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Research Paper # 1

ON THE WAY TO 3G NETWORKS:

“THE GPRS/EDGE CONCEPT”

Vasil P. Pribylov , Member ,IEEE, Ivan I.Rezvan

Siberia State University of Telecommunications & Informatics

Email: v.pribylov@ieee.org

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Abstract

Describe Principles and use of GPRS.

Main problems of transition towards the UMTS

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IntroductionGrowing interest in mobile data applications lead a cause of GSM to

GPRS

GPRS a 2.5 G system allows the transmission of packet data at moderate bit rates using random access channels within the 2G infrastructure.

Mobile applications contain several characteristics that enhance the value to the customers Like

mobility(constant voice & data services while on the move)immediacy (obtaining connectivity when needed,

regardless of location and without a lengthy login session).

localization (allows subscribers to obtain information on their current location)

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Introduction cont….GPRS Protocol Stack is important as a

migration step toward third-generation (3G) networks.

When GSM operators start to offer GPRS services, they can use their existing networks and gradually assign part of their resources from circuit-switched voice services to packet-switched data services.

This allows a smooth transition from voice-only to multimedia service networks.

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GPRS BACKGROUNDEnable new & existing applications onto GSM

Enhancement of GSM’s functional & QoS parameter.

GPRS shall support both connectionless & connection oriented services.

Offer flexible service at low cost to the user.

Use scarce network resources as efficiently as possible

GPRS BACKGROUND cont……

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Required to efficiently use network resources for packet mode applications.

New mechanisms are required in order to provide highly standardized, feature rich services.

Three types of service request were distinguished:

1-Broadcast:A point to multipoint message sent to “all service subscribers” within an area defined by the service requester.

2-Multicast:A point to multipoint message sent to “”an identical subset of all service subscribers” within the area defined by the service requester.

3-Singlecast:A point to point message sent to “a unique subscriber”.

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GPRS BACKGROUND cont……The GPRS operator shall be responsible for

transferring data between the service access points at the fixed side and at the mobile side. The flow of data shall be possible in three scenarios.

1. Packets sent from a mobile access point to a fixed network access point.

2. Packets sent from a fixed network access point to a mobile access point.

3. Packets sent from a mobile access point to a mobile access point via the GSM operator infrastructure

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Principles of GPRSUsers specifically need a mobile phone or terminal supporting GPRS ,

subscription to a network.

GPRS network resources accessed only when data actually need to be transmitted between the GPRS user and the network.

Data are divided into packets and then transmitted via the radio & core GPRS network.

Packet switched traffic is separated from circuit switched traffic at BSC & diverted to GPRS core network.

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GPRS use GMSK modulation scheme.

Information is coded in the increase(+ve shift) or (-ve shift) of the carrier phase.

In GMSK ,initially signal passed through pre-modulation Gaussian filter for pulse-shaping.

Principles of GPRS (Cont.)

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GPRS NODES

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Frequency reuse factorError coding scheme(CS)Data packet delay

Strong channel coding: convolutional code recovers most of the transmission errors. However , the effective throughput of data packets is small due to the low code rate.

Weak channel coding: Each RLC block carries a high payload & the whole RLC block has to be retransmitted.

Link Layer Performance of GPRS Network

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GPRS Limitations & Security AspectsTheoretical maximum GPRS data transmission speed only when a

user utilize eight timeslots without any protection.

Bandwidth available to a GPRS user is severely limited.

Misuse of their resources by unauthorized persons using manipulated mobile stations.

Eaves-dropping the information being exchanged on the radio path.

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MS authentication: Protection of GPRS subscribers by denying intruders the ability to impersonate authorized users

Access Control: Network can support restrictions on access by or to different subscriber e.g. location, screening lists etc.

User Identity Confidentiality: User identity is not disclosed to unauthorized individuals, entities or processes.

User Information Confidentiality: the property that the user information is not made available or disclosed to unauthorised individuals, entities or processes. The purpose is to provide for confidentiality of user data.

GPRS Limitations & Security

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EXPERIMENTexperimented with the Eriksson R580m

mobile phone(using “4+1” time slots four slots in

“downlink” for receiving and one slot in “uplink” for requesting the information

GPRS connection with one of Novosibirsk GPRS operators – Siberia Cellular Systems network of Russia.

web-site www.nsk.mts.ru

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Result

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INTRODUCING EDGEEDGE is an enhanced version of GPRSusing a different modulation technique, eight-

level Phase Shift Keying (8PSK), that has a spectral efficiency of 3bits/s/Hz in comparison of GMSK’s 1bit/s/Hz.

For this reason EDGE requires a hardware upgrade of the RF part in the base stations.

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Conclusion and Future WorkGPRS allows network operators to implement an IP-

based core architecture for data applications, which continues to be used and expanded upon in 3G services for integrated voice and data applications

Speed is still not fulfilling the demand of customers.Advancement in GPRS system will be the use of improved coding

techniques.

GPRS proves to be a testing & development area for new services & application which will be used for 3G services.

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Conclusion and Future Work,GPRS/EDGE acts as transition technique towards 3G

& a great need of UMTS/GSM dual-mode.But UMTS operators can not start planning from zerosince the best solution is that the existing

GSM base station sites are to be the primary sites for UMTS base stations.

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REFERENCES[1] GPRS Overview,

http://www.vocal.com/data_sheets/gprs1.html.[2] GSM World: GPRS Platform,

http://www.gsmworld.com/technology/gprs/index.shtml.

[3] ETSI TR 101.186 V6.0.0 (1998-04): “General Packet Radio Service (GPRS)”, 19 p.

[4] Cellular System Solutions for GSM/GPRS Wireless Terminals, 21 March 2003, http://www.3g.co.uk/PR/March2003/5070.htm.

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Thank you