General Packet Radio Service

An Overview

Ashish Bansal

General Concepts

• Packet mode technique for xmitting high speed and low speed data and signaling

• New GPRS radio channels with flexible allocation

• Four different QoS levels are defined• MS can operate in 3 different modes of

operation• Two new nodes - SGSN and GGSN

GSM and GPRS Architecture

GPRS Layers

GPRS Layers contd...• GPRS Tunneling Protocol (GTP): for tunneling data and signaling between

GSNs in the network.• GPRS Mobility Management and Session Management (GMM/SM): for GPRS

attach, GPRS detach, security, routeing area update, location update, PDP context activation and deactivation

• Subnetwork Dependent Convergence Protocol (SNDCP): Maps different packet data protocols (like IP, X.25) to a common level.

• Logical Link Control (LLC): provides highly reliable ciphered logical link.• Relay: Exists on BSS and SGSN. Responsible for mapping LLC PDUs

between Um and Gb interfaces. In SGSN maps between Gb and Gn interfaces.• Base Station System GPRS Protocol (BSSGP): For conveying routing and QoS

related information between BSS and SGSN.• Network Service (NS): For transporting BSSGP PDUs. Based on frame relay.• Radio Link Control/Medium Access Control (RLC/MAC): RLC provides radio-

solution dependant reliable link. MAC controls request and grant procedures for the radio channel and mapping of LLC frames onto GSM channels..

GPRS Operation

• GPRS Attach

• PDP Context Activation

• Data transfer

• PDP Context Deactivation/GPRS Detach

GPRS Attach

GPRS Attach contd...

PDP Context Activation

GPRS Data Transfer

GPRS Detach

References

• C Bettstetter, H Vogel, J Eberspacher, “GSM Phase 2+ General Packet Radio Service GPRS: Architecture, Protocols, and Air Interface”, IEEE Communications Survey, vol. 2 no. 3, pp 2-14, IIIrd quarter 1999.

• GSM 03.60 - GPRS Service Description

• GSM 08.18 - BSS GPRS Protocol

• GSM 04.07 - Mobile radio interface Layer 3: General Aspects

• See http://www.etsi.org