Switch System Components

7/28/2019 Switch System Components

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SWITCH SYSTEM COMPONENTS

Provides Interface (MSC)to radio network portion

of BSS & PSTN

Includes functional data

bases ::

- Visitor Location Register

- Home Location Register- Authentication Register

- Equipment Identity

Register


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VISITOR LOCATION REGISTER Temporarily stores information about MS attaches to RBS in area serviced

by MSC

Temporary subscriber information required by MSC to provide service tovisiting subscriber

When MS registers with new MSC service area - new VLR request subscriberinformation from MSs HLR

HLR sends subscriber information to VLR

If MS either sends or receives a call, VLR already has information for call setup

VLR integrated with MSC to form MSC/VLR


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MOBILE SWITCHING CENTER

Responsible for setting up, routing & supervision of voice calls to & from MS toPSTN

Includes VLR functionality addition to telephony switching functions yield anintegrated MSC/VLR system

Basic function performed by MSC/VLR are ::

- Setting up & control of Voice calls including subscribe

supplementary services

- Providing voice path continuity through use of handoff

- Call routing to roaming subscriber

- Subscriber registration, location & data updating

- MSs authentication, SMS delivery, signaling to other network elements

(HLR, BSC) and networks (PSTN & PLMNs)

-Charging & accounting


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MSC INTERFACE & SWITCHING FUNCTIONS

Trunk connections are used between Local Central Office(CO)exchange & long distance provider for high bit-rate digital signal

Synchronous Optical Networking (SONET) is fiber optic cable whichcarry optical signals in 100 mbps or higher

SONET is capable of transporting multiple T1/E1/J1 carriers

- T1/J1 support 24 digitized voice calls

- E1 has a capacity of 30 calls

MSC is another CO exchange has its own exchange routing number

N1/0N- NNX- XXXX

3 digit area code exchange number


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GROUP SWITCH Provides functionality in the MSC

Incoming voice call occupies TS#20 on a T1 carrier signal connected to a localexchange in PSTN

After demultiplexing signal is applied to group switch

Group switch processor implements a path that allows signal to be redirected toavailable TS#2 on line connected to BSC#4

Identical call path established in reverse direction to provide for duplex operation

Incoming voice calls on particular T1/E1/J1 carrier arrive assigned to a particulartime slot


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MSC SIGNALING FUNCTIONS

To coordinate the processing of calls both to & from MS,

MSC & BSC exchange messages using Message Transfer

Part (MTP)

MTP provides reliable transfer of signaling messages over

standard (T1/E1/J1) digital transmission links in parallel

with digital traffic links.


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MSC DATABASE FUNCTIONS

MSC/VLR continually send & receive data from HLR

AUC/EIR databases

Signaling & data transfer between the MSC/VLR & these

databases is carried out using MTP & SCCP (Signaling

Connection Control Port)


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HOME LOCATION REGISTER

Stores permanent data about the networks subscribers,information about subscribers contracted teleservices and

data about subscribers present location

Data includes MS identification numbers that identify both

mobile equipment & PSTN MS ID number consists of country code - national destination

code or number planning area code & subscriber number

HLR plays important role in process of handling calls &

terminating at the MS HLR analyzes the information about the incoming call and

controls routing of call


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HLR implementation & Operation

Integrated into an MSC/VLR to create an MSC/ VLR/

HLR

HLR consists of

storage , central processor, I/O system

traffic measurement data collection

SS7 signaling links are maintained between HLR &MSC/VLRs


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CONTINUE

HLR has two basic functions:

- It maintains databases of subscriber-

related information : consist of both permanent

data such as subscriber- associated MS numbers& dynamic data or location data

Support typical data base operations printing &modification of subscriber data & addition or deletion of

subscriber

Handling of authentication & encryption information

Performs call handling, routing of mobile terminating calls& handling of location updating


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HLR SUBSCRIPTION PROFILE

Store subscribers profile

Types of services available are TELESERVICES

(telephony, SMS, fax) & bearer services (data

services)

Supplementary services are

Call waiting, call holding, multiparty service, calling

line & connected line identification, call forwardingcall barring

Switch System Components

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