General Packet Radio Service: Kiran. R (1nh02ec058)

General Packet Radio Service KIRAN. R (1nh02ec058)

Outline • • • • • • •

History What is GPRS & It’s need Comparison GPRS architecture Application Limitations Conclusion

GPRS History • Established by ETSI(European Telecommunications Standards Institute) • GSM phase 1 --- 1992 • GSM phase 2 --- 1996 • GPRS begin in 1994 and published at the end of 1997

What is GPRS? • A new bearer service for GSM that greatly improves and simplifies wireless access to packet data networks,e.g to the internet.

Need for GPRS…. • Existing Cellular networks have problems: – – – – – –

Data Rates too slow – about 9.6 kbps Connections setup too long & complicated Proves expensive for bursty traffic utilization Inefficient resource utilization for bursty traffic No efficient method for packet transfers Not User friendly billing

GPRS Objectives • GPRS uses packet switched resource allocation • Dynamic channel allocation – 1 to 8 time slots – Available resources shared by active users – Up and down link channels reserved separately – GPRS and circuit switched (GSM) services can use same time slots alternatively

• GPRS also carries SMS in data channels rather than signaling channels as in GSM • Connections with data networks – IP network,X.25,GPRS own protocols

Packet-switched technique vs. circuit-switched • In circuit-switching, resources (e.g. a channel) are allocated to user for duration of connection – Inefficient use of resources – User pays for the whole connection

• In packet-switching, resources are allocated to user only for the time it takes to send each packet – – – –

A channel can serve many users User pays by the packet Ideal for bursty data connections High QoS: channel maintains real-time connection

Comparison  Packet-switched – High bit rates (up to 170kbit/s) – Shared bandwidth – Variable access times – Friendly bill (based on volume) – Robust application support • Frequent transmission of small volumes • Infrequent transmission of small or medium volumes

 Circuit-switched – Low bit rates (14.4kbit/s) – Reserved bandwidth – Fixed access time – Unfriendly bill (based on duration) – Limited application support • Large volumes

Comparison between GPRS & Circuit-switched

GPRS architecture

GPRS architecture • Requires addition of a new class of nodes called GSNs (GPRS Support Nodes) – SGSN: Serving GPRS Support Node, – GGSN: Gateway GPRS Support Node

GPRS Components • GPRS support node(GSN) – Packet routing and transfer within PLMN(Public Land Mobile Network)

• Gateway GPRS support node(GGSN) – Acts as a logical interface to external PDN(Packet Data Network)

• Serving GPRS support node(SGSN) – Delivery of packets to the MSs within its service area

GGSN : Gateway GPRS support node • Interfaces GPRS backbone network & external packet data networks • PDP (Packet data protocol)addresses change to GSM addresses • many-to- many relations among SGSNs & GGSNs

SGSN : Serving GPRS Support Node • Delivers data packets from and to mobile stations • Packet Routing and Transfer • Mobility Management • Logical Link Management

Service type of GPRS • GPRS provides two types of services: – PTP (Point-To-Point) • Connectionless: IP • Connection-oriented: X.25

– PTM (Point-To-Multipoint) • Multicast Service (PTM-M) • Group Call Service (PTM-G)

Three Modes of Operation • Class A – possibility to have simultaneously a circuit switched connection and a packet switched connection

• Class B – possibility to be attached for both Circuit and Packet Switching but can not use both services at the same time.

• Class C – allow to be attached to only one service at a time. (pure GSM or pure GPRS)

GSM v/s GPRS Auth. Email via GSM Server Email Server Modem Modem User GSM

Email via GPRS User GPRS

Internet

PSTN

Virtual GPRS Data Tunnel

INITIAL CALL PROCESS • • • •

GSM Call Train Modem Login and Authenticate Download mail Total

TIME (s) 4 30 11 180

3 min 45s

Repeat Above

Internet Authenticated path to Email server

INITIAL CALL PROCESS • • •

GPRS Call Login and Authenticate Download mail

Total

SUBSEQUENT CALL •

Auth. Server Email Server

TIME (s) 4 11 180

3 min 15s

SUBSEQUENT CALL 3 min 45s

• Not applicable – Permanent Virtual Circuit

0min

0s

Applications…. • Web browsing • E-mail • Banking Transactions • Stock Market Updates • News • Weather & Traffic reports

•Chat •Image •Audio •Video •GPS(Global Positioning System)

Limitations • New Terminals required • Actual Speeds may vary – may come down to about 38.4 kbps • Packet switching can lead to delays affecting the Quality of Service • Could have an impact on cell capacity • Its data rate is limited by the availability of time slots

Conclusions • GPRS is a part in the transition from 2G to 3G • GPRS is economical for the operators • Because of its salient features & implementations over different cellular bearers, over 100 million subscribers of 2G TDMA based technologies will benefit • With little cost & major benefits, GPRS provides easy solution to ISPs • Will pave the way for UMTS & EDGE