General Packet Radio Service(Gprs)

7/29/2019 General Packet Radio Service(Gprs)

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GSM PHASE 2+

GENERAL PACKET RADIOSERVICE(GPRS)


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What Is GPRS?

General Packet Radio Service, more commonly known as GPRS,is a non-voice, value added, high-speed, packet-switching

technology, for GSM (Global System for MobileCommunications) NETWORKS.

GPRS offers faster data transmission via a GSM network within arange 9.6Kbits to 115Kbits (although conceptually up to 172Kbps

is possible). It reserves radio resources only when there is data tosend and uses packet-based transfer method instead of circuit-switching method used by GSM networks.


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Features Of GPRS

This new technology makes it possible for users to make telephonecalls and transmit data at the same time. (For example, if you have amobile phone using GPRS, you will be able to simultaneously makecalls and receive e-mail massages.)

Supports both TDMA (Time division Multiple Access) and GSMtechniques.

With GPRS, an IP data transmission protocol (used in INTERNET),

which is characteristic of computer networks, is being introduced toGSM.


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Features of GPRS

It makes it possible to send and receive small chunk of data such asin web-browsing as well as large amount of data on mobile phone

networks.

Its technology exists between that of todays widely in use GSMtechnology and tomorrows 3G(third gen.) technology.

GPRS resources are only needed while the message is beingtransferred. Hence , consumer pays less ,that is ,only for thedownloading the data and not for the whole time of connection.


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Features OF GPRS

GPRS allows us to send and receive data anytime as the needarises. NO dial-up modem is necessary.

GPRS makes internet facility available to mobile users .For

example, phones like NOKIA 6600give allow this facility of internet on phone,

whereas simple GSM phones allow you a

WAP browser(Wireless Application Protocol)

which allow you to load WAP pages while on

move. (Next Page)
http://www.filesaveas.com/6600.html


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GPRS To Access Internet


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Features Of GPRS

GPRS involves overlaying a packed based air interface on existingGSMnetworks. that is , information is split into related packetsbefore being transmitted and then reassembled again at receivingstation.

Due to packet switching technique, the spectrum efficiencyincreases since radio resources are used only when user is

sending and receiving data.

Allows multiple users to use the same bandwidth.


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Comparison

56 K

Dial-up

GSM GPRS

(ideal)

GPRS

(actual)

56Kbps 9.6Kbps 43-56Kbps 171.2Kbps


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History Behind GPRS1999-2000 Incorporation of GPRS into GSM

networks.2000 summer First trail versions available at

28Kbps.

2001 Network operators launch GPRScommercially.

2001/2002 Speed increased to 56Kbps.Otherfeatures include higher bit

rate,higher network resolution etc.

2002 GPRS is routinely incorporated intomobiles.

2002/2003 3GSM arrive in the market.


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GSM Architecture (in brief)


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GSM Architecture

GSM mobile station is denoted as MS.

A cell is formed by the radio area coverage of Base Transcieverstation (BTS).

Several BTS combined together form one Base Service Controller(BSC).

Several BTS and one BSC together form Base Station Subsystem(BSS).

The combined traffic of mobile stations is routed through Mobile

Switching Center (MSC).Connections originating from fixed stations is handled by dedicatedGateway Mobile Switching Center (GMSC).


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GSM Architecture

Permanent data such as user profile and temporary data such asusers current location is stored in HLR (Home Location Register).In case of call to a user ,his HLR is contacted to find his currentlocation.

VLR (Visited Location Register) us responsible for list of userscurrently in its area of command.

AUC (Authentication Control) contains information such as keys

used for authentication and encryption.

EIR (Equipment Identity Register) contains information regardingequipment data instead of user data.


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GSM Working

The International Mobile Station Equipment Identity(IMEI)uniquely identifies a mobile station internationally. It is a kind ofserial number. The IMEI is allocated by the equipment manufacturerand registered by the network operator who stores it in the EIR.

Each registered user is uniquely identified by its InternationalMobile Subscriber Identity (IMSI). It is stored in the SubscriberIdentity Module (SIM).

A mobile station can only be operated if a SIM with a valid IMSI isinserted into equipment with a valid IMEI.


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GPRS Architecture


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GPRS Working

In order to integrate GPRS into the existing GSM architecture, a newclass of network nodes, called GPRS support nodes (GSN), hasbeen introduced. GSNs are responsible for the delivery and routing

of data packets between the mobile stations and the externalPacket Data Networks (PDN).

A ServingGPRS Support Node (SGSN) is responsible for thedelivery of data packets from and to the mobile stations within its

service area. Its tasks include packet routing, mobility managementand authentication and charging functions.


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GPRS Working

A Gateway GPRS Support Node (GGSN) acts as an interfacebetween the GPRS backbone network and the external packet datanetworks. It converts the GPRS packets coming from the SGSN intothe appropriate Packet Data Protocol (PDP) format (e.g., IP orX.25) and sends them out on the corresponding Packet Data

Network (PDN) In the other direction, PDP addresses of incomingdata packets are converted to the GSM address of the destinationuser. The readdressed packets are sent to the responsible SGSN.For this purpose, the GGSN stores the current SGSN address of theuser and his or her profile in its location register. The GGSN alsoperforms authentication and charging functions.

In general, there is a many-to-many relationship between theSGSNs and the GGSNs: A GGSN is the interface to external packetdata networks for several SGSNs; an SGSN may route its packetsover different GGSNs to reach different Packet Data Networks(PDN) .


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GPRS Services

The bearer service of GPRS offers end-to-end packet switcheddata transfer. These are of two kinds:

1. The point-to-point (PTP) service offers transfer of data betweentwo users. Its offered both in connection mode and connectionlessnode.

2. The point-to-multipoint (PTM) offers transfer of data from one

user to multiple users. Its offered in multicast service (PTM-M)where one message is distributed over whole geographic areagroup and other is group call service (PTM-G) where messageis distributed to a particular group of users.


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GPRS Services

The supplementary services includes various extra facilities givento users .For example:

1. It is also possible to send SMS messages over GPRS.

2. It is planned to implement closed user group (CUG) service verysoon.

3. As a location manager. That is , it will be easy to locate onesposition using GPRS phones.


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Classes Of Mobile Stations

In a GSM/GPRS network, conventional circuit switched services(speech, data, and SMS) and GPRS services can be used inparallel. Three classes of mobile stations are defined :

1. A class A mobile station supports simultaneous operation of GPRSand conventional GSM services.

2. A class B mobile station is able to register with the network forboth GPRS and conventional GSM services simultaneously. Incontrast to an MS of class A, it can only use one of the two servicesat a given time.

3. A class C mobile station can attach for either GPRS orconventional GSM services. Simultaneous registration (and usage)is not possible. An exception are SMS messages, which can bereceived and sent at any time


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Routing In GPRS


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Routing In GPRS

A GPRS mobile station located in Public Land Mobile NetworkPLMN1 sends IP packets to a host connected to the IP network, TheSGSN that the mobile station is registered with encapsulates the IP

packets coming from the mobile station, examines the PDP context,and routes them through the intra-PLMN GPRS backbone to theappropriate GGSN. The GGSN decapsulates the packets and sendsthem out on the IP network, where IP routing mechanisms are usedto transfer the packets to the access router of the destination

network. The latter delivers the IP packets to the host.


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Location Management In GPRS


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Three States In GPRS

In IDLE state the MS is not reachable.

Performing a GPRS attach, the MS gets into READY state.

With a GPRS detach it may disconnect from the network and fallback to IDLE state.

The STANDBY state will be reached when an MS does not send

any packets for a longer period of time, and therefore the READYtimer (which was started at GPRS attach) expires.


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Location Management In GPRS

In IDLE state, no location updating is performed.

An MS in READY state informs its SGSN of every movement to a

new cell.

For the location management of an MS in STANDBY state, a GSMlocation area (LA) is divided into several routing areas (RA).TheSGSN will only be informed when an MS moves to a new RA.


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Security

GPRS security functionality is equivalent to the existing GSMsecurity. The SGSN performs authentication and cipher setting

procedures based on the same algorithms, keys, and criteria as inexisting GSM. GPRS uses a ciphering algorithm optimised forpacket data transmission.


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Applications Of GPRS

Textual And Graphical Messages: A wide range of content can bedelivered to mobile phone users. This information need notnecessarily be textual- it may be maps or graphs or other types ofvisual information.

Chat: GPRS would allow mobile users to participate fully in existingInternet chat groups rather than needing to set up their own groupsthat are dedicated to mobile users.

Moving Images: The nature and form of mobile communication isgetting less textual and more visual. Videoconferencing is anotherapplication for moving images.


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Job Dispatch: Non-voice mobile services can be used to assignand communicate new jobs to mobile field staff. GPRS non-voiceservices can be used not only to send the job out, but also as ameans for the service engineer or sales person can keep the officeinformed of progress towards meeting the customers requirement .

Internet connections And E-mails: GPRS can be used to connectinternet through your mobile phones. its possible to send andreceive mails through mobile.
http://www.filesaveas.com/6600.html


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LAN Access: A user will soon be able to connect to his office orhome LAN through his mobile itself as if he is sitting at the disk .

File Transfer: File transfer applications encompass any form ofdownloading sizeable data across the mobile network. The file couldbe anything such as .pdf files or some word documents or some httpfiles. This type of application is bandwidth intensive.


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Limitations Of GPRS

Limited Radio Resources: Even todaythe resources of thecompany are not sufficient to handle the flow of traffic. Henceservice is not sufficient.

Speed Much Lower In Reality: Attaining maximum speed of171.2Kbps would mean giving all the 8-timeslots to a single userwhich is a constraint for the companies. Only 1-3 timeslots perTDMA are given hence the speed is so low (around 56Kbps).

Suboptimal Modulation:GPRS is based on modulation techniquecalled Guassian Minimum Shift Keying (GMSK) whereas EDGE isbased on 8-Phase Shift Keying(8-psk) which supports higher bitrate.


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Limitations Of GPRS

Transit Losses Possible: Since GPRS works on principle of packetswitching, hence, there is every possibility of some being lost orsome getting delayed in traffic.

No Store And Forward Technique Available: There is no storagemechanism incorporated in GPRS techniques whereas SMStechniques use store and forward technique.


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Summary

The General Packet Radio Service GPRS is an important step inthe evolution toward third-generation mobile networks.

Its packet switched transmission technology is optimized forbursty traffic such as Internet/intranet services.

One of the main benefits for users is that they can always be onlineand may be charged for service based on the amount of transmitteddata.

The GPRS system architecture has two new network nodes,namely, the SGSN and GGSN apart from the basic structure ofGSM networks.


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References

During the preparation of seminar , following sites helped me alot:

1. www.gsmworld.com

2. www.comsoc.org

3. www.topology.com

4. www.filesaveas.com

5. www.webopidia.com
http://www.gsmworld.com/http://www.comsoc.org/http://www.topology.com/http://www.filesaveas.com/http://www.webopidia.com/http://www.webopidia.com/http://www.filesaveas.com/http://www.topology.com/http://www.comsoc.org/http://www.gsmworld.com/

General Packet Radio Service(Gprs)

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