

Walsh Code

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W2n=Wn Wn

Wn Wn

W1=0

W2=0 0

0 1

W4=

0 0 0 00 1 0 1

0 0 1 1

0 1 1 0

Walsh code

How to generate Walsh code?

Its simple to generate the codes, or theyre small enough to use from ROM

Wimrepresents ith(row) Walsh function of length m.

For example, W24is 0101 in the Matrix W4

Walsh Code

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Two same-length binary strings are orthogonal if the result of XORing them has

the same number of 0s as 1s

M- sequence

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In CDMA system, user information is encrypted by means of scrambling. The

scramble code used here is M-sequence.

Shown in the figure is an M-sequencegenerator made up of a shifting registersequence with certain feed bake.

The period of the output sequence is 2N-1(N being the number of shifting

registers). That is to say, the shifting register sequence resumes to the initial

status when every 2N-1pieces of codes are output.

0 0 10 0 1

Short code

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The short codeis a binary M-sequence with 15 shift register.

Short codeis PN sequence with period of 215- 1chips

Sequence with different time offsets are used to distinguish different

sectors

Minimum PN sequence offset used is 64 chips, that is to say, 512PN offsets

are available to identify the CDMA sectors (215/64=512).

the two sequences scramble the information on the I and Q phase channels

PNa

PNc

PNb

Long code

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The long codeis a PN sequence with a period of 242-1chips

Each mobile station uses a unique User Long Code Sequence generated by:

Long Code State Registermakes long code at system reference timing, tothe 42-bit

A Mask Registerholds a user-specific unique pattern of bits (32-bit ESN+10-bit for operator)

Each clock pulse drives the Long Code State Register to its next state

State register and Mask register contents are added in the Summer

Summer contents are modulo-2 added to produce just a single bit output

The output bits are the Long Code, but shifted to the users unique offset

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

Long code

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Out

0 0 1

1 1 0

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

Coding Process on CDMA Forward Channels

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WALSH

19

BTSPilot Walsh 0

Walsh 19

Paging Walsh 1

Walsh 6

Walsh 11

Walsh 20

Sync Walsh 32

Walsh 42

Walsh 37

Walsh 41

Walsh 56

Walsh 60

Walsh 55

PN OFFSET 116BTS

PN OFFSET 226BTS

PN OFFSET 510BTS

SPN

372

x

x

x

PN OFFSET

ANALOGSUM/MUX

PN OFFSET 372

Course Outlines

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CDMA principles


CDMA air interface


Effects on Radio Communication

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Signal degradation can be classified by type :

Path Loss

During distance covered by the radio signal, it is called Free space

path loss , it can be calculated by LFS = 32.44 + 20 log F (MHz) +

20 log d (Km)

Signal attenuation

Resulting from shadowing effects introduced by the obstacles betweentransmitter and receiver

Fading of the signal

Caused by numerous effects all of which are related to the Radio

propagation phenomenon


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the Radio propagation phenomenon Reflection

Propagating wave impinges on an object which is large compared towavelength

E.g., the surface of the Earth, buildings, walls, etc.

Diffraction

Radio path between transmitter and receiver obstructed by surface with

sharp irregular edge Waves bend around the obstacle, even when LOS does not exist

Scattering

Objects smaller than the wavelength of the propagating wave

E.g., foliage, street signs, lamp posts

Fading Problems

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1. Shadowing (Normal fading):

The reason for shadowing is the presence of obstacles like large hills or

buildings in the path between the site and the mobile. The signal strength received fluctuates around a mean value while changing

the mobile position resulting in undesirable beats in the speech signal.

2. Rayleigh Fading (Multi-path Fading):

The received signal is coming from different paths due to a series of

reflection on many obstacles. The difference in paths leads to a difference inpaths of the received components.


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Fading Problems

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Fading Problems Solutions

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1. Increase the fading Margin


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2. Antenna diversity (Space Diversity)

The cell transceiver will use two receiving antennasinstead of one. They

will be separated by a distance of about (10* ), and they will receive radiosignals independently, so they will be affected differently by the fading dips

and the better signal received will then be selected.

Received Signal Strength

Distance


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Space diversity

That means we can use two antennas for receiving instead of one

antenna to avoid the fading of the signal at a certain receiving point

The RAKE Receivers

To avoid the multi-path effect there are several RAKE Receivers in

the mobile station and the base station where the signals whicharrives at mobile station at different time will be demodulated

separately and will be given a different time delay so as to keep them

in phase and the Mobile station will perform vector adding of these

signals

Rake Receiver

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d1d2

t t t

d3

transmission receivingRaker combination

noise

The Principle of RAKE Receiver

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The RAKE technology can overcome the multi-path fading and enhance

the receive performance of the system.

Receive set

Correlator 1

Correlator 2

Correlator 3

Searcher correlatorCalculate the

time delay and

signal strength

Combiner The combined

signal

tt

s(t) s(t)

Course Outlines

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CDMA principles


CDMA air interface


CDMA air interface

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What is air interface

Defines the technology between MS and BTS

Carries most of the characteristics of the mobile systems features

Determines the capacity and quality of the system

RNP and RNO depends mainly on air interface parameters

CDMA frequency assignment

Band Class li kMH D li kMH

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Band Class uplinkMHz DownlinkMHz

0 824849 869894

1 18501910 19301990

2 872915 917960

3 832870 887925

4 17501780 18401870

5 412460 420493

6 19201980 21102170

7 746764 776794

5

CDMA frequency assignment

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There are 8 band classes stipulated in the IS-2000 for the working

frequency band of the CDMA2000:

1. Band Class0: Corresponding to the North America cellular

frequency band, also in use in China, Hong Kong,

Australia, North Korea and Taiwan.

2. Band Class1: Corresponding to the PCS frequency band in North

America.

3. Band Class2: Corresponding to the TACS frequency band.

4. Band Class3: Corresponding to the JTACS frequency band.

5. Band Class4: Corresponding to the PCS frequency band in South

Korea.

6. Band Class5: Corresponding to the NMT-450 frequency band.

(Nordic Mobile Telephone)

7. Band Class6: Corresponding to the IMT-2000 frequency band.8. Band Class7: Corresponding to the 700MHz cellular frequency

band in North America.

General CDMA System Model

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Information stream (transmission)

Interleaving

Source

decoding

deinterleaving

Source

codingInterleaving

deinterleaving

Scrambling

Unscrambling

Spreading

Despreading

Modulation

Demodulation

Radio

frequency

transmitting

Radio

frequency

receive

Information stream (reception)

channel

coding

channel

decoding

Analog to Digital converter

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In CDMA system the signal is sampled by 8KHZ(or 8 K sample per second) with

each sample using 13 bits with linear quantization, which gives an input data rateof 104 Kbps.

Then it is broken into 20msframes.

But because the air resource in a wireless system is very precious, a more

effective coding mode is needed to use a rate as low as possible in the casewhere voice quality is guaranteed which is the function of source coding.

Source Coding

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Source Coding in CDMA is done by Vocoder

vocoder is such a device the main principles of it are to extract some voice feature

parameters when a person speaks and transmit these feature parameters to thepeer party. Then, the peer party will recover the voice with these parameters

based on the promise between the two parties.

Meanwhile, the codes transmitted from the transmit end to the receive end and

describing voice feature parameters vary with:

speech activity total bit error rate.

Source Coding

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Where this Vocoder has two rates:

8K QCELP(Rate Set 1: 9600, 4800, 2400 and 120 bps)

13K QCELP(Rate Set 2: 14400, 7200, 3600 and 1800 bps)

The third voice code is the Extended Variable Rate Coder (EVRC)which has

a full rate output of 8Kbps in QCELP but has voce quality very closer to the

13Kbps in QCELP

Channel Encoding

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Convolutional code or TURBO code is used while a channel is encoded

Constraint length = shift register number+1.

Encoding efficiency = the input bits number / the output symbols number.

Convolutional encoder

It b f th fi th t th d t d b i t

Interleaving

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The direction of the data stream

1 2 873 64 5

1 2 873 64 5

1 2 873 64 5

1 2 873 64 5

1 2 873 64 5

1 2 873 64 5

1 2 873 64 51 2 873 64 51 2 873 64 5

1 2 873 64 5

1 1 111 11 1

2 2 222 22 2

7 7 777 77 7

6 6 666 66 6

3 3 333 33 3

4 4 444 44 4

1 2 873 64 51 2 873 64 55 5 555 55 5

8 8 888 88 8

interleaving

It can be seen from the figure that the data are read row by row into an

interleaverat the transmit end, read column by column out (this process

is called interleaving) and propagated after other modulation process.

Then, the data enter the interleaverat the receive end row by row and

are read out column by column (this process is called de-interleaving)

Spreading

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6 Symbols 6464matrix

64iw

( )2012345 DDDDDDi= 0101..01

Walsh function of order 64

The forward channel is channelized by a Walsh code and the reverse channelby a long code.

In the reverse, every 6 bits from the encoder output corresponds to one

Walsh code.That is to say, every 6 symbols are spread into 64 chips.

In the forward, each bit from the encoder output corresponds to a Walsh

code.That is to say,each symbol is spread into 64 chips.

Modulation

Th f d h l d l t d b f QPSK

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OQPSK

QPSK

The forward channel modulated by means of QPSK.

The reverse channel by means of OQPSKcan reduce the fluctuation range

of modulated signals.

For OQPSKAs opposed to the data modulated by I pilot PN sequence, thedata modulated by Q pilot PN sequence has the delay of half a PN chip(406.901ns).

Thus, the maximum phase change of four-phase modulation is 90 degreesinstead of 180-degree mutation.

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Types of Channel in IS-95A

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Forward channel

Forward Pilot Channel

Forward Sync Channel

Forward Paging Channel

Forward Traffic Channel (including power control subchannel)

Reverse channel Access Channel

Reverse Traffic Channel

Pilot Channel

Used by the mobile station for initial system acquisition

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Used by the mobile station for initial system acquisition

Transmitted constantly by the base station

The same Short PN sequences are shared by all base stations

Each base station is differentiated by a phase offset of 64 bits

Provides tracking of:

Timing reference

Phase reference

Separation by phase provides for extremely high reuse within one CDMA

channel frequency Acquisition by mobile stations by using :

Short duration of Pilot PN sequence

Uuencoded nature of pilot signal

Facilitates mobile station-assisted handoffs

Used to identify handoff candidates

Key factor in performing soft handoffs

Pilot Channel Generation

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The Walsh function zero spreading sequence is applied to the Pilot

The use of short PN sequence offsets allows for up to 512 (215/64) distinct Pilotsper CDMA channel ( frequency carrier)

The PN offset index value (0-511 inclusive) for a given pilot PN sequence ismultiplied 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 delayed

960 chips x 0.8138 microseconds per chip = 781.25 microsecond

Pilot

Channel

(All 0s)

1.2288Mcps

I PN

Q PN

Walsh

Function 0

Pilot Channel Acquisition procedure

Pilot Channel

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What is pilot acquisition?

Pilot Channel Acquisition procedure

The mobile station starts generating the I and Q PN short sequences by itself

and correlating them with the received composite signal at every possibleoffset.

In less than 15 seconds (typically 2 to 4 seconds) all possibilities (32,768) arechecked.

The mobile station remembers the offsets for which it gets the best correlation(where the Eb/N0is the best.)

The mobile station locks on the best pilot (at the offset that results in the bestEb/N0), and identifies the pattern for defining the start of the short sequences

Now the mobile station is ready to start de-correlating the SYNCH channelwith a Walsh code.

0001 0001 0001 0001 0001 0001

Pilot Channel(Walsh Code 0)

Sync Channel

Used to provide essential system parameters

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Used to provide essential system parameters

It used Walsh function number 32

Used during system acquisition stage

Bit rate is 1200 bps Simplifies the acquisition of the Sync Channel once the Pilot

Channel has been acquired

Mobile Station re-synchronizes at the end of every call

Now the mobile enters the idle state

(Acquired Pilot)

Sync Channel

Sync. Message Parameters

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System ID(SID)16-bit unsigned integer identifying the system

Network ID(NID)16-bit unsigned integer identifying the network

within the system (defined by the owner of the SID)

Pilot PN Sequence OffsetIndex (PILOT_PN)Set to the pilot PN

offset for the base station (in units of 64 chips), assigned by the

network planner

Long Code State(LC_STATE)Provides the mobile station with

the base station long code state at the time given by the SYS_TIMEfield, generated dynamically

Sync. Message Parameters

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System Time (SYS_TIME)GPS system-wide time as 320 ms after the end of

the last superframe containing any part of this message, minus the pilot PN offset,in units of 80 ms, generated dynamically

Paging Channel Data Rate(PRAT)The data rate of the paging channel for thissystem, determined by the network planner

00if 9600 bps

01if 4800 bps

CDMA Frequency Assignment(CDMA_FREQ)

Sync Channel Generation

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1200 bps

Walsh Function 32

1.2288 Mcps

IPN

ConvolutionalEncoder and

RepetitionBlock

Interleaver

R = 1/2 K=9

Modulation

Symbols

4800 sps 4800 sps

Bits Chips

QPN

Paging Channels

The Paging Channel ses Walsh f nction 1

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The Paging Channel uses Walsh function 1

Two rates are supported: 9600 and 4800 bps

The paging channel message:

System parameters message

Access parameters message

Neighbors list message

CDMA channels list message

The functions of a paging channel:

Paging mobile stations and responding access channels Assigning traffic channel

Paging Channels Generation

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9600 bps

4800 bps

Walsh

function

1.2288

Mcps

Q PN

1.2288

Mcps

19.2

Ksps

19.2

KspsPaging Channel

Address Mask

R = 1/2 K=9

Decimator

Convolutional

Encoder &

Repetition

I PN

Block

Interleaving

Scrambling

Long PN Code

Generator

CDMA Forward Traffic Channel

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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 - 7 Paging channel.

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

Unused paging channels can provide up to 6 additional channels.

Now we will talk about the generation of the traffic channel procedure indetails

Forward Traffic Channel

8 kb Vocoding Generation

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8 kb Vocoding Generation

Walsh

function

Power

Control

Bit

I PN

9600bps

4800 bps

2400 bps

1200 bps

(Vocoder) ConvolutionalEncoding and

Repetition

1.2288

McpsLong PN CodeGeneration

800Hz

R=1/2,K=9

Q PN

Decimator DecimatorUserAddressMask

(ESN-based)

19.2

ksps

1.2288

McpsScrambling

bits symbols chips

19.2

ksps

CHANNEL ELEMENT

M

U

X

BlockInterleaving

Rate 1/2, k=9 Convolutional Encoding

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Symbols generated as the information bits transit through the encoder, are

related to all the bits currently in the register.

Each information bit contributes to multiple symbols.

Pattern of inter-relationships helps detect and correct errors.

The length of shift register is called constraint (K=9) length. The longer the register, the better coding can correct bursty errors

Here, two symbols are generated for every bit input (Rate 1/2).

Full Rate Block Interleave

Symbols are

Written In

16 Columns

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The 384 modulation symbols in a frame are input into a 24 by 16 block interleave array and read down

by columns, from left to right

Adjacent symbols are now separated in time This separation combats the effect of fast fading

A burst of errors could effect the area in red above and after the frame is written into the block de-

interleave function at the mobile we see the errors are spread out instead of being in consecutive order.

Written In

Symbols are

Read Out

1 25 49 73 97 121 145 169 193 217 241 265 289 313 337 361

2 26 50 74 98 122 146 170 194 218 242 266 290 314 338 362

3 27 51 75 99 123 147 171 195 219 243 267 291 315 339 363

4 28 52 76 100 124 148 172 196 220 244 268 292 316 340 364

5 29 53 77 101 125 149 173 197 221 245 269 293 317 341 365

6 30 54 78 102 126 150 174 198 222 246 270 294 318 342 3667 31 55 79 103 127 151 175 199 223 247 271 295 319 343 367

8 32 56 80 104 128 152 176 200 224 248 272 296 320 344 368

9 33 57 81 105 129 153 177 201 225 249 273 297 321 345 369

10 34 58 82 106 130 154 178 202 226 250 274 298 322 346 370

11 35 59 83 107 131 155 179 203 227 251 275 299 323 347 371

12 36 60 84 108 132 156 180 204 228 252 276 300 324 348 372

13 37 61 85 109 133 157 181 205 229 253 277 301 325 349 373

14 38 62 86 110 134 158 182 206 230 254 278 302 326 350 374

15 39 63 87 111 135 159 183 207 231 255 279 303 327 351 375

16 40 64 88 112 136 160 184 208 232 256 280 304 328 352 376

17 41 65 89 113 137 161 185 209 233 257 281 305 329 353 377

18 42 66 90 114 138 162 186 210 234 258 282 306 330 354 378

19 43 67 91 115 139 163 187 211 235 259 283 307 331 355 379

20 44 68 92 116 140 164 188 212 236 260 284 308 332 356 380

21 45 69 93 117 141 165 189 213 237 261 285 309 333 357 381

22 46 70 94 118 142 166 190 214 238 262 286 310 334 358 382

23 47 71 95 119 143 167 191 215 239 263 287 311 335 359 383

24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384

24Rows

Data Scrambling

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Every 64thPN chip is modulo-2 added to a symbol

Randomize transmitted data

Effects of all 1s or 0s' traffic (impulse-like) is reduced as the stream of

ones or zeros will cause that the receiver may loss the synchronizationwith the transmitter as there is any changes in transmitted data

Eliminates probability of Pilot Reuse Error

Mobile might demodulate a distant cell with same PN offset

Block

Interleaver

Long

Code PN

Generator

19.2 Ksps

ModulationSymbols

User Address

Mask (ESN)Decimator

Divideby 64

19.2Ksps

1.2288Mcps

19.2Ksps

To Power

Control Mux

Power Control Sub-channel

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A power control sub-channelis transmitted continuously every 1.25ms (or800HZ)

BTS instruct MS to change its power level by +1dB. A 0 power control bitrequests the MS to increase its power. A 1 power control bit instruct the MS

to decrease its power Each power control bit has a bit time of two of data bit (for Rate set 1)

A puncturing technique: The 1/(64*24) long code is used to randomize theposition of the power control bit

19.2 Kspsfrom Block

Interleaver

1.2288 Mcps

User Long

CodeDecimator

Scrambled

ModulationSymbol orPowerControl Bit19.2

Ksps

Decimator

Data Scrambling

MU

X

800 bpS MuxTiming

Power ControlBit (800 bps)

Composite I and Q

WalshIPN Code

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Each channel card has a combiner andworks in a serial array to combine the I

and Q signals for all forward channelsin a partition sector or cell.

The base band I and Q signals for allchannel cards are sent to the COREmodule to be multiplexed togetherbased on the PN offset.

This ensures that a mobile station doesnot mistakenly decode the signal from achannel with the same Walsh code fromthe wrong base station.

Pilot

Channel

Walsh

Code

Sync

Channel

Walsh

Code

Paging

Channel(s)

WalshCode

Forward TrafficChannel(s)

Walsh

Code

QPN Code

Composite

I

Composite

Q

Quadrature Phase Shift Key (QPSK) Modulation

I PN Code

cos (2pfct)

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QPSK output = Icos (2 fct) + Q sin (2 fct)

: XOR

S: Analog sum

: Base band x Carrier

Every

Channel

Walshcode

Q PN CodeI PN Code

Base bandfilter

Base bandfilter

( c )

sin (2pfct)

S

S

S

GainControl

Reverse Traffic Channels

Used when a call is in progress to send:

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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:

8 Kbps vocoder

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

13 Kbps vocoder

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

Reverse Traffic Channels

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9600 bps4800 bps2400 bps1200 bps

28.8ksps

R=1/3,K=9

1.2288Mcps

User 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

DirectSequenceSpreading

Convolutional

Encoder &

Repetition

Block

Interleaver

Rate 1/3 Convolutional Encoder

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+

+

+

g0

g1

g2

Information bits

(INPUT)

Code Symbols

(OUTPUT)

Code Symbols

(OUTPUT)

Code Symbols(OUTPUT)

1 2 3 4 5 6 7 8

Block Interleaving

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28.8 ksps

From Coding

& SymbolRepetition

28.8 ksps to

Orthogonal

ModulationInput Array

(Normal

Sequence)

32 x 18

Output Array(Reordered

Sequence)

32 x 18

The 576 modulation symbols in a frame are input into a 32 by 18 block

interleave array read down by columns, from left to right

64-ary Orthogonal Modulation

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For every six symbols in, 64 Walsh Chips are output

Six symbols are converted to a decimal number from 0-63

The Walsh code that corresponds to the decimal number becomes the output

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

Symbols

3544 Walsh Lookup TableWalshChipwithin aWal shFunction

0 1 2 3 4 5 6 7

11

8901

1111

2345

1111

6789

2222

0123

2222

4567

2233

8901

3333

2345

3333

6789

4444

0123

4444

4567

4455

8901

5555

2345

5555

6789

6666

0123

0

1

23

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

0000

0101

00110110

4

5

6

7

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

8

9

10

11

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

12

13

14

15

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

Wals

16

17

18

19

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

h

Fu

20

21

22

23

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

nc

ti

24

25

26

27

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

on

I

28

29

30

31

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

ndex

32

33

34

35

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

36

37

38

39

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

40

41

42

43

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

44

45

46

47

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

48

49

50

51

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

52

53

54

55

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

0000

0101

0011

0110

1111

1010

1100

1001

56

57

58

59

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

0000

0101

0011

0110

1111

1010

1100

1001

1111

1010

1100

1001

6061

62

63

00000101

0011

0110

11111010

1100

1001

11111010

1100

1001

00000101

0011

0110

11111010

1100

1001

00000101

0011

0110

00000101

0011

0110

11111010

1100

1001

11111010

1100

1001

00000101

0011

0110

00000101

0011

0110

11111010

1100

1001

00000101

0011

0110

11111010

1100

1001

11111010

1100

1001

00000101

0011

01101 0 0 0 1 . . . 1 1 0 1 0

64 Chip Pattern ofWalsh Code # 35

Direct Sequence Spreading

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

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 AddressMask

LongCode PN

Generator

Data BurstRandomizer

307.2

kcpsTo QuadratureSpreading

1.2288Mcps

Offset Quadrature Spreading & Baseband Filtering

RF Converters

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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 MHz or1900 MHz range

1.2288

Mcps

I-Channel Pilot PN Sequence

1.2288 Mcps

PN

I

Q

I

Q

cos(

2

pfct)

sin(2 fct)PN chip

1.2288

Mcps

From

Data Burst

Randomizer

RF Converters

D

1/2 PN Chip

Time Delay

Baseband

Filter

Baseband

Filter

Cos(2fct)

sin(2fct)

Access Channels

Used by the mobile station to:

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y

Initiate communication with the base station

Respond to Paging Channel messages

Has a fixed data rate of 4800 bps

Each Access Channel is associated with only one Paging Channel

Up to 32 access channels (0-31) are supported per Paging Channel

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)

Access Channel Generation

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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

Block

Interleaver

Access Channel

Information

(88 bits/Frame)

4.8 kpbs

DirectSequence

Spreading

Summarization of Initialization of the Mobile Station

Search for the CDMA carrier acquire the pilot channel and synchronize the short

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Search for the CDMA carrier, acquire the pilot channel and synchronize the short

code.

Receive the synchronous channel message containing the LC_STATE,

SYS_TIME, P_RAT.

Acquire timing and synchronize with the system.

Monitor the paging channel and receive the system message.

The mobile station can register and be taken as the calling party or called party.

Difference between IS95A and IS-95B

What is IS95B?

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IS-95B is based on and compatible completely with IS-95A.

The main difference :

Increase the supplemental code channels to enhance the data rate. A

single user can be assigned less than 8 code channels (1 FCH + 7

SCCH)the highest data rate being 76.8 (rate set 1) / 115.2kbps (rate

set 2).

Soft handoff with relative thresholds

MS-aided hard handoff

Overview of CDMA 1X

Channel bandwidth:

1 23MH

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Completely compatible IS-9

Date post:	03-Jun-2018
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