Introduction To Gprs

INTRODUCTION TO GPRS

WHAT IS GPRS ? • GPRS is a new bearer service for GSM

• It is originally standardized by European Telecommunications Standards (ETSI) • Uses unused TDMA channels

Services offered "Always on" internet access Multimedia messaging service (MMS) Push to talk over cellular (PoC/PTT) Instant messaging and presence Internet applications for smart devices through wireless application protocol (WAP) • Higher data transfer rates (Data Rate 14.4 – 115 kbps) • • • • •

Protocols supported • Internet protocol • Point to point protocol • GTP (GPRS Tunneling Protocol) • WAP

GSM and GPRS GSM

GPRS

DATA RATES

9.6 Kbps

14.4 to 115.2 Kbps

Modulation Technique

GMSK

GMSK

Billing

Duration of connection

Amount of data transferred

Type of Connection

Circuit – Switched Packet Technology Switched Technology

GPRS support nodes • SGSN – Serving GPRS Support Node

• GGSN – Gateway GPRS Support Node

SGSN • De-tunnel GTP packets from the GGSN (downlink) • Tunnel IP packets toward the GGSN (uplink) • Carry out mobility management as Idle mode mobile moves

GGSN • Converts GPRS packets coming from the SGSN into the appropriate packet data protocol (PDP) format (e.g., IP or X.25) • PDP addresses of incoming data packets are converted to GSM address of the destination user • GGSN stores the current SGSN address and profile of the user in its location register. • Authentication and charging functions.

GPRS Core Network

Interfaces • Gb - Interface between the base station subsystem and the SGSN , the transmission protocol could be Frame Relay or IP • Gn - IP Based interface between SGSN and other SGSNs and (internal) GGSNs. • Gr - Interface between the SGSN and the HLR. Messages going through this interface uses the MAP3 protocol.

Interfaces • Gs - Interface between the SGSN and the MSC (VLR). Uses the BSSAP+ protocol. • Gi - IP based interface between the GGSN and a public data network (PDN) either directly to the Internet or through a WAP gateway.

GPRS Speeds • Speed drops logarithmically with distance from the base station. Coding Scheme

Speed (Kbps)

CS-1

9.05

CS-2

13.4

CS-3

15.6

CS-4

21.4

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GPRS 4+1

57.6 Kbit/s

14.4 Kbit/s

GPRS 3+2

43.2 Kbit/s

28.8 Kbit/s

CSD

9.6 Kbit/s

9.6 Kbit/s

HSCSD

28.8 Kbit/s

14.4 Kbit/s

HSCSD

43.2 Kbit/s

14.4 Kbit/s

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• NO ANIMALS WERE HARMED DURING MAKING OF THESE SLIDES