CDMA-ARCHITECTURE

7/28/2019 CDMA-ARCHITECTURE

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Architecture of CDMA

WLL System


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Main components of CDMA System

MSS (Mobile Switching Sub-system)

BSS(Base Station Sub-system)

MS(Mobile Station)

OMC (Operation and Maintenance Center)


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CDMA switching function

Manages mobile subscriber data

Manages database for mobile service

Interfaces between CDMA network and other network

(such as PSTN, other PLMN etc.).

It includes 4 function units:

---MSC ---VLR

---HLR ---AUC

Mobile Switching Sub-system


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Mobile Switching Center(MSC)

It is responsible for setting up, managing and clearing connections

as well as routing the calls to the proper user.

It provides the network interfaces, the charging function and the

function of processing the signaling.

MSC gets data for call handling from 3 databases: VLR/HLR/AUC

.


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Visitor Location Register(VLR)

VLRis a dynamic database used by MSC for information

index. It stores all related information of mobile subscribers

that enter its coverage area, which enables MSC to set up

incoming and outgoing calls.

Subscriber parameters include: subscriber number,

location area identity(LAI), users status, services which

subscriber can use and so on.

When the subscriber leaves this area, it should register in

another VLR, and the previous VLR will delete all the dataabout this subscriber.

VLR can be built together with the MSC or set separately.


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HLR:It is a static database. When a user apply for mobile service, all

data about this subscriber will be stored in HLR.

Information:

Subscriber information (ESN, MDN, IMSI, MIN), service

information and valid term.

The mobile subscriber location (MSC/VLR address), so as to set upthe call route to the MS.

HLR can be built together with the MSC or set separately.

Home Location Register(HLR)


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Authentication Center

It is an entity to prevent illegal subscribers from

accessing CDMA network. It can generate theparameter to confirm the subscribers identity.

At the same time it can encrypt users data

according to users request.


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Operation and Maintenance Center (OMC)

OMC provides operation and maintenance services to the

network operator, manages the registered subscriber information

and conducts network planning to enhance the overall workingefficiency and service quality of the system.

Based on the main maintenance functions, there are two types of

operation and maintenance centers: OMC-S and OMC-R. The

OMC-S is mainly responsible for maintenance of MSS while the

OMC-R is mainly for BSS.

OMC is also known as background.


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Base Station Sub-system

It provides trunks between wireless part and fixed part of

PLMN network.

---BSC

BSC performs the controlling function and management.

---BTS

BTS is in charge of wireless transmission.


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Um EAbis A

Q C

B

N H

MS

BTS

BSC

PSTNMSC

M S

C

VLR

HLR AUCMC

D

MCM

MSS

BSS

Ai

Architecture of CDMA system


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Um interface defines the communication interface between MS and

BTS, also called air interface.

It realizes the compatibility between all kinds of MS and

different BTS. It is an open interface

It realizes the physical connection between MS and CDMA

network.

Um interface


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Abis interface

The interface between BTS and BSC, used for remote

connection.

2.048 Mb/s PCM digital link


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A interface

It is the interface between BSC and MSC

It is based on 2.048Mb/S PCM digital links

A-Interface is mainly used to transmit the following

information:

BSS management information

Call processing

Mobility management


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B interface

The interface between MSC and VLR.

MSC transfer the location information of roaming

subscriber to VLR. Query subscriber data from VLR when setting up the

calls.

Usually VLR is built with MSC together, so the

interface turns to be an internal interface and has nostandard rules.


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The interface between MSC and HLR.

The interface is based on 2.048Mb/s PCM digital link.When an MS is called, MSC must query the called MSs

routing message from HLR through this interface to locate the

called MS, and according to the record, HLR will return the

routing message(MSC/VLR number) to MSC.

C interface


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D interface

The interface between VLR and HLR.

The interface is based on 2.048Mb/s PCM digital link.

The interface is used for exchange of subscriber location

information, authorization information and service data.


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E interface

The interface between one MSC and another MSC. It is used for

channel change over between 2 MSCs


When a mobile station roams from one MSC to another during

speech, the MSC will perform handover to keep the subscribers'

conversation uninterrupted. In this case, data exchanging must be

implemented between the MSCs.


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Q interface

Interface between SC/OMC and MSC. .



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Ai interface:

The interface between MSC and PSTN, used for setting up

voice connection between PSTN and PLMN.


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