Mobile communication
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Mobile Communication. MMS / GPRS. What is GPRS ?. General Packet Radio Service (GPRS) is a new bearer service for GSM that greatly improves and simplifies wireless access to packet data networks

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Mobile Communication

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Mobile communication

Mobile Communication

MMS / GPRS


What is gprs

What is GPRS ?

  • General Packet Radio Service (GPRS) is a new bearer service for GSM that greatly improves and simplifies wireless access to packet data networks

  • GPRS applies packet radio principal to transfer user data packets in an efficient way b/w MS & external packet data network


Benefits of gprs

Benefits of GPRS

  • New Data Services

  • High Speed (Data Rate 14.4 – 115 kbps)

  • Efficient use of radio bandwidth (Statistical Multiplexing)

  • Circuit switching & Packet Switching can be used in parallel

  • Constant connectivity


Comparison of gsm gprs

Comparison of GSM & GPRS


High data rate

High Data Rate

  • GPRS uses radio channel i.e. 200 kHz wide

  • Radio channel carries digital data stream of 271 kbps

  • This rate is divided into 8 time slots each carrying 34 kbps per time slot

  • Data rate 14 kbps per time slot achieved after corrections

  • GPRS can combine upto 8 time slots giving data rate of 114 kbps


Gprs terminals

GPRS Terminals

  • Class A

    • MS supports simultaneous operation of GPRS and GSM services

  • Class B

    • MS able to register with the n/w for both GPRS & GSM services simultaneously. It can only use one of the two services at a given time.

  • Class C

    • MS can attach for either GPRS or GSM services


Gprs network elements

GPRS Network Elements

GPRS Architecture is same as GSM except few hardware modifications :

  • GPRS includes GSNs

    • SGSN : Serving GPRS Support Node

    • GGSN : Gateway GPRS Support Node

  • GPRS Register


  • Gsm system architecture

    GSM SYSTEM ARCHITECTURE

    PSTN

    ISDN

    PDN

    BSC

    MS

    BTS

    MSC/VLR

    GMSC

    BTS

    BSC

    MS

    EIR

    BTS

    AUC

    MS

    HLR


    Gprs system architecture

    GPRS SYSTEM ARCHITECTURE

    Other GPRS

    PLMN

    Gd

    SMS-GMSC

    SMS-INMSC

    SGSN

    Gp

    GGSN

    Gb

    Gn

    GGSN

    Gf

    BTS

    BSC

    Gr

    Gs

    PDN

    Gi

    Gc

    BTS

    EIR

    HLR+GPRS Register

    MS

    D

    MSC/VLR


    Sgsn serving gprs support node

    SGSN – Serving GPRS Support Node

    • Delivers data packets to mobile stations & vice-versa

    • Detect and Register new GPRS MS in its serving area

    • Packet Routing, Transfer & Mobility Management

    • Authentication, Maintaining user profiles

    • Its location register stores location info. & user profiles


    Ggsn gateway gprs support node

    GGSN – Gateway GPRS Support Node

    • Interfaces GPRS backbone network & external packet data networks

    • Converts the GPRS packets from SGSN to the PDP format

    • Converts PDP addresses <Packet Data Protocol> change to GSM addresses of the destination user

    • Stores the current SGSN address and profile of the user in its location register

    • Performs authentication

    • Many-to- many relations among SGSNs & GGSNs


    Session management in gprs

    SESSION MANAGEMENT IN GPRS


    Attachment detachment procedure

    Attachment & Detachment Procedure

    • GPRS attach

      • User is registered in SGSN, after authentication check from HLR

      • SGSN assigns P-TMSI to MS

    • GPRS detach

      • Disconnection of MS from GPRS network is called GPRS detach

      • It can be initiated by MS or by network(SGSN or HLR)


    Session management

    Session Management

    • Mobile Station applies for PDP address <link-local address>

    • For each session PDP context is created & it contains

      • PDP type

      • PDP addressed assigned to MS

      • Address of GGSN that servers access point to PDN

  • With active PDP context MS able to send or receive data packets

  • Allocation of PDP address can be static or dynamic


  • Pdp context activation

    PDP Context Activation


    Channels in gprs

    Channels in GPRS

    • Logical Channel

      • Traffic Channels

      • Signaling Channels (Control Channels)

    • Physical Channels


    Logical channels

    Logical Channels


    Packet data channel pdch

    Packet Data Channel(PDCH)

    • Physical Channel for GPRS Traffic

    • PDCH are taken from all channels available in the cell

    • Depending on current traffic load and priority of service, the physical channel are allocated to either GPRS or GSM services.

    • Physical channels not currently used by GSM can be allocated as PDCH to increase the QOS for GPRS


    Multiframe structure of pdch

    Multiframe Structure of PDCH

    Four consecutive TDMA frame forms one block - B0 – B11

    Two TDMA frames for transmission of PTCCH - T

    Two Idle frames - X


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