Basics of Cdma

Topics: Base station subsystem, GSM, Network switching subsystem Pages: 9 (1734 words) Published: August 13, 2011
Part1 Basic knowledge of CDMA

1. Architecture of CDMA system/ Coverage Area Structure 2. Interface between different entities 3. Numbering plan

Architecture of CDMA system
MS Um Abis A B OMC








•MS: •BSC: •BTS: •MSC: •VLR: •HLR: •AUC: •OMC:

Mobile Station Base Station Controller Base Transceiver Station Mobile Switching Center Visitor Location Register Home Location Register Authentication Center Operation and Maintenance Center

1.Main components of CDMA
•MSS (Mobile Switching Sub-system) •BSS (Base Station Sub-system) •MS (Mobile Station) •OMC (Operation and Maintenance Center)

1.1 Base Station Sub-system
•Function 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.

1.2 Mobile Switching Sub-system
•Function —CDMA switching function —Manage mobile subscriber data —Manage database for mobile service —Interface between CDMA network and other network (such as PSTN, other PLMN etc.). •It includes 4 function units: ---MSC ---HLR ---VLR ---AUC

1.2.1 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 • GMSC(gateway):When a non-CDMA end subscriber calls a CDMA subscriber, the call will first be routed to a GMSC. •It can process the No. 7 signaling between BSS and MSC, and realizes the auxiliary radio resource management and mobile management.

1.2.2 Visitor Location Register(VLR) •VLR is 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), user’s 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 data about this subscriber. • VLR

can be built together with the MSC or set separately.

1.2.3 Home Location Register(HLR • HLR:It is a static database. When a user applies for mobile service, all data of 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 up the call route to the MS. • HLR can be built together with the MSC or set separately.

1.2.4 Authentication Center

It is an entity to prevent illegal subscribers from accessing CDMA network. It can generate the parameters to confirm the subscriber’s identity. At the same time it can encrypt user’s data according to user’s request.

• Composition — Database save MIN,ESN, Authentication Key) — Generator of random number — Algorithm(CAVE algorithm) — AUC can be built separately or together with HLR


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 working efficiency 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. We also call OMC as background.

wireless Area partition

CDMA service area PLMNService area MSCService area Location area cell

Wireless coverage area structure

wireless Area partition
• Cell The smallest area that can not be divided. • Location area: The area where MS moves without updating location. It...
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