144908697-gprs-full-report.docx

1

Seminar Report On General Packet Radio Service (GPRS) Course Title: Seminar Course No.: ECE 4204 Submitted By

Submitted To

Group No-09

Sehrish Khan

A. K. M. Tohidur Rahman

Associate Professor

Student ID: 090918

ECE Discipline

S. M. M. Hossain Mahmud

Khulna University

Student ID: 090924

Khulna-9208

Tapan Kumar Biswas

&

Student ID: 090933

Dr. Md. Sohel Mahmud Sher

4th Year, 2nd Term

Associate Professor

ECE Discipline

ECE Discipline

Khulna University

Khulna University

Khulna-9208

Khulna-9208 Date of Submission: 28-05-2013

Khulna University Electronics and Communication Engineering Discipline Khulna-9208

2

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.

3

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 packetswitching 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 packetswitched 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.

4

TABLE OF CONTENTS Pages

Chapters

Topics

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

1.2.2

Second Generation Wireless Technology

7

1.2.3

Second 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

5

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

6

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

7

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

8

(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.

9

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.

10

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

11

 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

12

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 Support Like 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 higherbandwidth applications (such as multimedia Web content) not suited to slower GSM dial-up connections. GPRS is particularly well suited for applications based on the Wireless Application 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 and reassembled at the receiving end. Packet switching is similar to a jigsaw puzzle- the image

13

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

Table 1: Circuit switching vs. Packet switching Circuit Switching Packet Switching

Need to establish a Connection

Yes

No

Dedicated Path

Yes

No

Bandwidth allocation

Fixed

Dynamic

Potentially wasted bandwidth

Yes

No

Same path for all data

Yes

No

Congestion can occur at

Setup time

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.

14

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.

15

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 packetswitched 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 the GPRS network. The selection is done manually and there are no simultaneous operations.

16

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 user’s home system of the new location so that calls can be delivered. BTS R/S

Um

Packet network PSTN

BSC

MSC HLR/AuC

Gb

Packet Inter-PLMN network Backbone network

Serving GPRS Support Node Gn (SGSN) Border Gateway (BG) Intra-PLMN backbone network (IP based) Gp Firewall Point-ToMultipoint Service Center (PTM SC)

Gn

Gr

Gs

Gr

Gd Packet SS7 network Network

Gs GPRS INFRASTRUCTURE

EIR

Corporate 1 Server

MAP-F Router

Gateway GPRS Support Node (GGSN)

Firewall

Gi.IP

Data Packet network network (Internet)

Gi.X.25 Firewall

SMS-GMSC Gd

Data Packet network network (X.25)

Local area network

Corporate 2 Server

Router

Local area network

Figure 01: Functional View of GPRS Architecture [6] Many registers are also maintained which contain information necessary for the smooth functioning of the network. The HLR (Home Location Register) stores information

17

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 subnetwork-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.

18

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 network with GPRS.

Figure 02: Logical architecture description with the interfaces and reference points of

theGSM network with GPRS [6]

19

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 traffic and signaling between the GSM radio network (BSS) and the GPRS part. Frame relay–based network services (NSs) provide flow control for this interface.  Gc between the GGSN and the HLR. The GGSN may request location information for network 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 an SGSN. The Gd interface allows more efficient use of the SMS services.  Gf between an SGSN and the Equipment Identity Register (EIR). The Gf gives the SGSN 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 signaling interface 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 same functionality 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 subscriber information 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 or receive 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 interface for 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

20

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 to external 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 connects terminal 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: Table 2: Modifications on GSM Network GSM Network

Modification or Upgrade Required for GPRS

Element 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,

All the databases involved in the network will require software

HLR and so on)

upgrades to handle the new call models and functions introduced by GPRS.

21

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 GPRSspecific 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

Figure 03: GPRS Protocol Architecture [15]

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.

22

 The modulation of the transmitted waveforms and the raw data rates of GSM channels. Note that in the GPRS Rel’97 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. • The physical link layer provides 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 of transmitted 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 TDMA frames, as specified in.  Procedures for detecting physical link congestion. The physical link layer control functions include  Synchronization procedures, including means for determining and adjusting the MS timing 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.

23

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 modes—the 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.

24

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 radiorelated 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]

25

Figure 05: Network protocols multiplex [15]

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.

26

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 subscriber’s 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

27

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 user’s 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 of the user’s 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: PDP context activation procedure [7]

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.

28

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 prepaid 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 networkinitiated message when the MS has roamed to another GPRS operator’s network (path 3). In these examples, the operator’s 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

29

over the inter-operator network to ensure service-level agreements (SLAs). The main benefits of the architecture are its flexibility, scalability, interoperability, and roaming.

Figure 07: Data Routing Procedure [1]

5.4Location Management The main task of location management is to keep track of the user’s 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 MS’s 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.

30

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.

31

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 MS changes 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]

32

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 .5millisecond 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 deallocated.

33

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 or more PDTCH. 2. The packet access grant channel (PAGCH) is used to allocate one or more PDTCH to a mobile station. 3. The packet paging channel (PPCH) is used by the BSS to find out the location of a mobile station (paging) prior to downlink packet transmission. 4. The packet notification channel (PNCH) is used to inform a mobile station of incoming PTM messages (multicast or group call).

34

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.) Table 3: Channel coding Scheme

Data Rates(Kbps)

CS-1

9.05

CS-2

13.4

CS-3

16.6

CS-4

21.4

35

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 subscriber’s 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. It’s 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.

36

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 encrypted and 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

37

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.

38

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.

39

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.

40

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.

41

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.

42

Location-Based Services Location-based services provide the ability to link push or pull information services with a user’s location. Examples include hotel and restaurant finders, roadside assistance, and 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.

43

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.

44

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)

45

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

46

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

WML rather than in HTML

requires pages to be written in

47

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. Gómez and R. Sánchez (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 15-052013 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)