7/30/2019 2.5 G Systems

1/10

Data Rates too slow about 9.6 kbps

Connection setup time too long

Inefficient resource utilization

No efficient method for packet transfers

7/30/2019 2.5 G Systems

2/10

HSCSD : High Speed Circuit Switched Data GPRS : General Packet Radio Service EDGE : Enhanced Data Rate for GSM Evolution

7/30/2019 2.5 G Systems

3/10

It allows a single mobile subscriber to useconsecutive time slots in the GSM standard.Instead of limiting each user to only onespecific time slot in GSM TDMA standard.

This is done in order to obtain higher speeddata access on the GSM network.

7/30/2019 2.5 G Systems

4/10

By using up to four consecutive time slots,HSCSD is able to provide a raw transmissionrate of up to 57.6 kbps to individual users.

7/30/2019 2.5 G Systems

5/10

PARAMETER GSM GPRSData Rates 9.6 Kbps 14.4 to 115.2 Kbps

Modulation Technique GMSK GMSK

Billing Duration ofconnection

Amount of data

transferred

Type of Connection Circuit SwitchedTechnology

Packet - Switched

Technology

7/30/2019 2.5 G Systems

6/10

It is a packet-based data network. Well suited for applications like internet

usage ( including retrieval of email, faxes,asymmetric web browsing where the userdownloads much more data than it uploadson the internet).

Unlike HSCSD, which dedicates circuit

switched channels to specific users, GPRSsupports multi-user network sharing ofindividual radio channels and time slots.

7/30/2019 2.5 G Systems

7/10

As comparable to HSCSD , it can supportmore users

GPRS standard provides a packet network ondedicated GSM. It retains the original

modulation formats , but it completelyredefined air interface in order to handlepacket data access.

GPRS subscriber units are automatically

instructed to tune to dedicated GPRS radiochannels and particular time slots foralways-on access to the network.

7/30/2019 2.5 G Systems

8/10

When all eight time slots of a GSM radiochannel are dedicated to GPRS, an individualuser is able to achieve as much as 171.kbps.

Implementation of GPRS requires the GSMoperator to install new routers and Internetgateways at the base station, along with newsoftware that redefines the base station airinterface standard for GPRS channels andtime slots no new base station RF hardwareis required.

7/30/2019 2.5 G Systems

9/10

It is advanced upgrade to the GSM standardand requires the addition of new hardwareand software existing base stations.

It uses 8-PSK digital modulation format.

It allows for nine different air interfaceformats, known as multiple modulation andcoding schemes (MCS), with varying degreesof error control protection.

Each MCS state may use either GMSK or 8-PSK modulation for network access,depending on the instantaneous demands ofthe network and the operating conditions.

7/30/2019 2.5 G Systems

10/10

Because of higher data rates and relaxederror control covering in many of theselectable air interface formats, the coveragerange is smaller.

It supports data, multimedia services, andapplications at high-speed , close to threetimes the speed of GPRS.