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Packet Core Network and

Billing System for GSM

Service

Basic Information by AmitPokharel

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GSM Vs GPRS

GSM based on circuit switch architecture(dedicated line)

while GPRS is packet based.

Rate of data transmission is 9.6 kbps for GSM while 384kbps for GPRS

GSM specially for voice calling while GPRS is for

internet using

In generation term GSM -2 G while GPRS 2.5 G

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Packet Vs Circuit

file f ilfe = file

e

i lPacket switching

fileestablish

filetransfer

release

Circuit Switching

AB

A B

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GPRS architecture

Gr GcMAP MAP

Iu-PS

Gn Gi

RANAP GTP TCP

Gp

GTP

RNC SGSN GGSN Inter

net

HLR

GGSN of

other n/w

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GPRS Block Description

SGSN- used for packet switching , routing and transfer

and charging fns means cdr generation

GGSN- used as a gateway that connects SGSN withexternal n/w like internet or other plmn.

HLR- permanent database that stores all the detailed

information of mobile subscribers

RNC handover, cell configuration, control of radio

frequency etc.

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Interfaces and Protocols

RANAP- used for paging, radio access mgmt etc.

MAP used to access HLR,VLR, EIR,AUC, SMSC,

SGSN etc.

- fn is to location update and mgmt, subscriber tracing,GPRS function etc.

GTP- used within GPRS core n/w for signaling between

SGSN and GGSN.

TCP- connection oriented, reliable, ordered type ofmessage transferring protocol

-provides acknowledgement in each transfer

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GSM Architecture

BICC Nc

MAP

H.248Mc MAP Mc H.248

A

BSSAP Nb RTP

MSCS

/VLR

GMSC

/VLR

MGW GMG

W

PSTNBSC

HLR

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GSM Block Description

MSCS voice channel switching, call controlling,

charging, mobility mgmt

GMSCS

passes voice signalling between fixed n/w andmobile n/w

MGW media like audio, video controlling

GMGW gateway to other plmn like pstn, pabx

BSC- frequency administration, control of BTS, handover

operation

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Interface and Protocol

Mc interface used in betwn MSCS & MGW , protocol

H.248

Nc

interface used betwn MSC Servers, protocol BICC

Nb interface used betwn media gateways, protocol

RTP

A interface used in betwn Radio n/w(BSC) and Core

n/w, protocol BSSAP

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Billing

Billing is to collect consumption data, calculate charging.

GTP FTPSGSN ChargeGateway

Billing

Center

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Protocol

GTP used between SGSN and CG to transfer billing

data

FTP

used to transfer files from one host to anotherhost over TCP based n/w such as through internet

UDP connection less, unreliable

Thank You