Content

1. Introduction
2. what is GPRS
3. The development of GPRS
4. The GPRS Network Aritecture
5. The services GPRS provides
Reference

The most common methods used for data transfer are circuit-switching and packet-switching.

The GPRS system use packet-switched connection services, overcomes the disadvantages of current circuit-switched system. It has short access time to the network and the call charging is based on amount of transmission data.

GPRS will be a tremendous step in GSM based mobile data, it will enable new types of services as a result of the "always connected" packet data connection.

GPRS is a new nonvoice value added service that allows information to be sent and received across a mobile telephone network[3]. It supplements today's circuit switched data and Short Message Service(SMS).It is a new service designed for digital cellular networks. It is an upgrade of the current GSM network that enables packet based data transfer between the GSM terminal and external packet network such as the internet.

GPRS as a basic service is very different from traditional teleservices. It uses a packet-mode technique to transfer data and signaling in a cost-efficient manner over GSM radio networks and also optimizes the use of radio and network resources, the resources allocated only when data is to be sent /received.

GPRS utilises a packet radio principle and can be used for carrying end user's packet data protocol (such as IP and X.25) information from/to a GPRS terminals to/from other GPRS terminals and/or external packet data networks.

Flexible channe allocation
* 1 to 8 time slots,
* Available resource shared by active users
* Up and down link channel reserved separately
* GPRS and circuit switched GSM services can use the same time slots altern atively

Connection with the network
*IP network
*x.25

Efficient delivery of SMSs over the GPRS interface

3 The development of GPRS

There are 2 phases to implement GPRS in order to manage the great amount of work required to produce the new standards. To support GPRS operations, new protocols and new network devices are required.

The ETSI standarddization work on the GPRS phase 1 is completed on 1998. It includes Point -to- Point (PTP) services and the whole basic GPRS infrastructure. It supports:

And the Air-interface, mobility management, QoS, GPRS support nodes and GPRS backbones are all parts of phase 1.

Phase 2 GPRS:

Phase 2 of GPRS completes the capabilities to meet GPRS requirements. It will add support for additional specific point-to-point and point-to-multipoint services, for applications such as traffic telematics and train control. Support for alternative user and network interfaces, e.g. ISDN and other packet networks, as well as support for additional supplementary services, will also be added.[2]

The TCP/IP and other network consider GPRS just as a normal subnetwork.

The current GSM system was originlly designed with an emphasis on voice session,the main objective of the GPRS is to offer a access to standard data network such as TCP/IP, X.25. To support GPRS operations, new protocols and new network devices are required.

The Serving GPRS Support Node (SGSN), which is at the same hierarchical level as the MSC, keeps track of the individual MSs' location and performs security functions and access control. The SGSN is connected to the base station system with Frame Relay[1].

The Gateway GSN (GGSN)provides interworking with external packet-switched networks, and is connected with SGSNs via an IP-based GPRS backbone network. The HLR is enhanced with GPRS subscriber information, and the SMS-MSCs are upgraded to support SMS transmission via the SGSN.Optionally, the MSC/VLR can be enhanced for more-efficient co-ordination of GPRS and non-GPRS services and functionality: e.g., paging for circuit-switched calls which can be performed more efficiently via the SGSN, and combined GPRS and non-GPRS location updates[1].

And also there are some other new elements such as: Point-to-Multipoint service center(PTM-SC),which is dedicated to the PTM services in the GPRS network. Border Gateway(BG), which is mainly for the secturity reasons and is situated on the connection to the Inter-PLMN backbone network. The Inter-PLMN and Intra-PLMN backbone network are also new elements, both IP-based network.

Class A MS can operate GPRS and other GSM services simultaneously,e.g.having a normal GSM voice call and receiving GPRS data packets at the same time.

Class-B MS can monitor control channels for GPRS and other GSM services simultaneously, but can only operate one set of services at one time.

Class-C GPRS MS can exclusively operate GPRS services.The selection is done manually and there is no simultaneously operation.[1]

The GPRS system give the service subscribers an opportunity to use the data services in an end-to-end packet transfer mode. There are 2 GPRS-specific application class :

5.1 Point-to-point(PTP) application

PTP service provides a medium for the packet transfer between 2 subscribers, one of which is sender and the other is the receiver. There are 2 types of PTP services: PTP Connectionless Network Service and PTP Connection Orientated Network Service.

PTP Connectionless service, which support the protocol like IP: When one user send packet to another, every packet is its own entity and it has no relation to the other, no matter the preceding packet or the the following packet. It is a datagram type of service.

PTP Connection orientated PTP service, which support the protocol likeX.25: Before send packet, a Switched Virtual Circuit is established between the subscriber and a logical relation between the packets is maintained. The delivery of the message is reliable.

5.2 Point-to-multipoint application

PTM services provide a medium for the packet transfer in one-to-many or many-to-many fashion.

Subscribers can use the PTM service to send a message to multiple receivers with only one service request through defining a geographical area where the message is sent and other attributes for the message. The GPRS has 3 PTM services: PTM-M, PTM-G and IP Multicast.

The voice mail sercvices are proving to be the key factor for mobile operators to keep up with new services the market demands as they represent the means to enhance significantly the quality of the service, increase the customer base and speed up the development of the network.

GPRS is a nonvoice mobile services , it provide a wide range of corporate and consumer applications, for example:

Advanced Business Applications[2]

1)tracking of taxis and credit card validation for customer payment
2)control over the position of trucks for transportation companies
3)localization of stolen cars
4)support of security and monitoring systems
5)distribution of specific short messages to selected groups of users in large
corporations

References:

[2]Mielck Lotte &Guillou Daniel&Mwakipesile Gibson, GPRS, last modified 27.11.998,[referred14.9.1999]
http://keskus.hut.fi/opetus/s38118/s98/htyo/54/tech.shtml

[3]MobileGPRS.com, What is GPRS? [referred 14.9.1999]
http://www.mobilegprs.com/whatis.htm