gprs full report

7/28/2019 GPRS Full Report

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Seminar Report

On

General Packet Radio Service (GPRS)

Course Title: Seminar

Course No.: ECE 4204

Date of Submission: 28-05-2013

Khulna University

Electronics and Communication Engineering Discipline

Khulna-9208

Submitted By

Group No-09

A. K. M. Tohidur Rahman

Student ID: 090918

S. M. M. Hossain Mahmud

Student ID: 090924

Tapan Kumar Biswas

Student ID: 090933

4th Year, 2nd Term

ECE Discipline

Khulna University

Khulna-9208

Submitted To

Sehrish Khan

Associate Professor

ECE Discipline

Khulna University

Khulna-9208

&

Dr. Md. Sohel Mahmud Sher

Associate Professor

ECE Discipline

Khulna University

Khulna-9208


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ACKNOWLEDGEMENT

I thank God Almighty for the successful completion of my seminar. I express my sincere

gratitude to Sehrish Khan, Associate Professor and Dr. Md. Sohel Mahmud Sher, Associate

Professor, ECE Discipline, Khulna University, Khulna-9208.

Finally, I wish to thank all my dear friends, for their whole-hearted cooperation, support and

encouragement.


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ABSTRACT

Today's mobile professionals need to stay in regular contact with important sources of

information such as the internet, email, corporate networks and remote databases. As demand

for Wide Area Networking (WAN) connectivity continues to grow, users and organizations

are seeking ways to make it more efficient and productive. One of the most promising new

technologies for this purpose is General Packet Radio Service (GPRS). GPRS is a packet-

switching data network that is overlaid on the existing cellular voice network, using the same

radio frequencies and cellular towers. When combined with the existing Global System for

Mobile communication (GSM), GPRS offers a complete voice and data solution with

significant advantages over other solutions. GPRS offers the flexibility and throughput of

packet switching. GPRS uses packet switching to transfer data from the mobile device to the

network and back. On a packet switched network a device can be always connected and ready

to send information without monopolizing the channel. Channels are shared in packet-

switched network, but in circuit-switched each channel is dedicated to one user. There are no

call up or suspend delays. By overlaying the GSM network, GPRS is able to take advantage

of the world's leading digital phone system. This is about three times as fast as the data

transmission speeds possible over today's fixed telecommunications networks and ten times

as fast as current Circuit Switched Data services on GSM networks.


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TABLE OF CONTENTS

Chapters Topics Pages

Chapter 1 Introduction 6

1.1 Need For a Wireless WAN Solution 6

1.2 A bit of history 7

1.2.1 First Generation Wireless Technology 7

1.2.2Second Generation Wireless Technology

7

1.2.3Second Generation Plus (2G+) Wireless Networks

7

Chapter 2 GPRS Overview 9

2.1 Who owns GPRS? 9

2.2 Goals of GPRS 9

2.3 Advantages of GPRS 10

2.4 Key NetworkFeatures of GPRS 11

2.4.1 Packet switching 11

2.4.2 Spectrum efficiency 12

2.4.3 Internet aware 12

Chapter 3 GPRS Architecture 14

3.1 GPRS Network Overview 14

3.2 Subscriber Terminal Devices 14

3.3 Radio Base Station Network 15

3.4 Network Switching and Services Infrastructure 15


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3.5 Additional Network Functionality 16

3.5.1 Serving GPRS Support Node (SGSN) 16

3.5.2 Gateway GPRS Support Node (GGSN) 16

3.6 Internal Backbone 17

3.7 GPRS Interfaces and Reference Points 17

Chapter 4 GPRS Protocol Architecture 20

4.1 Physical Layer 20

4.2 RLC/MAC Layer 22

4.3 LLC Layer 22

4.4 SNDCP Layer 22

4.5 BSSGP Layer 23

4.6 GTP Layer 24

Chapter 5 GPRS in Action 25

5.1 Attachment and Detachment Procedure 25

5.2 Session Management 25

5.3 Data Packet Routing 27

5.4 Location Management 28

5.5 Routing Update in GPRS 30

Chapter 6 GPRS Packet Data Channels 31

6.1 Time Slot Aggregation 31

6.2 Logical Channels in GPRS 32

6.3 Channel Coding 33


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Chapter 7 GPRS Security 34

7.1 Subscriber Identity Confidentiality 34

7.2 Identifying method 34

7.3 GPRS Authentication 35

7.4 GSM confidentiality 35

Chapter 8 GPRS Charging and Billing Techniques 37

Chapter 9 Limitations/ Problems RegardingGPRS Technology 38

Chapter 10 GPRS Applications 39

Chapter 11 Conclusion 42

Glossary 43

Reference 46


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CHAPTER 1

INTRODUCTION

Wireless wide area cellular network solutions have been around for many years.

Widespread adoption has been slow due to issues with coverage, cost, performance, and

secure remote access to business networks. The deployment of the Global System for Mobile

Communications (GSM) based General Packet Radio Service (GPRS) has the potential to

change this situation and to provide connectivity anytime and anywhere. GPRS is a packet

based radio service that enables always on connections, eliminating repetitive and time

consuming dial up connections. It will also provide real throughput in excess of 40 Kbps,

about the same speed as an excellent land line analog modem connection.

1.1 Need for a Wireless WAN Solution

Mobile workers who need to access information while they travel can do so using one

of two Wide Area Networking methods - wired or wireless. In the past, they relied mainly on

wired methods such as analog modems to connect over the public switched telephone

network (PSTN). However, users realized that using a dial up method to get a connection

were relatively tedious and time consuming, and connections were sometimes difficult to

maintain. In addition, as networking has progressed, the circuit- switched phone network has

proved to have limitations for data transmission compared to packet-switched networks such

as the Internet and corporate LANs. And finally, wired methods do not provide the same

degree of mobility as wireless solutions. The advent of wireless data communication through

the use of mobile phones and alphanumeric pagers has provided a higher degree of flexibility

over wired mobile connections. Today, users are able to connect their notebook and handheld

computers to data sources using mobile phone connection kits, and the data is sent over the

mobile phone network. However, mobile phones are still relatively slow in terms of data

throughput, and pagers can only display small amounts of information. Manufacturers are

rapidly developing a wide variety of new client devices, and advanced transmission

capabilities are also required. Mobile data users, businesses and other organizations have

asked for the freedom of wireless, but with the performance of wired connections. One of the

most promising technologies for meeting these needs is General Packet Radio Service


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(GPRS). This wireless data transmission technology can be used to send data over large

geographic areas to create the next evolution of wireless WANs (WWANs).

1.2 A BIT OF HISTORY

1.2.1 First Generation Wireless Technology

The first generation of wireless mobile communications was based on analog signaling.

Analog systems, implemented in North America, were known as Analog Mobile Phone Systems

(AMPS), while systems implemented in Europe and the rest of the worlds were typically identified as

a variation of Total Access Communication Systems (TACS). Analog systems were primarily based

on circuit-switched technology and designed for voice, not data.

1.2.2 Second Generation Wireless Technology

The second generation (2G) of the wireless mobile network was based on low band

digital data signaling. The most popular 2G wireless technology is known as Global Systems

for Mobile Communications (GSM). GSM technology is a combination of Frequency

Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA). The first

GSM systems used a 25MHz frequency spectrum in the 900MHz band. FDMA is used to

divide the available 25MHz of bandwidth into 124 carrier frequencies of 200 kHz each. Each

frequency is then divided using a TDMA scheme into eight time slots. The use of separate

time slots for transmission and reception simplifies the electronics in the mobile units. Today,

GSM systems operate in the 900MHz and 1.8 GHz bands throughout the world with the

exception of the Americas where they operate in the 1.9 GHz band. While GSM technology

was developed in Europe, Code Division Multiple Access (CDMA) technology was

developed in North America. CDMA uses spread spectrum technology to break up speech

into small, digitized segments and encodes them to identify each call. The Second Generation

(2G) wireless networks mentioned above are also mostly based on circuit-switched

technology. 2G wireless networks are digital and expand the range of applications to more

advanced voice services, such as Called Line Identification. 2G wireless technology can

handle some data capabilities such as fax and short message service at the data rate of up to

9.6 kbps, but it is not suitable for web browsing and multimedia applications.


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1.2.3 Second Generation Plus (2G+) Wireless Networks

The effective data rate of 2G circuit-switched wireless systems is relatively slow for

today's Internet. As a result, GSM and other TDMA-based mobile system providers and

carriers have developed 2G+ technology that is packet- based and increases the data

communication speeds to as high as 384kbps. These 2G+ systems are based on the following

technologies High Speed Circuit-Switched Data (HSCSD), General Packet Radio Service

(GPRS) andEnhanced Data Rates for Global Evolution (EDGE)technologies. HSCSD is one

step towards 3G wide band mobile data networks. This circuit-switched technology improves

the data rates up to 57.6kbps by introducing 14.4 kbps data coding and by aggregating 4 radio

channels time slots of 14.4 kbps. GPRS is an intermediate step that is designed to allow the

GSM world to implement a full range of Internet services without waiting for the deployment

of full scale 3G wireless systems. GPRS uses a multiple of the 1 to 8 radio channel time slots

in the 200 kHz-frequency band allocated for a carrier frequency to enable data speeds of up to

115kbps. EDGE technology is a standard that has been specified to enhance the throughput

per time slot for both HSCSD and GPRS.


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Chapter 2

GPRS OVERVIEW

GPRS is a Mobile Data Service available to users of GSM and IS-136 mobile phones. GPRS is packet-switched and multiple users share the same transmission channel for

transmitting the data.

2.1 Who owns GPRS?

The GPRS specifications are written by the European Telecommunications Standard

Institute (ETSI), the European counterpart of the American National Standard Institute

(ANSI).GPRS stands for General Packet Radio System. GPRS provides packet radio access

for mobile Global System for Mobile Communications (GSM) and time-division multiple

access (TDMA) users.

GPRS is important as a migration step toward third-generation (3G) networks and

allows network operators to implement IP-based core architecture for data applications,

which will continue to be used and expanded for 3G services for integrated voice and data

applications.GPRS is a new bearer service for GSM that greatly improves and simplifies

wireless access to packet data networks, e.g., to the Internet. It applies a packet radio

principle to transfer user data packets in an efficient way between GSM mobile stations and

external packet data networks. Packets can be directly routed from the GPRS mobile stations

to packet switched networks. Networks based on the Internet Protocol (IP) (e.g., the global

Internet or private/ corporate intranets) and X.25 networks are also supported in the current

versions of GPRS.

2.2 Goals of GPRS

GPRS is the first step toward an end-to-end wireless infrastructure and has the following

goals:

Open architecture Consistent IP services Same infrastructure for different air interfaces Integrated telephony and Internet infrastructure


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Leverage industry investment in IP Service innovation independent of infrastructure

2.3 Advantages of GPRS

GPRS provides faster data transfer rates, always on connection, robust connectivity,

broad application support and strong security mechanisms.

Fast Data Transfer Rates

GPRS currently supports an average data rate of 115 Kbps, but this speed is only

achieved by dedicating all eight time slots to GPRS. Instead, carriers and terminal devices

will typically be configured to handle a specific number of time slots for upstream and

downstream data. For example, a GPRS device might be set to handle a maximum of four

slots downstream and two slots upstream. Under good radio conditions, this yields speeds of

approximately 50 Kbps downstream and 20 Kbps upstream. This is more than three times

faster than current 14.4-Kbps GSM networks and roughly equivalent to a good land line

analog modem connection. The aggregate cell site bandwidth is shared by voice and data

traffic. GPRS operators will vary in how they allocate the bandwidth. Typically, they will

configure the networks to give precedence to voice traffic; some may dedicate time slots to

data traffic to ensure a minimum level of service during busy voice traffic periods. Unused

voice capacity may be dynamically reallocated to data traffic. With its faster data transfer

rates, GPRS enables higher bandwidth applications not currently feasible on a GSM network.

Always-On Connection

An always on connection eliminates the lengthy delays required to reconnect to the

network to send and receive data. Information can also be pushed to the end user in real time.

GPRS allows providers to bill by the packet, rather than by the minute, thus enabling cost

effective always on subscriber services.

Robust Connectivity

GPRS improves data transmission integrity with a number of mechanisms. First, user

data is encoded with redundancies that improve its resistance to adverse radio conditions. The

amount of coding redundancy can be varied, depending on radio conditions. GPRS has


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defined four coding schemes CS1 through CS4. Initially, only CS1 and CS2 will be

supported, which allows approximately 9 and 13 Kbps in each time slot. If an error is

detected in a frame received in the base station, the frame may be repeatedly retransmitted

until properly received before passing it on to the GPRS core network.

Broad Application SupportLike the Internet, GPRS is based on packet-switched data. This means that all native

IP applications, such as email, Web access, instant messaging, and file transfers can run over

GPRS. In addition, its faster data transfer rates enable GPRS to accommodate higher-

bandwidth applications (such as multimedia Web content) not suited to slower GSM dial-up

connections. GPRS is particularly well suited for applications based on the WirelessApplication Protocol (WAP). WAP has gained widespread acceptance in a new breed of

micro browser enabled phones.

Security Support

GPRS builds on the proved authentication and security model used by GSM. At

session initiation, a user is authenticated using secret information contained on a smart card

called a Subscriber Identity Module (SIM). Authentication data is exchanged and validated

with records stored in the HLR network node. GPRS enables additional authentication using

protocols such as RADIUS before the subscriber is allowed access to the Internet or corporate

data networks. GPRS supports the ciphering of user data across the wireless interface from

the mobile terminal to the SGSN. In addition, higher level, end to end VPN encryption may

take place when a user connects to a private corporate network.

2.4 KEY NETWORK FEATURES OF GPRS

2.4.1 Packet switching

GPRS involves overlaying a packet based air interface on the existing circuit switched

GSM network. This gives the user an option to use a packet-based data service. With GPRS,

the information is split into separate but related "packets" before being transmitted and

reassembled at the receiving end. Packet switching is similar to a jigsawGPRS, the

information is split into separate but related "packets" before being transmitted andreassembled at the receiving end. Packet switching is similar to a jigsaw puzzle- the image


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that the puzzle represents is divided into pieces at the manufacturing factory and put into a

plastic bag. During transportation of the now boxed jigsaw from the factory to the end user,

the pieces get jumbled up. When the recipient empties the bag with all the pieces, they are

reassembled to form the original image. All the pieces are all related and fit together, but the

way they are transported and assembled varies.

Characteristic Circuit Switching Packet Switching

Need to establish a Connection

Dedicated Path

Bandwidth allocation

Potentially wasted bandwidth

Same path for all data

Congestion can occur at

Yes

Yes

Fixed

Yes

Yes

Setup time

No

No

Dynamic

No

No

Any time

2.4.2 Spectrum efficiency

Packet switching means that GPRS radio resources are used only when users are

actually sending or receiving data. Rather than dedicating a radio channel to a mobile data

user for a fixed period of time, the available radio resource can be concurrently shared

between several users. This efficient use of scarce radio resources means that large numbers

of GPRS users can potentially share the same bandwidth and be served from a single cell.

The actual number of users supported depends on the application being used and how much

data is being transferred. Because of the spectrum efficiency of GPRS, there is less need to

build in idle capacity that is only used in peak hours. GPRS therefore lets network operators

maximize the use of their network resources in a dynamic and flexible way, along with user

access to resources and revenues.

Table 1: Circuit switching vs. Packet


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2.4.3 Internet aware

For the first time, GPRS fully enables Mobile Internet functionality by allowing

interworking between the existing Internet and the new GPRS network. Any service that is

used over the fixed Internet today- File Transfer Protocol (FTP), web browsing, chat, email,

telnet- will be as available over the mobile network because of GPRS. In fact, many network

operators are considering the opportunity to use GPRS to help become wireless Internet

Service Providers in their own right.. There is a trend away from storing information locally

in specific software packages on PCs to remotely on the Internet .Each GPRS terminal can

potentially have its own IP address and will be addressable as such.


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Chapter 3

GPRS ARCHITECTURE

3.1 GPRS Network Overview

GPRS is a data network that overlays a second-generation GSM network. This data

overlay network provides packet data transport at rates from 9.6 to 171 kbps. Additionally,

multiple users can share the same air-interface resources simultaneously. GPRS attempts to

reuse the existing GSM network elements as much as possible, but to effectively build a

packet-based mobile cellular network, some new network elements, interfaces, and protocols

for handling packet traffic are required. To supply this capability, a GPRS network consists

of three basic components:

3.2 Subscriber Terminal Devices

Today, these devices are typically cell phones, but there are other devices such as

personal digital assistants (PDAs) with various input/output capabilities. All have integrated

radio transceivers.

Types of devices: GPRS devices are also classified by their ability to handle voice and

data calls. There are three such classifications:

Class A mode of operation: The MS is attached to both GPRS and other GSM services. The

mobile user can make and/or receive calls on the two services simultaneously, subject to the

quality of service (QoS) requirements, e.g. having a normal GSM voice call and receiving

GPRS data packets at the same time.

Class B mode of operation: The MS is attached to both GPRS and other GSM services, but

the MS can only operate one set of services at a time. The MS in idle mode (and packet idle

mode) is required to monitor paging channels (PCHs) for both circuit-switched and packet-

switched services. However, the practical behavior of the MS depends on the mode of

network operation. For example, one mode of network operation is defined so that when an

MS is engaged in packet data transfer, it will receive paging messages via the packet data

channel (PDCH) without degradation of the packet data transfer.

Class C mode of operation: The MS can only be attached to either the GSM network or theGPRS network. The selection is done manually and there are no simultaneous operations.


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3.3 Radio Base Station Network

Cellular networks are composed of small, low powered, terrestrial radio cells that

typically range in coverage area from tens of kilometers in sparsely populated rural areas to

less than 500 meters in densely populated urban areas. The frequencies used by the network

are reused again and again in different cells throughout the network to increase network

capacity.

3.4 Network Switching and Services Infrastructure

The traffic to and from the radio network is concentrated at a set of switching nodes

that interface to other fixed public or private networks. These nodes handle the call setup,

channel resource allocation, and the administration of subscriber services. These components

allow the GSM network to provide coverage as a user moves from an area covered by one

cell to an area covered by another cell. The network terminates the old cell connection and

immediately establishes a new cell connection. This process is designed to be transparent to

the user. In addition, users can roam or travel outside of a home coverage area to a new city,

region, or country. The arrival of the visitor is detected by the new system through an

automatic registration process. The new system informs the users home system of the new

location so that calls can be delivered.

Many registers are also maintained which contain information necessary for the

smooth functioning of the network. The HLR (Home Location Register) stores information

Figure 01: Functional View of GPRS Architecture [6]

Localareanetwork

Server

Router

Localareanetwork

Server

Router

Corporate 2

Corporate 1

Intra-PLMNbackbonenetwork

(IP based)

Serving GPRSSupport Node(SGSN)

Point-To-MultipointServiceCenter(PTM SC)

Gateway GPRSSupport Node(GGSN)

GPRSINFRASTRUCTURE

HLR/AuC

MSC

BSCBTS PacketnetworkPSTN

PacketnetworkSS7Network

Packetnetwork

Datanetwork(Internet)

Packetnetwork

Datanetwork(X.25)

Packetnetwork

Inter-PLMNBackbone

network

BorderGateway (BG)

Gb

Gr Gd

Gi.IP

Gi.X.25

Firewall

Firewall

Firewall

UmR/S

SMS-GMSC

Gr Gd

Gs

Gs

Gp

Gn

Gn

EIR

MAP-F


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about the current location of all subscribers of the network. This information is necessary for

routing all calls/messages to their intended destinations. A VLR (Visitor Location Register)

covers one or more cells and stores information about the subscribers currently under its area

of influence.

3.5 Additional Network Functionality

Although GPRS reuses existing GSM network elements, some new protocols,

interfaces and other network elements is required (see Figure 1). These include two major

core network elements, the Serving GPRS Support Node (SGSN) and the Gateway GPRS

Support Node (SGSN)

3.5.1 Serving GPRS Support Node (SGSN)

The SGSN is a main component of the GPRS network, which handles, e.g. the

mobility management and authentication and has register function. The SGSN is connected to

the BSC and is the service access point to the GPRS network for the GPRS MS. The SGSN

handles the protocol conversion from the IP used in the backbone network to the sub-

network-dependent convergence protocol (SNDCP) and logical link control (LLC) protocols

used between the SGSN and the MS. These protocols handle compression and ciphering. The

SGSN also handles the authentication of GPRS mobiles, and when the authentication is

successful; the SGSN handles the registration of an MS to the GPRS network and takes care

of its mobility management. When the MS wants to send (or receive) data to (from) external

networks, the SGSN relays the data between the SGSN and relevant GGSN (and vice versa).

3.5.2 Gateway GPRS Support Node (GGSN)

The GGSN is connected to the external networks like the Internet and the X.25. From

the external networks point of view, the GGSN is a router to a sub -network, because the

GGSN hides the GPRS infrastructure from the external networks. When the GGSN receives

data addressed to a specific user, it checks if the address is active. If it is, the GGSN forwards

the data to the SGSN serving the MS, but if the address is inactive, the data are discarded.

The mobile-originated packets are routed to the right network by the GGSN. The GGSN

tracks the MS with a precision of SGSN.


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3.6 Internal Backbone

The internal backbone is an IP based network used to carry packets between different

GSNs. Tunneling is used between SGSNs and GGSNs, so the internal backbone does not

need any information about domains outside the GPRS network. Signaling from a GSN to a

MSC, HLR or EIR is done using SS7.

Routing Area

GPRS introduces the concept of a routing area. This is much the same as a Location

Area in GSM, except that it will generally contain fewer cells. Because routing areas are

smaller than Location Areas, less radio resources are used when a paging message is

broadcast.

3.7 GPRS Interfaces and Reference Points

The GPRS system introduces new so-called G-interfaces to the GSM network

architecture. It is important to understand the function of every interface and reference point

because this gives an insight to the GPRS system and consequent evolution. Figure 02 gives a

logical architecture description with the interfaces and reference points of the GSM networkwith GPRS.

Figure 02: Logical architecture description with the interfaces and reference points oftheGSM network with GPRS [6]


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Connections of the GPRS system to the network and switching sub-system (NSS) part of

the GSM network are implemented through signaling system number 7 (SS7) network (Gc,

Gd, Gf, Gr, Gs), while the other interfaces and reference points are implemented through the

intra-PLMN backbone network (Gn), the inter-PLMN backbone network (Gp) or the external

networks (Gi). The different interfaces that the GPRS system uses are as follows:

Gb between an SGSN and a BSS. The Gb interface is the carrier of the GPRS trafficand signaling between the GSM radio network (BSS) and the GPRS part. Frame

relaybased network services (NSs) provide flow control for this interface.

Gc between the GGSN and the HLR. The GGSN may request location information fornetwork requested context activation only via this optional interface. The standard

also defines the use of a proxy GSN, which is used as a GPRS tunnelling protocol

(GTP) to mobile application part (MAP) protocol converter, thus avoiding

implementing MAP in GGSN.

Gd between the SMS-GMSC and an SGSN, and between SMS-IWMSC and anSGSN. The Gd interface allows more efficient use of the SMS services.

Gf between an SGSN and the Equipment Identity Register (EIR). The Gf gives theSGSN access to equipment information. In the EIR, the MSs are divided into three

lists: black list for stolen mobiles, grey list for mobiles under observation and white

list for other mobiles.

Gn between two GSNs within the same PLMN. The Gn provides a data and signalinginterface in the intra-PLMN backbone. The GTP is used in the Gn (and in the Gp)

interface over the IP-based backbone network.

Gp between two GSNs in various PLMNs. The Gp interface provides the samefunctionality as the Gn interface, but it also provides, with the BG and the Firewall,

all the functions needed in the inter-PLMN networking, i.e. security, routing, etc.

Gr between an SGSN and the HLR. The Gr gives the SGSN access to subscriberinformation in the HLR, which can be located in a different PLMN than the SGSN.

Gs between an SGSN and an MSC. The SGSN can send location data to the MSC orreceive paging requests from the MSC via this optional interface. The Gs interface

will greatly improve effective use of the radio and network resources in the combined

GSM/GPRS network. This interface uses BSSAP+ protocol.

Um between a MS and the GPRS fixed network part. The Um is the access interfacefor the MS to the GPRS network. The MS has a radio interface to the BTS, which is

the same interface used by the existing GSM network with some GPRS-specific


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changes. There are two different reference points in the GPRS network. The Gi is

GPRS-specific, but the R is common with the circuit-switched GSM network. The

two reference points in the GPRS are as follows:

Gi between a GGSN and an external network. The GPRS network is connected toexternal data networks via this interface. The GPRS system will support a variety of

data networks and that is why the Gi is not a standard interface, but merely a

reference point.

R between terminal equipment and mobile termination. This reference point connectsterminal equipment to mobile termination, thus allowing, e.g. a laptop-PC to transmit

data over the GSM phone. The physical R interface follows, e.g. the ITU-T V.24/V.28

or the PCMCIA PC-Card standards.

Therefore, GPRS requires modifications to numerous GSM network elements as

summarized below:

GSM Network

Element

Modification or Upgrade Required for GPRS

Subscriber Terminal A totally new subscriber terminal is required to access GPRS

services. These new terminals will be backward compatible with

GSM for voice calls.

BTS A software upgrade is required in the existing base transceiver site

(BTS).

BSC The base station controller (BSC) will also require a software

upgrade, as well as the installation of a new piece of hardware

called a packet control unit (PCU). The PCU directs the data

traffic to the GPRS network and can be a separate hardware

element associated with the BSC.

Core Network The deployment of GPRS requires the installation of new core

network elements called the Serving GPRS Support Node (SGSN)

and Gateway GPRS Support Node (GGSN).

Databases (VLR,

HLR and so on)

All the databases involved in the network will require software

upgrades to handle the new call models and functions introduced

by GPRS.

Table 2: Modifications on GSM Network


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Chapter 4

GPRS Protocol Architecture

The GPRS system introduces a whole new set of protocols for the GSM Phase 2+

network. The inter-working between the new network elements is done with new GPRS-

specific protocols. However, there are a number of existing protocols used at the lower layers

of the protocol stacks, namely, TCP/user datagram protocol (UDP) IP. Figure 03 shows the

transmission plane used in the GPRS system

4.1 Physical Layer

The physical layer has been separated into two distinct sub-layers, the physical RF

layer and the physical link layer.

The physical RF layer performs the modulation of the physical waveforms based on

the sequence of bits received from the physical link layer. The physical RF layer also

demodulates received waveforms into a sequence of bits that are transferred to the physical

link layer for interpretation. The GSM physical RF layer is defined in GSM 05 series

specifications, which define the following among other things:

The carrier frequency characteristics and GSM radio channel structures.

Figure 03: GPRS Protocol Architecture [15]


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The modulation of the transmitted waveforms and the raw data rates of GSMchannels.

Note that in the GPRS Rel97 radio interface, only the original GSM modulation method,

GMSK modulation, with the carrier bit rate of 270.833 kbps is defined. For one single

timeslot; this corresponds to the gross data rate of 22.8 kbps.

The transmitter and receiver characteristics and performance requirements.

Thephysical link layerprovides services for information transfer over a physical channel

between the MS and the network. These functions include data unit framing, data coding and

the detection and correction of physical medium transmission errors. The physical link layer

operates above the physical RF layer to provide a physical channel between the MS and the

network. The purpose of the physical link layer is to convey information across the GSM

radio interface, including RLC/MAC information. The physical link layer supports multiple

MSs sharing a single physical channel and provides communication between MSs and the

network. In addition, it provides the services necessary to maintain communications

capability over the physical radio channel between the network and MSs. Radio sub-system

link control procedures are specified in.

The physical link layer is responsible for the following:

Forward error correction (FEC) coding, allowing the detection and correction oftransmitted code words and the indication of uncorrectable code words. The coding

schemes are described in the section entitled Physical link layer.

Rectangular interleaving of one radio block over four bursts in consecutive TDMAframes, as specified in.

Procedures for detecting physical link congestion. The physical link layer controlfunctions include

Synchronization procedures, including means for determining and adjusting the MStiming advance to correct for variances in propagation delay,

Monitoring and evaluation procedures for radio link signal quality. Cell selection and re-selection procedures. Transmitter power control procedures. Battery power saving procedures, e.g. discontinuous reception (DRX) procedures.


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4.2 RLC/MAC Layer

The RLC/MAC layer provides services for information transfer over the physical

layer of the GPRS radio interface. These functions include backward error correction

procedures enabled by the selective re-transmission of erroneous blocks. The RLC function

offers a reliable radio link to the upper layers. The MAC function handles the channel

allocation and the multiplexing, i.e. the use of physical layer functions. The RLC/MAC layer

together form the open system interconnection (OSI) Layer 2 protocol for the Um interface

and uses the services of the physical link layer (see the section entitled Medium Access

Control and Radio Link Control Layer).

4.3 LLC Layer

The logical link control layer offers a secure and reliable logical link between the MS

and the SGSN to upper layers, and is independent of the lower layers. The LLC layer has two

transfer modesthe acknowledged and unacknowledged. The LLC conveys signaling, SMS

and SNDCP packets.

4.4 SNDCP Layer

The sub-network-dependent convergence protocol (SNDCP) is a mapping and

compression function between the network layer and lower layers. It also performs

segmentation, reassembling and multiplexing. The SNDCP protocol is specified in [11].

Signaling has various sets of protocols, which are used with the existing GSM network

elements. Internal signaling in the GPRS system is handled by protocols, which carry both

data and signaling (LLC, GTP and BSSGP). The GPRS control plane is shown in Figure 04.

Figure 05 describes how network protocols are multiplexed. NSAPI is the network

layer service access point identifier, which is used to identify the packet data protocol (PDP)

context at SNDCP level. Service access point identifier (SAPI) is used to identify the points

where LLC provides service to higher layers. SAPIs have different priorities. TLLI is the

temporary logical link identity, which unambiguously identifies the logical link between the

MS and the SGSN. The IP or the X.25 is the packet protocol offered to the subscriber by the

GPRS system.


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4.5 BSSGP Layer

The primary functions of the base station sub-system GPRS protocol (BSSGP)

include, in the downlink, the provision by an SGSN to a BSS of radio-related information

used by the RLC/MAC function; in the uplink, the provision by a BSS to an SGSN of radio-

related information derived from the RLC/MAC function; and the provision of functionality

to enable two physically distinct nodes, an SGSN and a BSS, to operate node management

control functions. The underlying network service is responsible for the transport of BSSGP

packet data units (PDUs) between a BSS and an SGSN.

Figure 04: GPRS control plane [15]


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4.6 GTP Layer

The GPRS tunneling protocol (GTP) is used to tunnel data and signaling between the

GSNs. The GTP can have proprietary extensions to allow proprietary features. The relay

function relays PDP (packet data protocol) PDUs between the Gb and the Gn interfaces.

Figure 05:Network rotocols multi lex 15


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Chapter 5

GPRS IN ACTION

When a user turns on a GPRS device, typically it will automatically scan for a local

GPRS channel. If an appropriate channel is detected, the device will attempt to attach to the

network. The SGSN receives the attach request, fetches subscriber profile information from

the subscribers HLR node, and authenticates the user. Ciphering may be established at this

point.

The SGSN uses the profile information (including the access point name, which identifies the

network and operator) to determine which GGSN to route to. The selected gateway may

perform a Remote Authentication Dial In User Service (RADIUS) authentication and allocate

a dynamic Internet Protocol (IP) address to the user before setting up connections to outside

networks. This process is called the packet data profile context activation and the setup may

vary from one carrier to the next. It may include additional functions like QoS management.

When the mobile device is powered off or moved out of a GPRS coverage area, its context is

deactivated and the device is detached from the network.

How does a GPRS work?

5.1 Attachment and Detachment Procedure

Before a mobile station can use GPRS services, it must register with an SGSN of the

GPRS network. The network checks if the user is authorized, copies the user profile from the

HLR to the SGSN, and assigns a packet temporary mobile subscriber identity (PTMSI) to the

user. This procedure is called GPRS attach. For mobile stations using both circuit switched

and packet switched services it is possible to perform combined GPRS/IMSI attach

procedures. The disconnection from the GPRS network is called GPRS detach. It can be

initiated by the mobile station or by the network (SGSN or HLR).

5.2 Session Management

To exchange data packets with external PDNs after a successful GPRS attach, a

mobile station must apply for one or more addresses used in the PDN and e.g. for an IP

address in case the PDN is an IP network. This address is called PDP address (Packet Data


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Protocol address). For each session, a so called PDP context is created, which describes the

characteristics of the session. It contains the PDP type (e.g., IPv4), the PDPaddress assigned

to the mobile station (e.g., 129.187.222.10), the requested QoS, and the address of a GGSN

that serves as the access point to the PDN. This context is stored in the MS, the SGSN, and

the GGSN.

With an active PDP context, the mobile station is visible for the external PDN and is

able to send and receive data packets. The mapping between the two addresses, PDP and

IMSI, enables the GGSN to transfer data packets between PDN and MS. A user may have

several simultaneous PDP contexts active at a given time. The allocation of the PDP address

can be static or dynamic. In the first case, the network operator of the users home PLMN

permanently assigns a PDP address to the user. In the second case, a PDP address is assigned

to the user upon activation of a PDP context. The PDP address can be assigned by the

operator ofthe users home-PLMN (dynamic home- PLMN PDP address) or by the operator

of the visited network (dynamic visited-PLMN PDP address). The GGSN is responsible for

the allocation and the activation/ deactivation of the PDP addresses.

Figure 06 shows the PDP context activation procedure. Using the message activate PDP

context request, the MS informs the SGSN about the requested PDP context. If dynamic

PDP address assignment is requested, the parameter PDP address will be left empty.

Figure 06: PDP context activation procedure [7]


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Afterward, usual security functions (e.g., authentication of the user) are performed. If access

is granted, the SGSN will send a create PDP context request message to the affected

GGSN. The latter creates a new entry in its PDP context table, which enables the GGSN to

route data packets between the SGSN and the external PDN. Afterward, the GGSN returns a

confirmation message create PDP context response to the SGSN, which contains the PDP

address in case dynamic PDP address allocation was requested. The SGSN updates its PDP

context table and confirms the activation of the new PDP context to the MS (activate PDP

context accepts).

GPRS also supports anonymous PDP context activation. In this case, security functions

as shown in Figure are skipped, and thus, the user (i.e., the IMSI) using the PDP context

remains unknown to the network. Anonymous context activation may be employed for pre-

paid services, where the user does not want to be identified. Only dynamic address allocation

is possible in this case.

5.3 Data Packet Routing

The main functions of the GGSN involve interaction with the external data network.

The GGSN updates the location directory using routing information supplied by the SGSNs

about the location of a MS and routes the external data network protocol packet encapsulated

over the GPRS backbone to the SGSN currently serving the MS. It also decapsulates and

forwards external data network packets to the appropriate data network and collect charging

data that is forwarded to a charging gateway.

In Figure 3, three different routing schemes are illustrated: mobile-originated message (path

1), network-initiated message when the MS is in its home network (path 2), and network-

initiated message when the MS has roamed to another GPRS operators network (path 3). In

these examples, the operators GPRS network consists of multiple GSNs (with a gateway and

serving functionality) and an intra-operator backbone network.

GPRS operators will allow roaming through an inter-operator backbone network. The

GPRS operators connect to the inter-operator network via a boarder gateway (BG), which can

provide the necessary interworking and routing protocols (for example, Border Gateway

Protocol [BGP]). It is also foreseeable that GPRS operators will implement QoS mechanisms


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over the inter-operator network to ensure service-level agreements (SLAs). The main benefits

of the architecture are its flexibility, scalability, interoperability, and roaming.

5.4Location Management

The main task of location management is to keep track of the users current location,

so that incoming packets can be routed to his or her MS. For this purpose, the MS frequently

sends location update messages to its current SGSN. If the MS sends updates rather seldom,

its location (e.g., its current cell) is not known exactly and paging is necessary for each down

link packet, resulting in a significant delivery delay. On the other hand, if location updates

happen very often, the MSs location is well known to the network, and the data packets can

be delivered without any additional paging delay. However, quite a lot of uplink radio

capacity and battery power is consumed for mobility management in this case. Thus, a good

location management strategy must be a compromise between these two extreme methods. A

state model shown in Figure 4 has been defined for location management in GPRS. A MS

can be in one of three states depending on its current traffic amount.

Figure 07: Data Routing Procedure [1]


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Fig 08: States of GPRS in a Mobile Station [10]

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 fall back to idle

state. All PDP contexts will be deleted.

The standby state will be reached when an MS does not send any packets for a

longer period of time, and therefore the ready timer (which was started at GPRS attach)

expires. In idle state, no location updating is performed, i.e., the current location of the MS is

unknown to the network.

An MS in ready state (active state) informs its SGSN of every movement to a

new cell. For the location management of an MS in standby state, a GSM location area (LA)

is divided into several routing areas (RA). In general, an RA consists of several cells. The

SGSN will only be informed when an MS moves to a new RA; cell changes will not be

disclosed. To find out the current cell of an MS in standby state, paging of the MS within a

certain RA must be performed .For MSs in ready state, no paging is necessary.


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5.5 Routing Update in GPRS

When an MS that is in an active or a standby state moves from one routing area to

another within the service area of one SGSN, it must perform a routing update. The routing

area information in the SGSN is updated, and the success of the procedure is indicated in the

response message.

A cell-based routing update procedure is invoked when an active MS enters a new

cell. The MS sends a short message containing the identity of the MS and its new location

through GPRS channels to its current SGSN. This procedure is used only when the MS is in

the active state.

The inter-SGSN routing update is the most complicated routing update. The MSchanges from one SGSN area to another and it must establish a new connection to a new

SGSN. This means creating a new logical link context between the MS and the new

SGSNand informing the GGSN about the new location of the MS.

Figure 9: Routing Area Update [11]


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Chapter 6

GPRS Packet Data Channels

The channel allocation in GPRS is different from the original GSM. GPRS allows a

single mobile station to transmit on multiple time slots of the same TDMA frame

(multislotoperation). GPRS can combine multiple slots in a single transmission, the effective

bandwidth is increased the theoretical limit for GPRS is eight time slots. GPRS assigns a .5-

millisecond time slot to each data packet. The system is notified at the time of transmission as

to how many time slots or kbps is needed on both the sending and receiving devices. The

ability to combine only the required number of time slots for each transmission gives GPRS

the flexibility to support both low-speed and high-speed data applications in a single network.

6.1 Time Slot Aggregation

In conventional GSM, a channel is permanently allocated for a particular user during

the entire call period (whether data is transmitted or not). In contrast to this, in GPRS the

channels are only allocated when data packets are sent or received, and they are released after

the transmission. For bursty traffic this results in a much more efficient usage of the scarce

radio resources. With this principle, multiple users can share one physical channel. A cell

supporting GPRS may allocate physical channels for GPRS traffic. Such a physical channel is

denoted as packet data channel (PDCH). The PDCHs are taken from the common pool of all

channels available in the cell. Thus, the radio resources of a cell are shared by all GPRS and

non-GPRS mobile stations located in this cell. The mapping of physical channels to either

packet switched (GPRS) or circuit switched (conventional GSM) services can be performed

dynamically (capacity on demand principle, depending on the current traffic load, the priority

of the service, and the multislot class. A load supervision procedure monitors the load of the

PDCHs in the cell. According to the current demand, the number of channels allocated for

GPRS (i.e., the number of PDCHs) can be changed. Physical channels not currently in use by

conventional GSM can be allocated as PDCHs to increase the quality of service for GPRS.

When there is a resource demand for services with higher priority, PDCHs can be de-

allocated.


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6.2 Logical Channels in GPRS

On top of the physical channels, a series of logical channels are defined to perform a

multiplicity of functions, e.g., signaling, broadcast of general system information,

synchronization, channel assignment, paging, or payload transport. They can be divided into

two categories

Traffic channels Signaling (control) channels.

The packet data traffic channel (PDTCH) is employed for the transfer of user data. It is

assigned to one mobile station (or in the case of PTM to multiple mobile stations). One

mobile station can use several PDTCHs simultaneously.

The packet broadcast control channel (PBCCH) is a unidirectional point-to-multipoint

signaling channel from the base station subsystem (BSS) to the mobile stations. It is used by

the BSS to broadcast specific information about the organization of the GPRS radio network

to all GPRS mobile stations of a cell. Besides system information about GPRS, the PBCCH

should also broadcast important system information about circuit switched services, so that a

GSM/GPRS mobile station does not need to listen to the broadcast control channel (BCCH).

The packet common control channel (PCCCH) is a bidirectional point-to-multipoint

signaling channel that transports signaling information for network access management, e.g.,

for allocation of radio resources and paging. It consists of four sub-channels:

1. The packet random access channel (PRACH) is used by the mobile to request one ormore PDTCH.

2. The packet access grant channel (PAGCH) is used to allocate one or more PDTCH toa mobile station.

3. The packet paging channel (PPCH) is used by the BSS to find out the location of amobile station (paging) prior to downlink packet transmission.

4. The packet notification channel (PNCH) is used to inform a mobile station ofincoming PTM messages (multicast or group call).


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6.3 Channel Coding

Channel coding is used to protect the transmitted data packets against errors. The

channel coding technique in GPRS is quite similar to the one employed in conventional

GSM. The selection of coding schemes is transparent to the user and determines the level of

error correction the network users to send the data. The better the link is between the user and

the network, the less error correction is needed. Less error correction means higher

throughput. (Coding scheme 1 has the highest level of error correction.)

Scheme Data Rates(Kbps)

CS-1 9.05

CS-2 13.4

CS-3 16.6

CS-4 21.4

Table 3: Channel coding


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Chapter 7

GPRS SECURITY

GPRS is secure. It is an overlay on the existing GSM network. Hence it uses all

security features of the GSM network, along with its on options.

7.1 Subscriber Identity Confidentiality

The purpose of this function is to avoid an intruder to identity a subscriber on the

radio path (e.g. Traffic Channel or signaling resources) by listening to the signaling

exchanges. This function can be achieved by protecting the subscribers IMSI (International

Mobile Subscriber Index) and any signaling information elements. Therefore, a protected

identifying method should be used to identify a mobile subscriber instead of the IMSI on the

radio path. The signaling information elements that convey information about the mobile

subscriber identity must be transmitted in ciphered form. And also a ciphering method is

used.

7.2 Identifying method

The TMSI (Temporary Mobile Subscriber Index) is used in the method. Its a local

number and only valid in a given location area. The TMSI must be used together with the

LAI to avoid ambiguities. The network manages the databases (e.g. VLR) to keep the relation

between TMSIs and IMSIs. When a TMSI is received with an LAI that does not correspond

to the current VLR, the IMSI of the MS must be requested from the VLR in charge of the

indicated location area if its address is known; otherwise the IMSI is requested from the MS.

A new TMSI must be allocated in each location updating procedure. The allocation of a new

TMSI corresponds implicitly for the mobile to the de-allocation of the previous one. In the

fixed part of the network, the cancellation of the record for an MS in VLR implies the deal

location of the corresponding TMSI. When a new TMSI is allocated to an MS, it is

transmitted to the MS in a ciphered mode. The MS stores its current TMSI in a non-volatile

memory together with the LAI so that these data are not lost when the MS is switched off.


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7.3 GPRS Authentication

The GPRS authentication procedure is handled in the same way as in GSM with the

distinction that the procedures are executed in the SGSN. In some cases, the SGSN requests

the pairs for a MS from the HLR/AUC corresponding to the IMSI of the MS.

7.4 GSM confidentiality

The signaling information elements related to the user, such as IMSI, and Calling

subscriber directory number (mobile terminated or originated calls) need to be protected after

connection establishment. The user information such as short messages is transferred in a

connectionless packet mode over a signaling channel. It should be protected. And also User

information on Physical Connections (voice and non-voice communications) on traffic

channels over the radio interface should be protected. In order to achieve that confidentiality,

a ciphering method, key setting, the starting of the enciphering and deciphering processes and

synchronization are needed.

A key setting completes a process that allows the MS and the network to agree on the

key Kc using in the ciphering and deciphering algorithms .It is triggered by the authentication

procedure and initiated by the network. Key setting must occur on a DCCH not yet encryptedand soon after the identity of the mobile subscriber is known by the network.

The transmission of Kc to the MS is indirect. A Kc is generated on both sides using

the key generator algorithm A8 and the authentication process. At the network side, the

values of Kc are calculated in the AUC/HLR. At the MS side, the Kc is stored by the mobile

station until it is updated at the next authentication. The encryption of signaling and user data

is performed at the MS as well as at the BSS. This is a case called symmetric encryption, i.e.

ciphering and deciphering are performed with the same Kc and the A5 algorithm and start on

DCCH and TCH. This process can be described as follows: First, the network (i.e. BSS)

requests the MS to start its (de)ciphering process and starts its own deciphering process. The

MS then starts its ciphering and deciphering. The first ciphered message from the MS, which

reaches the network and is correctly ciphered leads to the start of the ciphering process on the

network sides. The enciphering stream at one end and deciphering stream at the other end

must be synchronized. GPRS confidentiality GPRS network still needs this security feature.

However the ciphering scope is different. The scope of GSM is between BTS and MS. The


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scope of GPRS is from the SGSN to the MS. A new ciphering algorithm GPRS-A5 is used

because of the nature of GPRS traffic. The ciphering is done in the Logical Link Control

(LLC) layer. The GPRS-Kc is handled by the SGSN independently from MSC.


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Chapter 8

GPRS CHARGING AND BILLING TECHNIQUES

As packet data is introduced into mobile systems, the question of how to bill for the

services arises. Always online and paying by the minute does not sound all that appealing.

Here, we describe the possibilities but it is totally depends on different service providers how

they want to charge their customers:

The SGSN and GGSN register all possible aspects of a GPRS user's behavior and

generate billing information accordingly. This information is gathered in so-called Charging

Data Records (CDR) and is delivered to a billing gateway.

The GPRS service charging can be based on the following parameters:

Volume: The amount of bytes transferred i.e. downloaded and uploaded. Duration: The duration of a PDP context session. Time: Date, time of day, and day of the week (enabling lower tariffs at off peak

hours).

Final destination: A subscriber could be charged for access to the specific network,such as through a proxy server.

Location The current location of the subscriber. Quality of Service: Pay more for higher network priority. SMS: The SGSN will produce specific CDRs for SMS. Served IMSI/subscriber: Different subscriber classes (different tariffs for frequent

users, businesses, or private users).

Reverse charging: The receiving subscriber is not charged for the received data;instead, the sending party is charged.

Free of charge: Specified data to be free of charge. Flat rate: A fixed monthly fee. Bearer service: Charging based on different bearer services (for an operator who has

several networks, such as GSM900 and GSM1800, and who wants to promote usage

of one of the networks). Or, perhaps the bearer service would be good for areas where

it would be cheaper for the operator to offer services from a wireless LAN rather than

from the GSM network.


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Chapter 9

LIMITATIONS/ PROBLEMS REGUARDING GPRS TECHNOLOGY

Although GPRS has many benefits there have been a few problems. Connection

speeds until the end of last year performed badly on some networks running at around

12Kbps, a far cry from the expected. This year however there do not seem to be as many

problems, probably due to the fact that operators are improving due to trial and error. GPRS

is after all a pretty new technology.

Another problem sometimes encountered is customer expectation. Many companies

have applications running on a 10 megabyte LAN and expect the same performance from

their GPRS devices. Although the connection speeds these days are pretty good it still is not

as fast as ISDN or Local Area Networks. To a certain extent operators have themselves to

blame for this, since in the past their marketing has tended to promote the speed aspects of

2.5 and 3G. Today, they are working hard to reduce expectation in this respect.

Earlier problems with things like mail servers not sending mail because of latency

problems to GPRS devices have all been pretty much eradicated through optimization

programs. People running Citrix Thin Client has also encountered problems with latency

although a few Thin Client forums suggest that Citrix are addressing the issue.

Deployment on some networks has been slow. There still is a major UK network

provider who does not offer the service.

GPRS roaming has not been implemented in many countries on a lot of networks as

yet. This is where a user can use the GPRS service from any network operator. At the

moment although your GSM mobile will work, GPRS may not work at all. Accesses by third

party application providers are having a lot of difficulty obtaining an APN from providers to

offer their own GPRS services. This somewhat limits services to that provided by the GPRS

operator.


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Chapter 10

GPRS APPLICATIONS

GPRS will enable a variety of new and unique services to the mobile wireless

subscriber. These mobile applications contain several unique characteristics that enhance the

value to the customers. First among them is mobility, the ability to maintain constant voice

and data communications while on the move. Second is immediacy, which allows subscribers

to obtain connectivity when needed, regardless of location and without a lengthy login

session. Finally, localization allows subscribers to obtain information relevant to their current

location.

Communications

Communications applications include all those in which it appears to the users that

they are using the mobile communications network purely as a pipe to access messages or

information.

Intranet Access

The first stage of enabling users to maintain contact with their office is through access

to e-mail, fax, and voice mail using unified messaging systems. Increasingly, files and data

on corporate networks are becoming accessible through corporate intranets that can be

protected through firewalls, by enabling secure tunnels.

Internet Access

As a critical mass of users is approached, more and more applications aimed at

general consumers are being placed on the Internet. The Internet is becoming an invaluable

tool for accessing corporate data as well as for the provision of product and service

information. More recently, companies have begun using the Internet as an environment for

carrying out business, through e-commerce.


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E-Mail and Fax

E-mail on mobile networks may take one of two forms. It is possible for e-mail to be

sent to a mobile user directly, or users can have an e-mail account maintained by their

network operator or their Internet service provider (ISP).

Unified Messaging

Unified messaging uses a single mailbox for all messages, including voice mail,

faxes, email, short message service (SMS), and pager messages. With the various mailboxes

in one place, unified messaging systems then allow for a variety of access methods to recover

messages of different types. Some will use text-to-voice systems to read e-mail and, less

commonly, faxes over a normal phone line, while most will allow the interrogation of the

contents of the various mailboxes through data access, such as the Internet. Others may be

configured to alert the user on the terminal type of their choice when messages are received.

Value-Added Services

Value-added services refer strictly to content provided by network operators to

increase the value of their service to their subscribers.

E-Commerce

E-commerce is defined as the carrying out of business on the Internet or data service.

This would include only those applications where a contract is established over the data

connection, such as for the purchase of goods, or services, as well as online banking

applications because of the similar requirements of user authentication and secure

transmission of sensitive data.

Banking

Specific banking functions that can be accomplished over a wireless connection

include balance checking, moving money between accounts, bill payment, and overdraft

alert.


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Location-Based Services

Location-based services provide the ability to link push or pull information services

with a users location. Examples include hotel and restaurant finders, roadside assistance, an d

city-specific news and information.

Advertising

Advertising may be offered to customers to subsidize the cost of voice or other

information services. Advertising may be location sensitive where, for example, a user

entering a mall would receive advertising specific to the stores in that mall.


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Chapter 11

CONCLUSION

In summary, GPRS presents an intermediate step in bring high speed Internet access

to GSM users as the industry moves towards implementing 3rd Generation mobile services,

known as UMTS (Universal Mobile Telephone Service). GPRS will thrive in both vertical

and horizontal markets where high-speed data transmission over wireless networks is

required. The deployment of GPRS networks will enable a plethora of new applications

ranging from mobile e-commerce to mobile corporate VPN access. Deployment of GPRS

will also have a great impact on the wireless data traffic volume by generating new sources of

revenue for the service providers, especially since any current GSM network user can

upgrade services to include high-speed data. The only question is how soon it takes off in

earnest and how to ensure that the technical and commercial features do not hinder its

widespread use.


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GLOSSARY

2G Second generation; generic name for second generation of digital

mobile networks (such as GSM, and so on)

3G Third generation; generic name for next-generation mobile networks

(Universal Mobile Telecommunications System [UMTS], IMT-2000)

BG Border gateway

BGP Border Gateway Protocol

BSC Base Station Controller

BTS Base transceiver station

CS Circuit switched

DCCH Dedicated control channel

DHCP Dynamic Host Configuration Protocol

DNS Domain Name System EDGE Enhanced data rates for GSM evolution;

upgrade to GPRS systems that require new base stations and claims to

increase bandwidth to 384 kbps

EIR Equipment Identity Register

GGSN Gateway GPRS Support Node

Gi Reference point between GPRS and an external packet data network

Gn Interface between two GSNs within the same PLMN

Gp Interface between two GSNs in different PLMNs

GPRS General Packet Radio Service; upgrade to existing 2G digital mobile

networks to provide higher-speed data services

GSM Global System for Mobile Communications; most widely deployed 2G

digital cellular mobile network standard

GSN GPRS Support Node (xGSN)


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GTP GPRS Tunneling Protocol

GW Gateway

HDLC High-Level Data Link Control

HLR Home location register

HSCSD High-speed circuit-switched data; software upgrade for cellular

networks that gives each subscriber 56K data

IMSI International Mobile Subscriber Index

IP Internet Protocol

ISP Internet service provider

LA Local Area

LLC Logical Link Control

MAC Medium Access Control

MM Mobility management

MS Mobile station

MSC Mobile services switching center

NAS Network access server

PCU Packet control unit

PDA Personal digital assistant

PDN Packet data network

PDP Packet Data Protocol

PLMN Public Land Mobile Network; generic name for all mobile wireless

networks that use earth base stations rather than satellites;

PSPDN Packet Switched Public Data Network


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PSTN Public Switched Telephone Network

PVC Permanent virtual circuit

QoS Quality of service

RADIUS Remote Authentication Dial-In User Service RLP Radio Link Protocol

SGSN Serving GPRS Support Node

SLA Service-level agreement

SMS Short message service

SMSC Short message service center

TCP Transmission Control Protocol

TCH Traffic channel

TE Terminal equipment

TDMA Time Division Multiple Access

TMSI Temporary Mobile Subscriber Index

TS Time slot

Um Interface between the MS and the GPRS fixed network part

UMTS Universal Mobile Telecommunications System

VAS Value-added services

VLR Visitor locations register

VPN Virtual private network

WAP Wireless access Protocol; important protocol stack (Layers 4 through 7

of the OSImodel), used to send simplified Web pages to wireless

devices; uses IP but replaces TCP and Hypertext Transfer Protocol

(HTTP) with UDP and WTP, and requires pages to be written in

WML rather than in HTML


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Reference

[1] http://www.cisco.com/warp/public/cc/so/neso/gprs/index.shtml 14-05-13 and 11.10PM

[2] http://cserg0.site.uottawa.ca/ftp/pub/Lotos/Papers/GPRS_Tutorial.pdf 14-05-13and

11.25PM

[3]http://www.docstore.mik.ua/univercd/cc/td/doc/product/wireless/moblwrls/cmx/mmg_sg/c

mxgsm.htm15-05-13 and 8.15AM

[4]http://www.etsi.org/deliver/etsi_ts/101300_101399/101393/06.03.00_60/ts_101393v06030

0p.pdf 14-05-13 and 11:45PM

[5] http://www.tutorialspoint.com/gprs/index.htm 14-0513 and 9.30PM

[6] End-to-End Quality of Service over Cellular Networks by G. Gmez and R. Snchez

(page-18 to 30)

[7]http://etutorials.org/Mobile+devices/gprs+mobile+internet/Chapter+7+Signaling+Plane/P

DP+Context+Management/ 16-05-13 and 11.30AM

[8] http://www.docstoc.com/docs/134476048/General-Packet-Radio-Service-GPRS 16-05-13

and 2:30PM

[9]http://www.cs.colorado.edu/~rhan/CSCI_7143_002_Fall_2001/Papers/CAI97_GeneralPac

ketRadioSystem.pdf 16-05-13 and 4:00PM

[10] http://services.eng.uts.edu.au/userpages/kumbes/public_html/ra/gprs/gprs02a.htm 15-05-

2013 and 11:12PM

[11] http://www.hjortskov.dk/apparater.dk/maindoc/node23.html 16-05-2013 and 10:00PM

[12] http://www.gsmworld.com/technology/gprs/intro.shtml 17-05-13 and 9:00PM

[13] http://www.webopedia.com/TERM/G/GPRS.html 17-05-13 and 10:00PM

[14] http://www.ee.oulu.fi/~fiat/gprs.html 17-05-13 and 10:30PM

[15] GSM, GPRS AND EDGE Performance Edited by Timo Halonen and Javier Romero and

Juan Melero from Second Edition (page 14-47)

gprs full report

Documents