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					GPRS


                                                INDEX
            Sr.no        Name                                    Page no.



                1. INTRODUCTION ……………………………………1

                    1.1 What is GPRS?
                    1.2 What does GPRS do?
                    1.3 Why GPRS?
                    1.4 Timescales for GPRS

                2. FEATURES OF GPRS ………………………………4

                    2.1 Key User Features of GPRS
                          2.1.1 Speed
                          2.1.2 Immediacy
                          2.1.3 New Applications, Better Applications
                          2.1.4 Service Access

                    2.2 Key Network Features of GPRS
                         2.2.1 Packet Switching
                         2.2.2 Spectrum Efficiency
                         2.2.3 Internet Aware
                         2.2.4 Supports TDMA and GSM

                3. GPRS Terminals…………………………………….7

                    3.1 GPRS Terminal Classes
                    3.2 Device Types

                4. GPRS Architecture …………………………………9

                    4.1GPRS Reference Architecture
                          4.1.1 GPRS Subscriber Terminals
                          4.1.2 GPRS BSS
                          4.1.3 GPRS Networks Node
                          4.1.4 GPRS Mobility Management
                5. How GPRS Works …………………………………..12

                    5.1 Radio Interface
                    5.2 Mobile Devices
                    5.3 GPRS Roaming
            `       5.4 GPRS Security
                    5.5 Network Connectivity
                           5.5.1 Internet
                           5.5.2 Leased Lines
                           5.5.3 Frame Relay


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               6. GPRS Data Communication ……………………….17

                    6.1 GPRS Service
                    6.2 Data Routing
                           6.2.1 Data Packet Routing
                    6.3 GPRS Mobility Management

               7. GPRS Solution ……………………………………….21

                    7.1 GGSN Overview
                    7.2 GGSN Applications
                          7.2.1 Standalone PLMN
                          7.2.2 WAP services in GPRS environment
                          7.2.3 FAX over GPRS
                          7.2.4 Corporate Voice and Data
                          7.2.5 Virtual Private Network Corporate Solutions

               8. GPRS Application …………………………………...25

                    8.1 Communications
                           8.1.1 Intranet Access
                           8.1.2 Internet Access
                           8.1.3 E-Mail and Fax
                           8.1.4 Unified Messaging
                    8.2 Value-Added Services
                           8.2.1 E-Commerce
                           8.2.2 Banking
                           8.2.3 Financial Trading
                    8.3 Location-Based Services and Telematics
                    8.4 Vertical Applications
                    8.5 Advertising

               9. Limitations of GPRS ………………………………...29

                    9.1 Limited Cell Capacity for All Users
                    9.2 Speeds Much Lower in Reality
                    9.3 Support of GPRS Mobile Terminate by Terminals is Not Ensured
                    9.4 Suboptimal Modulation
                    9.5 Transit Delays
                    9.6 No Store and Forward

               10. Related GPRS Challenges ………………………..32

                    10.1 Billing
                    10.2 Tariffing
                      10.3 Customer Service

               11. GLOSSARY & REFERENCES …………………....35



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               INTRODUCTION : -

                    The name, General Packet Radio Service (GPRS) doesn't convey much
            information to the non-technical user. Describing it as providing a direct link into the
            Internet from a GSM phone, is much clearer. GPRS is to mobile networks what
            ADSL (Asymmetric Digital Subscriber Line) is to fixed telephone networks - the
            favoured solution for providing fast and inexpensive Internet links.

                    GPRS will undoubtedly speed up a handset's Internet connection - but it
            remains to be seen exactly how much speed can be wrung out of the system. GPRS
            works by amalgamating (aggregating) a number of separate data channels. This is
            feasible because data is being broken down into small 'packets' which are re-
            assembled by the receiving handset back into their original format. The catch is that
            the number of receiving channels does not necessarily have to match the number of
            sending channels. On the Internet, it is assumed that you want to view more
            information (such as a complicated Web page) than you want to send (such as a
            simple Yes or No response). So GPRS is an asymmetric technology because the
            number of ‘down’ channels used to receive data doesn’t match the number of ‘up’
            channels used to send data.

                    The task of defining GPRS has been the responsibility of the Special Mobile
            Group (SMG) - part of the 3GPP initiative (3rd Generation Partnership Project).
            Rather than wait for the final version of the SMG standard some manufacturers
            decided to go with GPRS handsets which conformed to an earlier version of the
            specifications known as SMG29. This basically offers two 'down' channels and a
            single 'up' channel. In practice each channel is offering around 12-13 Kbit/s so the top
            speeds works out to be around 26 Kbit/s. Most experts agree, however that full
            interoperability between products will come with SMG 31. This is capable of offering
            four 'down' channels which equates to a top speed of around 52 Kbit/s - the same as a
            high speed (V.90) landline modem.

                    GPRS is classified as a 2.5G (or 2G Plus) technology because it builds upon
            existing network infrastructure whereas with 3G networks it normally requires
            building an entirely new network. In order to compete against 3G networks, therefore,
            North- American operators have been looking to GPRS to provide high speed data
            links. Hence, manufacturers have been working on a related technology known as
            EDGE (Enhanced Data for Global Evolution). In order to compete with 3G, EDGE
            must offer links running at 384 Kbit/s and originally this equated to running GPRS
            three times faster. However, because GPRS has proved much slower than expected, it
            now needs to be seven times faster.




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            WHAT IS GPRS?
                    GPRS stands for General Packet Radio Service, and is a relatively low cost
            technology that offers packet-based radio service and allows data or information to be
            sent and received across mobile telephone networks.Designed to supplement the
            existing mobile technologies, like GSM, CDMA, and TDMA etc.

            WHAT DOES GPRS DO?
                    GPRS provides a permanent connection where information can be sent or
            received immediately as the need arises, subject to radio coverage. No dial-up modem
            connection is necessary. This is why GPRS users are sometimes referred to be as
            being anytime-anywhere "always connected".The GPRS tariff structure is based on a
            fixed cost, dependent on the quantity of data required. In other words customers will
            be able to fix their operating costs without the concerns of variable billing.

            WHY GPRS?
                    At present circuit switching technique like your telephone line, in order to
            send or receive emails, transfer files or browse WAP/Web sites.it is first necessary to
            make a 'data' call. The call is answered by a modem or an ISDN adapter owned either
            by the network operator itself (such as BT Cellnet) or by an Internet Service Provider
            (ISP). Next the caller is 'authenticated' by giving a user ID and password and then
            assigned an Internet address by the ISP or operator. The whole process can take up to
            sixty seconds or more and even at the end of this procedure the connection is slow -
            normally a mere 9.6 Kbit/s.
                    With packet switching technique GPRS, there is no call. Once the handset is
            powered on, by pressing a button the user is connected directly to the Internet. The
            link is only broken when the handset is turned off - hence GPRS is known as an
            'always on' connection. The fact that the link is continuous has one major benefit. It
            enables the ISP/operator to know a handset's Internet address. So messages can be
            passed directly over the Internet from a PC, for example, down to your handset.
            Crucially this facility enables the Internet Service Provider to 'push' messages down to
            your handset - rather like an SMS message. The difference is that with GPRS the link
            is interactive. That means if you want to respond directly - such as instruct your
            broker to sell 500 shares - you can. One of the major criticisms aimed at WAP is that
            it lacked support for 'push' technologies. This failing has effectively been rectified via
            an update to the WAP standards (version 1.2) and the introduction of GPRS enabled
            WAP handsets.

            TIMESCALES FOR GPRS :
                    When a new service is introduced, there are a number of stages before it
            becomes established. GPRS service developments will include standardization,
            infrastructure development, network trials, contracts placed, network roll out,
            availability of terminals, application development, and so on. These stages for GPRS
            are:




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                            Date                                       Milestone
            Throughout 1999 – 2000                    Network operators place trial and
                                                      commercial contracts for GPRS
                                                      infrastructure.
                                                      Incorporation of GPRS infrastructure into
                                                      GSM networks
            Summer of 2000                            First trial GPRS services become
                                                      available. Typical single user throughput
                                                      is likely to be 28 kbps.
                                                      For example, T-Mobil is planning a
                                                      GPRS trial at Expo2000 in Hanover in the
                                                      Summer of 2000
            Start of 2001                             Basic GPRS capable terminals begin to
                                                      be available in commercial quantities
            Throughout 2001                           Network operators launch GPRS services
                                                      commercially and roll out GPRS.
                                                      Vertical market and executive GPRS
                                                      early adopters begin using it regularly for
                                                      nonvoice mobile communications
            2001/2                                    Typical single user throughput is likely to
                                                      be 56 kbps. New GPRS specific
                                                      applications, higher bitrates, greater
                                                      network capacity solutions, more capable
                                                      terminals become available, fuelling
                                                      GPRS usage
            2002                                      Typical single user throughput is likely to
                                                      be 112 kbps.
                                                      GPRS Phase 2/ EDGE begins to emerge
                                                      in practice
            2002/3                                    3GSM arrives commercially

                   Like the GSM standard itself, GPRS will be introduced in phases. Phase 1 is
            expected to be available commercially in the year 2000/1. Point to Point GPRS
            (sending information to a single GPRS user) will be supported, but not Point to
            Multipoint (sending the same information to several GPRS users at the same time).
            GPRS Phase 2 is not yet fully defined, but is expected to support higher data rates
            through the possible incorporation of techniques such as EDGE (Enhanced Data rates
            for GSM Evolution), in addition to Point-to-Multipoint support.




TheDirectData.com                                                                                   Page 5
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            2. FEATURES OF GPRS
            2.1 KEY USER FEATURES OF GPRS :

                    The General Packet Radio Service (GPRS) is a new nonvoice value added
            service that allows information to be sent and received across a mobile telephone
            network. It supplements today's Circuit Switched Data and Short Message Service.
            GPRS is NOT related to GPS (the Global Positioning System), a similar acronym that
            is often used in mobile contexts. GPRS has several unique features which can be
            summarized as:
            SPEED:
                    Theoretical maximum speeds of up to 171.2 kilobits per second (kbps) are
            achievable with GPRS using all eight timeslots at the same time. 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. By allowing information to be transmitted more quickly,
            immediately and efficiently across the mobile network, GPRS may well be a
            relatively less costly mobile data service compared to SMS and Circuit Switched
            Data.
            IMMEDIACY:

                   GPRS facilitates instant connections whereby information can be sent or
            received immediately as the need arises, subject to radio coverage. No dial-up modem
            connection is necessary. This is why GPRS users are sometimes referred to be as
            being "always connected". Immediacy is one of the advantages of GPRS (and SMS)
            when compared to Circuit Switched Data. High immediacy is a very important feature
            for time critical applications such as remote credit card authorization where it would
            be unacceptable to keep the customer waiting for even thirty extra seconds.

            NEW APPLICATIONS, BETTER APPLICATIONS:

                     GPRS facilitates several new applications that have not previously been
            available over GSM networks due to the limitations in speed of Circuit Switched Data
            (9.6 kbps) and message length of the Short Message Service (160 characters). GPRS
            will fully enable the Internet applications you are used to on your desktop from web
            browsing to chat over the mobile network. Other new applications for GPRS, profiled
            later, include file transfer and home automation- the ability to remotely access and
            control in-house appliances and machines.

            SERVICE ACCESS :

            To use GPRS, users specifically need:

                   A mobile phone or terminal that supports GPRS (existing GSM phones do
                    NOT support GPRS)
                   A subscription to a mobile telephone network that supports GPRS



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                   Use of GPRS must be enabled for that user. Automatic access to the GPRS
                    may be allowed by some mobile network operators, others will require a
                    specific opt-in
                   Knowledge of how to send and/ or receive GPRS information using their
                    specific model of mobile phone, including software and hardware
                    configuration (this creates a customer service requirement)
                   A destination to send or receive information through GPRS. Whereas with
                    SMS this was often another mobile phone, in the case of GPRS, it is likely to
                    be an Internet address, since GPRS is designed to make the Internet fully
                    available to mobile users for the first time. From day one, GPRS users can
                    access any web page or other Internet applications- providing an immediate
                    critical mass of uses.

            2.2 KEY NETWORK FEATURES OF GPRS :

            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. To supplement a circuit switched network architecture with packet switching
            is quite a major upgrade. However, as we shall see later, the GPRS standard is
            delivered in a very elegant manner- with network operators needing only to add a
            couple of new infrastructure nodes and making a software upgrade to some existing
            network elements.

                    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 jigsaw puzzle- the image 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. The Internet itself is another example of a packet data network,
            the most famous of many such network types.

            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.



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            GPRS should improve the peak time capacity of a GSM network since it
            simultaneously allocates scarce radio resources more efficiently by supporting virtual
            connectivity immigrates traffic that was previously sent using Circuit Switched Data
            to GPRS instead, and reduces SMS Center and signaling channel loading by
            migrating some traffic that previously was sent using SMS to GPRS instead using the
            GPRS/ SMS interconnect that is supported by the GPRS standards.

            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.

                    The World Wide Web is becoming the primary communications interface-
            people access the Internet for entertainment and information collection, the intranet
            for accessing company information and connecting with colleagues and the extranet
            for accessing customers and suppliers. These are all derivatives of the World Wide
            Web aimed at connecting different communities of interest. There is a trend away
            from storing information locally in specific software packages on PCs to remotely on
            the Internet. When you want to check your schedule or contacts, instead of using
            something like "Act!", you go onto the Internet site such as a portal. Hence, web
            browsing is a very important application for GPRS.

            Because it uses the same protocols, the GPRS network can be viewed as a sub-
            network of the Internet with GPRS capable mobile phones being viewed as mobile
            hosts. This means that each GPRS terminal can potentially have its own IP address
            and will be addressable as such.

            SUPPORTS TDMA AND GSM :

                    It should be noted right that the General Packet Radio Service is not only a
            service designed to be deployed on mobile networks that are based on the GSM
            digital mobile phone standard. The IS-136 Time Division Multiple Access (TDMA)
            standard, popular in North and South America, will also support GPRS. This follows
            an agreement to follow the same evolution path towards third generation mobile
            phone networks concluded in early 1999 by the industry associations that support
            these two network types.




            3       GPRS TERMINALS :-
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                    A complete understanding of the application availability and GPRS timeline
            requires understanding of terminal types and availability. The term "terminal
            equipment" is generally used to refer to the variety of mobile phones and mobile
            stations that can be used in a GPRS environment; the equipment is defined by
            terminal classes and types. Cisco Gateway GPRS Serving Node (GGSN) and data
            network components interoperate with GPRS terminals that follow the GPRS
            standards.

            GPRS TERMINAL CLASSES :
                   A GPRS terminal can be one of three classes: A, B, or C. A Class A terminal
            supports GPRS and other GSM services (such as SMS and voice) simultaneously.
            This support includes simultaneous attach, activation, monitor, and traffic. As such, a
            Class A terminal can make or receive calls on two services simultaneously. In the
            presence of circuit-switched services, GPRS virtual circuits will be held or placed on
            busy rather than being cleared.

                     A Class B terminal can monitor GSM and GPRS channels simultaneously, but
            can support only one of these services at a time. Therefore, a Class B terminal can
            support simultaneous attach, activation, and monitor, but not simultaneous traffic. As
            with Class A, the GPRS virtual circuits will not be closed down when circuit-switched
            traffic is present. Instead, they will be switched to busy or held mode. Thus, users can
            make or receive calls on either a packet or a switched call type sequentially, but not
            simultaneously.

                    A Class C terminal supports only nonsimultaneous attach. The user must
            select which service to connect to. Therefore, a Class C terminal can make or receive
            calls from only the manually (or default) selected service. The service that is not
            selected is not reachable. Finally, the GPRS specifications state that support of SMS
            is optional for Class C terminals.

            DEVICE TYPES :
                   In addition to the three variables, each handset will have a unique form factor.
            Some of the form factors will be similar to current mobile wireless devices, while
            others will evolve to use the enhanced data capabilities of GPRS.

                    The earliest available type will be closely related to the current mobile phone.
            These will be available in the standard form factor with a numeric keypad and a
            relatively small display.

                    PC Cards are credit card-sized hardware devices that connect via a serial cable
            to the bottom of a mobile phone. Data cards for GPRS phones will enable laptops and
            other devices with PC Card slots to be connected to mobile GPRS-capable phones.
            Card phones provide functionality similar to that offered by PC Cards, without
            needing a separate phone. These devices may need an earpiece and microphone to
            support voice services.

                   Smart phones are mobile phones with built-in voice, nonvoice, and Web-
            browsing services. Smart phones integrate mobile computing and mobile
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            communications into a single terminal. They come in various form factors, which may
            include a keyboard or an icon drive screen. The Nokia 9000 series is a popular
            example of this form factor.

                    The increase in machine-to-machine communications has led to the adoption
            of application-specific devices. These "black-box" devices lack a display, keypad, and
            voice accessories of a standard phone. Communication is accomplished through a
            serial cable. Applications such as meter reading utilize such black-box devices.

                    Personal digital assistants (PDAs) such as the Palm Pilot series or Handspring
            Visor are data-centric devices that are adding mobile wireless access. These devices
            can either connect with a GPRS-capable mobile phone via a serial cable or have GPRS
            capability built in.




            4       GPRS ARCHITECTURE : -

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                   From a high level, GPRS can be thought of as an overlay network onto 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.

                   GPRS attempts to reuse the existing GSM network elements as much as
            possible, but in order to effectively build a packet-based mobile cellular network,
            some new network elements, interfaces, and protocols that handle packet traffic are
            required. Therefore, GPRS requires modifications to numerous network elements, as
            summarized in following Table and illustrated in following Figure.




            MODIFICATIONS REQUIRED FOR GPRS :

            GSM Network        Modification or Upgrade Required for GPRS
            Element

            Subscriber         A totally new subscriber terminal is required to access GPRS
            Terminal (TE)      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          All the databases involved in the network will require software
            (VLR, HLR,         upgrades to handle the new call models and functions introduced
            and so on)         by GPRS.




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            GPRS REFERENCE ARCHITECTURE :
                    Generic GPRS Network Architecture




            GPRS SUBSCRIBER TERMINALS :

                    New terminals (TEs) are required because existing GSM phones do not handle
            the enhanced air interface, nor do they have the ability to packetize traffic directly. A
            variety of terminals will exist, as described in a previous section, including a high-
            speed version of current phones to support high-speed data access, a new kind of PDA
            device with an embedded GSM phone, and PC Cards for laptop computers. All these
            TEs will be backward compatible with GSM for making voice calls using GSM.

            GPRS BSS :

                    Each BSC will require the installation of one or more PCUs and a software
            upgrade. The PCU provides a physical and logical data interface out of the base
            station system (BSS) for packet data traffic. The BTS may also require a software
            upgrade, but typically will not require hardware enhancements.

                    When either voice or data traffic is originated at the subscriber terminal, it is
            transported over the air interface to the BTS, and from the BTS to the BSC in the
            same way as a standard GSM call. However, at the output of the BSC the traffic is
            separated; voice is sent to the mobile switching center (MSC) per standard GSM, and
            data is sent to a new device called the SGSN, via the PCU over a Frame Relay
            interface.

            GPRS NETWORKS NODE :

                    In the core network, the existing MSCs are based upon circuit-switched
            central-office technology, and they cannot handle packet traffic. Thus two new
            components, called GPRS Support Nodes, are added:

                       Serving GPRS Support Node (SGSN)
                       Gateway GPRS Support Node (GGSN)

                   The SGSN can be viewed as a "packet-switched MSC;" it delivers packets to
            mobile stations (MSs) within its service area. SGSNs send queries to home location
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            registers (HLRs) to obtain profile data of GPRS subscribers. SGSNs detect new
            GPRS MSs in a given service area, process registration of new mobile subscribers,
            and keep a record of their location inside a given area. Therefore, the SGSN performs
            mobility management functions such as mobile subscriber attach/detach and location
            management. The SGSN is connected to the base-station subsystem via a Frame
            Relay connection to the PCU in the BSC.

                    GGSNs are used as interfaces to external IP networks such as the public
            Internet, other mobile service providers' GPRS services, or enterprise intranets.
            GGSNs maintain routing information that is necessary to tunnel the protocol data
            units (PDUs) to the SGSNs that service particular MSs. Other functions include
            network and subscriber screening and address mapping. One (or more) GGSNs may
            be provided to support multiple SGSNs. More detailed technical descriptions of the
            SGSN and GGSN are provided in a later section.

                    Enabling GPRS on a GSM network requires the addition of two core modules,
            the Gateway GPRS Service Node (GGSN) and the Serving GPRS Service Node
            (SGSN). As the word Gateway in its name suggests, the GGSN acts as a gateway
            between the GPRS network and Public Data Networks such as IP and X.25. GGSNs
            also connect to other GPRS networks to facilitate GPRS roaming. The Serving GPRS
            Support Node (SGSN) provides packet routing to and from the SGSN service area for
            all users in that service area.

                     In addition to adding multiple GPRS nodes and a GPRS backbone, some other
            technical changes that need to be added to a GSM network to implement a GPRS
            service. These include the addition of Packet Control Units; often hosted in the Base
            Station Subsystems, mobility management to locate the GPRS Mobile Station, a new
            air interface for packet traffic, new security features such as ciphering and new GPRS
            specific signalling.

            GPRS MOBILITY MANAGEMENT :

                     Mobility management within GPRS builds on the mechanisms used in GSM
            networks; as a MS moves from one area to another, mobility management functions
            are used to track its location within each mobile network. The SGSNs communicate
            with each other and update the user location. The MS profiles are preserved in the
            visitor location registers (VLRs) that are accessible by the SGSNs via the local GSM
            MSC. A logical link is established and maintained between the MS and the SGSN in
            each mobile network. At the end of transmission or when a MS moves out of the area
            of a specific SGSN, the logical link is released and the resources associated with it
            can be reallocated.

                   A final category of GPRS terminals is handheld communications. Again, these
            are primarily data-centric devices that are adding mobile wireless access. Access can
            be gained via a PC Card or via a serial cable to a GPRS-capable phone.




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            5       HOW GPRS WORKS : -
                    The General Packet Radio Service is Mobile Data upgrade to a GSM mobile
            phone network. This provides users with packet data services (similar to the Internet)
            using the GSM digital radio network. Each voice circuit in GSM transmits the speech
            on a secure 14kbps digital radio link between the mobile phone and a nearby GSM
            transceiver station. The GPRS service joins together multiple speech channels to
            provide higher bandwidth data connections for GPRS data users. The radio bandwidth
            remains the same, it is just shared between the voice users and the data users. The
            network operator has the choice of prioritizing one or the other.

                    GPRS users will also benefit from being able to use GPRS while traveling as
            the GSM system should transparently hand over the GPRS connection from one base
            station to another.

            RADIO INTERFACE :

                    Each GSM radio transceiver uses Time Division Multiplexing to deliver eight
            voice circuits on one radio channel. Each radio site may have one or more
            transceivers to provide sufficient channels to end users (maximum numbers are
            limited by many factors including - operators radio license, interference with other
            nearby GSM cells, cost of equipment, capacity of radio site infrastructure etc.)

                   A GPRS user may theoretically use all voice channels on one transceiver - (8 *
            14 kbps) but radios to support this are not available and the operators will probably
            reserve at least some channels for voice circuits.

                    Each 14kbps channel may be shared by multiple 'connected' GPRS users
            (many users will be connected to the network but transmitting very little data). As a
            user's data requirements grow, they will use more of the available capacity within that
            timeslot, and then more available timeslots up to the maximum available or the
            maximum supported by their device.




                    In general the higher the data rate, the more power the mobile device will use
            and the shorter the battery life and the higher the transmitted RF power. If you are
            using GPRS with a mobile phone, do not keep it near your ear for long periods while
            data transfers are taking place.



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            GPRS MOBILE DEVICES :

                    The key use for GPRS is to send and receive data to a computer application
            such as Email, web browsing or even telemetry (telemetry refers to devices not being
            controlled by humans such as cash point machines or traffic monitoring cameras etc.).
            To use GPRS the service is 'dialed' in a similar manner to a standard data call (though
            there is no phone no.) at which point the user is 'attached' and an IP address is
            allocated. From then on data can flow to and from the Internet until either the network
            unattaches you (maybe because of a time-out, fault or congestion) or you manually
            unattach.

                    Mobile workers usually have a mobile phone, when this includes GPRS then it
            can also be used to transfer data to an connected computer.

            Some of the key issues are:

                        Using GPRS will not stop you making or receiving voice calls.
                        Current phones will usually suspend the data session while a voice call
                         takes place.
                        Battery life will be reduced when using GPRS.
                        The data needs to be connected with your computer.

            The three standard methods to connect your computer to GPRS mobile phone
            are:

                        Infrared - available on most business mobile phones - just align the
                         IR. port on the phone with the IR. port on the Laptop
                        Data-cable - reliable and doesn't require the careful alignment of IR.
                         which may be difficult when traveling
                        Bluetooth - My preferred solution - often difficult to set up but once
                         its configured Bluetooth provides a very convenient connection.
                         Bluetooth is available for connecting to Laptops via USB, PC-cards or
                         CF-cards in addition to cards for PDAs such as those offered by
                         PALM. Older Compaq IPAQs will require an expansion jacket but
                         newer Pocket PC devices usually include a suitable expansion port
                         (check at the time of purchase). One very important point is that
                         Bluetooth devices are very low powered so do not drain your computer
                         battery or phone battery too much. Many people will be tempted by the
                         all-in-one phone/PDA, but consider will you be happy with the
                         relatively short battery life, large size and weight and unreliability of
                         many PocketPC devices.

            GPRS data cards are also available, the issues here are:

                          Fully integrated solution
                          Best in Laptops with PC card expansion slots
                          GPRS will drain your battery so expect reduced life
                          You can subscribe to a different network than your GSM voice
                           supplier


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                        GPRS data cards will have their own SIM card and hence will need
                         another subscription to your mobile network

            GPRS ROAMING :
                   In the short term don't expect to be able to roam to many countries with GPRS,
            many networks are still negotiating to set up roaming agreements. Technically there
            are two type of GPRS Roaming

                        Home Network Roaming - Here all data is transmitted from wherever
                         you connect to a GPRS network to your home GPRS network where it
                         is connected to the Internet or your company LAN as if you were
                         indeed in your home country.
                        Local Network Roaming - Data is just connected to a local Internet
                         connection point and will be subject to local conditions for security
                         and performance.

                    GPRS users would be advised to ensure they also are able to use either GSM
            or High Speed GSM data (HSCSD) to retrieve their data when traveling because of
            the changing state of GPRS roaming agreements. They can either phone their ISP or
            RAS server on their home network or subscribe to an ISP which provides local access
            points in each country visited.

            GPRS SECURITY :

                   The radio interface is considered to be relatively secure being controlled by
            the GSM network's security - (SIM card + HLR). Security issues arise when data
            needs to leave the GPRS network to be delivered to either the Internet or a company
            LAN.

                    Internet connectivity is the cheapest and most common - and here you can take
            charge of security by encrypting sensitive data. If your GPRS network supplier allows
            it you can set up encrypted VPN connections to your company systems - though there
            could be a performance hit. Treat the connection as a standard dial-up Internet
            connection to an ISP and take similar security precautions.

            NETWORK CONNECTIVITY :

                   As a business GPRS user you will have a choice of methods to connect to the
            GPRS network - by far the most common method will be via the Internet. For larger
            users you may connect your company LAN to the GPRS networks using leased lines
            or Frame Relay virtual circuits.




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            INTERNET:

                   Your company probable already has an Internet connection (though you may
            need more capacity if you add many GPRS users) and this provides a quick and easy
            way of connection to GPRS.

                    The key problem is to deliver your data SECURELY to your users, using
            strong encryption such as with SSL (128 bit) or VPN (162 bit).

            For secure company Email access you have a number of choices. These include:

                        VPN firewalls - this will provide secure access to everything on the
                         company LAN from GPRS and other Internet users.
                        Microsoft Mobile Information Server
                        WAP interfaces to your Email system e.g. Peramon
                        POP server - set up a company POP server to provide Internet based
                         Email, make sure to enable additional security if required.

                    Employees (often senior managers) often bypass a companies security systems
            by redirecting to personal Internet Email accounts which provides them with a quick
            fix to mobile connectivity.

            LEASED LINES :

                    Leased lines provide the most secure method of connecting to GPRS but are
            traditionally expensive and have long contract periods. (Min 1 year)

                   The protocol over the leased line would normally be frame relay but it is
            possible you could use ATM with some networks. You do not really need any CPE
            (Customer Premises Equipment) supplied by your GPRS network supplier, just a
            spare Frame relay port on an existing router. There may be economies to be made if
            you also use the leased line to carry standard voice and data and bulk SMS in addition
            to the GPRS traffic - in which case your network supplier will provide a device to
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            route these onto your network. They may also try to sell you consultancy to design
            this interface - shop around to get the best solution.

                   Keep costs down by connecting to a geographically close connection point to
            the chosen GPRS network. Not all networks have the same number and location of
            connection points (GGSNs in GPRS terms).

            FRAME RELAY :

                    If you already have a frame relay connection with one of the key UK network
            suppliers then adding an addition PVC (Private Virtual Circuit) to one of the GPRS
            networks will make a cost effective solution, even if you have to increase the size of
            the link.

                   Ask your network supplier about availability figures as it is important they
            have redundant connections to the chosen Frame supplier.




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            6       GPRS DATA COMMUNICATION :-
                     Some cooperation still exists between elements of the current GSM services
            and GPRS. On the physical layer, resources can be reused and some common
            signaling issues exist. In the same radio carrier, there can be time slots (TSs) reserved
            simultaneously for circuit-switched and GPRS use. The most optimum resource
            utilization is obtained through dynamic sharing between circuit-switched and GPRS
            channels. During the establishment of a circuit-switched call, there is enough time to
            preempt the GPRS resources for circuit-switched calls that have higher priority.

            GPRS SERVICE :
                    The GPRS provides a bearer service from the edge of a data network to a
            GPRS MS. The GPRS protocol layering is illustrated in Figure shown below. The
            physical radio interface consists of a flexible number of TDMA time slots (from 1 to
            8) and thus provides a theoretical raw data rate of 171 kbps. A Media Access Control
            (MAC) utilizes the resources of the physical radio interface and provides a service to
            the GPRS Logical Link Control (LLC) protocol between the MS and the serving GSN
            (SGSN). LLC is a modification of a High-Level Data Link Control (HDLC)-based
            Radio Link Protocol (RLP) with variable frame size. The two most important features
            offered by LLC are the support of point-to-multipoint addressing and the control of
            data frame retransmission. From the standpoint of the application, GPRS provides a
            standard interface for the network layer.


            Figure : GPRS Protocol Layering




            DATA ROUTING :
                   One of the main issues in the GPRS network is the routing of data packets
            to/from a mobile user. The issue can be divided into two areas: data packet routing
            and mobility management.

            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


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            appropriate data network and collects charging data that is forwarded to a charging
            gateway.

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



            Figure : Routing of Data Packets between a Fixed Host and a GPRS MS




                    The GPRS network encapsulates all data network protocols into its own
            encapsulation protocol, called the GPRS Tunneling Protocol (GTP), as shown in
            above Figure. This is done to ensure security in the backbone network and to simplify
            the routing mechanism and the delivery of data over the GPRS network.

            GPRS MOBILITY MANAGEMENT :
                   The operation of the GPRS is partly independent of the GSM network.
            However, some procedures share the network elements with current GSM functions to
            increase efficiency and to make optimum use of free GSM resources (such as
            unallocated time slots).


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            Figure : States of GPRS in a Mobile Station




                    An MS has three states in the GPRS system: idle, standby, and active . The
            three-state model represents the nature of packet radio relative to the GSM two-state
            model (idle or active).

                    Data is transmitted between a MS and the GPRS network only when the MS is
            in the active state. In the active state, the SGSN knows the cell location of the MS.
            However, in the standby state, the location of the MS is known only as to which
            routing area it is in. (The routing area can consist of one or more cells within a GSM
            location area.)

                   When the SGSN sends a packet to a MS that is in the standby state, the MS
            must be paged. Because the SGSN knows the routing area in which the MS is located,
            a packet paging message is sent to that routing area. After receiving the packet paging
            message, the MS gives its cell location to the SGSN to establish the active state.

                    Packet transmission to an active MS is initiated by packet paging to notify the
            MS of an incoming data packet. The data transmission proceeds immediately after
            packet paging through the channel indicated by the paging message. The purpose of
            the packet paging message is to simplify the process of receiving packets. The MS has
            to listen to only the packet paging messages, instead of all the data packets in the
            downlink channels, reducing battery use significantly.

                    When an MS has a packet to be transmitted, access to the uplink channel is
            needed. The uplink channel is shared by a number of MSs, and its use is allocated by
            a BSS. The MS requests use of the channel in a packet random access message. The
            transmission of the packet random access message follows Slotted Aloha procedures.
            The BSS allocates an unused channel to the MS and sends a packet access grant
            message in reply to the packet random access message. The description of the channel
            (one or multiple time slots) is included in the packet access grant message. The data is
            transmitted on the reserved channels.

                    The main reasons for the standby state are to reduce the load in the GPRS
            network caused by cell-based routing update messages and to conserve the MS
            battery. When a MS is in the standby state, there is no need to inform the SGSN of
            every cell change—only of every routing area change. The operator can define the
            size of the routing area and, in this way, adjust the number of routing update
            messages.

                   In the idle state, the MS does not have a logical GPRS context activated or any
            Packet-Switched Public Data Network (PSPDN) addresses allocated. In this state, the
            MS can receive only those multicast messages that can be received by any GPRS MS.


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            Because the GPRS network infrastructure does not know the location of the MS, it is
            not possible to send messages to the MS from external data networks.

                    A cell-based routing update procedure is invoked when an active MS enters a
            new cell. In this case, the MS sends a short message containing information about its
            move (the message contains 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.

                    When an MS in an active or a standby state moves from one routing area to
            another in the service area of one SGSN, it must again 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.

                    The inter-SGSN routing update is the most complicated of the three routing
            updates. In this case, 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 SGSN, as well as informing the GGSN about the
            new location of the MS.




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            7       GPRS SOLUTION : -
                   The GGSN network element, while the SGSN solution is available through
             Cisco partners.

            GGSN OVERVIEW :
            GGSN combines in one box:

                     GGSN features as defined by the European Telecommunication Standards
                      Institute (ETSI)
                     Value-added networking functionality of Cisco routers

            The GGSN functionality embedded in the Cisco IOS® software is what differentiates
            the Cisco GGSN. The Cisco IOS software within a GGSN provides a sophisticated
            suite of networking capabilities that reside at the heart of internetworking devices.
            These capabilities provide interoperability with more standards-based physical and
            logical protocol interfaces than any other internetworking solutions. They connect
            otherwise-disparate hardware and provide security, reliability, and investment
            protection in the face of network growth, change, and new applications.

            The Cisco GGSN is compliant with ETSI's GPRS standards. Key GPRS features
            supported by GGSN include GPRS-defined routing and transfers, mobility
            management in conjunction with SGSN, GPRS quality-of-service (QoS) classes
            mapping to Internet QoS, QoS negotiation and handling, mobile authentication
            through Remote Authentication Dial-In User Service (RADIUS), dynamic IP
            addressing through Dynamic Host Configuration Protocol (DHCP), network
            management, and charging data collection. The Cisco GGSN supports all Cisco IOS
            features. A partial list of supported Cisco IOS features within GGSN includes IP
            routing, IP tunneling, and support of the Domain Name System (DNS), DHCP, and
            RADIUS. Additional technical information can be found in the Cisco GGSN data
            sheet.

            GGSN APPLICATIONS :
                    The GGSN can be deployed in a variety of network topologies and
            architectures. The following sections illustrate several alternatives.

            STANDALONE PLMN :

                    Operators of a standalone Public Land Mobile Network (PLMN) who own the
            frequency may have one or more SGSNs and GGSNs. The GGSN serves as a gateway
            to the Internet (external packet data network). (See in following Figure.)




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            Figure : The Cisco GPRS solution enables GSM operators to provide packet data
            service to their mobile subscribers.




            WAP SERVICES IN GPRS ENVIRONMENT :

                   The Wireless Access Protocol (WAP) empowers mobile users of wireless
            devices to easily access live interactive information services and applications from the
            screens of mobile phones. Services and applications include e-mail, customer care,
            call management, unified messaging, weather and traffic alerts, news, sports and
            information services, electronic commerce transactions and banking services, online
            address book and directory services, as well as corporate intranet applications.

                    WAP utilizes HTTP 1.1 Web servers to provide content on the Internet or
            intranets, thereby taking advantage of existing application development
            methodologies and developer skill sets such as CGI, ASP, NSAPI, JAVA, and
            Servlets. WAP defines an XML (eXtensible Markup Language) syntax called WML
            (Wireless Markup Language). All WML content is accessed over the Internet using
            standard HTTP 1.1 requests.

                    To take advantage of today's extremely large market penetration of mobile
            devices, the user interface components of WML map well onto existing mobile phone
            user interfaces. This means end users can immediately use WAP-enabled mobile
            phones and services without re-education. WAP specifications enable products which
            employ standard Internet technology to optimize content and airlink protocols to
            better suit the characteristics and limitations of existing and future wireless networks
            and devices. Since WAP transport is based on IP, Cisco can provide all the required
            features and products to scale mass market WAP applications.(see in following
            figure)




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            Figure : SN in a WAP enabled network




            FAX OVER GPRS :

                    Faxes are ubiquitous—and inexpensive compared to postage. Not only are
            faxes fast and easy to use, they provide immediate and reliable confirmation that a
            remote fax machine received the message. In parts of the developing world, fax is a
            lifeline—the only reliable means of exchanging important business, government, and
            personal documents.

            The fax store-and-forward solution addresses each of these issues through a
            combination of Cisco and partner technology (see in following Figure):

                      Integration of fax with electronic documents converts faxes into
                       Multipurpose Internet Mail Extension (MIME) messages with attached
                       Tagged Image File Format (TIFF) documents that can be reconverted to
                       fax or accessed electronically.
                     Improved delivery control is realized through directory services based on
                       Simple Mail Transfer Protocol (SMTP) mail servers (provided by
                       Netscape or Software.com) plus directory services that map fax numbers
                       to user accounts.
                     Message storage and retrieval includies software to convert PC documents
                     into TIFF documents.
                     Least-cost routing, billing, management and user access via the Web is
                       achieved through partner software that enables service providers to offer
                       store-and-forward fax services profitably.

            CORPORATE VOICE AND DATA :

                   Cisco GGSN enables offering alternative solutions where GGSN can be
            placed at the customer premises. Based on leading routing technology, Cisco IOS
            software, it is the ideal solution that integrates GPRS with already-deployed IP
            services, such as virtual private dial-up networks (VPDNs) and voice over IP (see in
            following Figure ).




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            VIRTUAL PRIVATE NETWORK CORPORATE SOLUTIONS :

                   High scalable SGSN nodes could be used to create a GPRS corporate solution.
            Scalability, interworking features, and standard protocols are the key aspects that
            Cisco is introducing in all its innovative and advanced projects. Distributed solutions
            with intelligent devices can give operators a competitive advantage, especially in the
            small office/home office (SOHO) business. (see in following Figure).




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            8       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. The combination
            of these characteristics provides a wide spectrum of possible applications that can be
            offered to mobile subscribers. The core network components offered by Cisco enable
            seamless access to these applications, whether they reside in the service provider's
            network or the public Internet.

                   In general, applications can be separated into two high-level categories:
            corporate and consumer. These include:

                            Communications—E-mail; fax; unified messaging; intranet/Internet
                    access
                            Value-added services (VAS)—Information services; games
                            E-commerce—Retail; ticket purchasing; banking; financial trading
                            Location-based      applications—Navigation;     traffic  conditions;
                    airline/rail schedules; location finder
                            Vertical applications—Freight delivery; fleet management; sales-force
                    automation
                            Advertising

            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. This differs from those applications in which users believe
            that they are accessing a service provided or forwarded by the network operator.

            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
            (virtual private networks [VPNs]).

            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

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            service information. More recently, companies have begun using the Internet as an
            environment for carrying out business, through e-commerce.

            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). In the
            latter case, a notification will be forwarded to their mobile terminal; the notification
            will include the first few lines of the e-mail as well as details of the sender, the
            date/time, and the subject. Fax attachments can also accompany e-mails.

            UNIFIED MESSAGING :

                   Unified messaging uses a single mailbox for all messages, including voice
            mail, faxes, e-mail, 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. Two terms that are frequently
            used with respect to the delivery of data applications are push and pull, as defined
            below.

                          Push refers to the transmission of data at a predetermined time, or
                    under predetermined conditions. It could also apply to the unsolicited supply
                    of advertising (for example, delivery of news as it occurs, or stock values
                    when they fall below a preset value).
                          Pull refers to the demanding of data in real time by the user (for
                    example, requesting stock quotes or daily news headlines).

            To be valuable to subscribers, this content must posses several characteristics:

                           Personalized information is tailored to user-specific needs with
                    relevant information. A stock ticker, focusing on key quotes and news, or an e-
                    commerce application that knows a user's profile are two examples of
                    personalized information.
                           Localized content is based on a user's current location; it can include
                    maps, hotel finders, or restaurant reviews.
                           Convenience suggests that the user interface and menu screens are
                    intuitive and easy to navigate.
                           Trust pertains primarily to e-commerce sites where the exchange of
                    financial or other personal information is required.


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            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:

                    The popularity among banks of encouraging electronic banking comes from
            the comparable costs of making transactions in person in a bank to making them
            electronically. Specific banking functions that can be accomplished over a wireless
            connection include: balance checking, moving money between accounts, bill
            payment, and overdraft alert.

            FINANCIAL TRADING :

                   The immediacy with which transactions can be made using the Internet and
            the requirement for up-to-the-minute information has made the purchasing of stocks a
            popular application. By providing push services such as those detailed in the VAS
            section earlier and coupling these with the ability to make secure transactions from
            the mobile terminal, a very valuable service unique to the mobile environment can be
            provided.

            LOCATION-BASED SERVICES AND TELEMATICS :
                    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. This technology also has vertical
            applications such as workforce management and vehicle tracking.

            VERTICAL APPLICATIONS :
                   In the mobile environment, vertical applications apply to systems utilizing
            mobile architectures to support the carrying out of specific tasks within the value
            chain of a company, as opposed to applications that are then being offered for sale to
            a consumer. Examples of vertical applications include:

                            Sales support—Provision of stock and product information for sales
                    staff, as well as integration of their use of appointment details and the remote
                    placing of orders
                            Dispatching—Communication of job details such as location and
                    scheduling; permitting interrogation of information to support the job
                            Fleet management—Control of a fleet of delivery or service staff,
                    monitoring their locations and scheduling work
                            Parcel delivery—Tracking the locations of packages for feedback to
                    customers and performance monitoring



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            ADVERTISING:

                   Advertising services will be offered as a push type information service.
            Advertising may be offered to customers to subsidize the cost of voice or other
            information services. Finally, 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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            9       LIMITATIONS OF GPRS : -
                   It should already be clear that GPRS is an important new enabling mobile data
            service which offers a major improvement in spectrum efficiency, capability and
            functionality compared with today's nonvoice mobile services. However, it is
            important to note that there are some limitations with GPRS, which can be
            summarized as:

            LIMITED CELL CAPACITY FOR ALL USERS :
                    GPRS does impact a network's existing cell capacity. There are only limited
            radio resources that can be deployed for different uses- use for one purpose precludes
            simultaneous use for another. For example, voice and GPRS calls both use the same
            network resources. The extent of the impact depends upon the number of timeslots, if
            any, that are reserved for exclusive use of GPRS. However, GPRS does dynamically
            manage channel allocation and allow a reduction in peak time signalling channel
            loading by sending short messages over GPRS channels instead.

            RESULT: NEED FOR SMS as a complementary bearer that uses a different type of
            radio resource.

            SPEEDS MUCH LOWER IN REALITY :
                    Achieving the theoretical maximum GPRS data transmission speed of 172.2
            kbps would require a single user taking over all eight timeslots without any error
            protection. Clearly, it is unlikely that a network operator will allow all timeslots to be
            used by a single GPRS user. Additionally, the initial GPRS terminals are expected be
            severely limited- supporting only one, two or three timeslots. The bandwidth available
            to a GPRS user will therefore be severely limited. As such, the theoretical maximum
            GPRS speeds should be checked against the reality of constraints in the networks and
            terminals. The reality is that mobile networks are always likely to have lower data
            transmission speeds than fixed networks.

            RESULT: Relatively high mobile data speeds may not be available to individual
            mobile users until Enhanced Data rates for GSM Evolution (EDGE) or Universal
            Mobile Telephone System (3GSM) are introduced.

            SUPPORT OF GPRS MOBILE TERMINATE BY TERMINALS IS
            NOT ENSURED:
                   At the time of writing, there has been no confirmation from any handset
            vendors that mobile terminated GPRS calls (i.e. receipt of GPRS calls on the mobile
            phone) will be supported by the initial GPRS terminals. Availability or not of GPRS
            MT is a central question with critical impact on the GPRS business case such as
            application migration from other nonvoice bearers.

                   By originating the GPRS session, users confirm their agreement to pay for the
            delivery of content from that service. This origination may well be performed using a
            Wireless Application Protocol (WAP) session using the WAP microbrowser that will

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            be built into GHPRS terminals. However, mobile terminated IP traffic might allow
            unsolicited information to reach the terminal. Internet sources originating such
            unsolicited content may not be chargeable. A possible worse case scenario would be
            that mobile users would have to pay for receiving unsolicited junk content. This is a
            potential reason for a mobile vendor NOT to support GPRS Mobile Terminate in their
            GPRS terminals.

                   However, there is always the possibility of unsolicited or unwanted
            information being communicated through any media, but that does not mean that we
            would wish to preclude the possibility of any kind of communication through that
            means altogether. A network side solution such as GGSN or charging platform
            policing would be preferable rather than a non-flexible limitation built into all the
            GPRS handsets.

                    When we asked Nokia about this issue, it commented: "Details of the Nokia
            GPRS terminals are not available at this time. It is too early to confirm whether MT
            will be supported in the first Nokia GPRS terminals". The company's policy is not to
            make details available about products before they are announced. Readers should
            contact the GSM Association, Mobile Lifestreams Limited and/ or the vendors
            directly to encourage them to incorporate support for GPRS MT in their initial
            terminals.

            RESULT: GPRS usability and therefore business case is threatened if GPRS MT is
            not supported by GPRS terminals.

            SUBOPTIMAL MODULATION :

                   GPRS is based on a modulation technique known as Gaussian minimum-shift
            keying (GMSK). EDGE is based on a new modulation scheme that allows a much
            higher bit rate across the air interface- this is called eight-phase-shift keying (8 PSK)
            modulation. Since 8 PSK will also be used for 3GSM, network operators will need to
            incorporate it at some stage to make the transition to third generation mobile phone
            systems.

            RESULT: NEED FOR EDGE.

            TRANSIT DELAYS :
                   GPRS packets are sent in all different directions to reach the same destination.
            This opens up the potential for one or some of those packets to be lost or corrupted
            during the data transmission over the radio link. The GPRS standards recognize this
            inherent feature of wireless packet technologies and incorporate data integrity and
            retransmission strategies. However, the result is that potential transit delays can occur.

                    Because of this, applications requiring broadcast quality video may well be
            implemented using High Speed Circuit Switched Data (HSCSD). HSCSD is simply a
            Circuit Switched Data call in which a single user can take over up to four separate
            channels at the same time. Because of its characteristic of end to end connection
            between sender and recipient, transmission delays are less likely.


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            RESULT: NEED FOR HSCSD.



            NO STORE AND FORWARD :
                   Whereas the Store and Forward Engine in the Short Message Service is the
            heart of the SMS Center and key feature of the SMS service, there is no storage
            mechanism incorporated into the GPRS standard, apart from the incorporation of
            interconnection links between SMS and GPRS.

            RESULT: NEED FOR SMS.




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GPRS


            10      RELATED GPRS CHALLENGES : -
            BILLING:
                    GPRS is a different kind of service from those typically available on today’s
            mobile networks. GPRS is essentially a packet switching overlay on a circuit
            switching network. The GPRS specifications stipulate the minimum charging
            information that must be collected in the Stage 1 service description. These include
            destination and source addresses, usage of radio interface, usage of external Packet
            Data Networks, usage of the packet data protocol addresses, usage of general GPRS
            resources and location of the Mobile Station. Since GPRS networks break the
            information to be communicated down into packets, at a minimum, a GPRS network
            needs to be able to count packets to charging customers for the volume of packets
            they send and receive. Today's billing systems have difficulties handling charging for
            today's nonvoice services. It is unlikely that circuit switched billing systems will be
            able to process a large number of new variables created by GPRS.

                    GPRS call records are generated in the GPRS Service Nodes. The GGSN and
            SGSN may not be able to store charging information but this charging information
            needs to be processed. The incumbent billing systems are often not able to handle real
            time Call Detail Record flows. As such, an intermediary charging platform is a good
            idea to and preparing it for submission to perform billing mediation by collecting the
            charging information from the GPRS nodes the billing system. Packet counts are
            passed to a Charging Gateway that generates Call Detail Records that are sent to the
            billing system.

                    However, the crucial challenge of being able to bill for GPRS and therefore
            earn a return on investment in GPRS is simplified by the fact that the major GPRS
            infrastructure vendors all support charging functions as part of their GPRS solutions.
            Additionally, a wide range of other existing non-GSM packet data networks such as
            X.25 and Cellular Digital Packet Data (CDPD) are in place along with associated
            billing systems.

                    It may well be the case that the cost of measuring packets is greater than their
            value. The implication is that there will NOT be a per packet charge since there may
            be too many packets to warrant counting and charging for. For example, a single
            traffic monitoring application can generate tens of thousands of packets per day. Thus
            the charging gateway function is more a policing function than a charging function
            since network operators are likely to tariff certain amounts of GPRS traffic at a flat
            rate and then need to monitor whether these allocations are far exceeded.

                   This is not to say that we will end up with the free Internet Service Provider
            model that has become established on the fixed Internet in which users pay no fixed
            monthly charge and network operators rely on advertising sales on mobile portal sites
            to make money. There is a premium for mobility and there is frankly a shortage of
            mobile bandwidth that limits the extent to which that bandwidth is viewed as a
            commodity. And given the additional customer care and billing complexity associated
            with mobile



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GPRS

                   Internet and nonvoice services, network operators would be ill advised to
            reduce their prices in such a way as to devalue the perceived value of mobility.

            TARIFFING:
                   Decisions on charging for GPRS by packet or simply a flat monthly fee are
            contentious but need to be made. Charging different packets at different rates can
            make things complicated for the user, whilst flat rates favor heavy users more than
            occasional ones.

                    We believe that the optimal GPRS pricing model will be based on two
            variables- time and packet. Network operators should levy a nominal per packet
            charge during peak times plus a flat rate, no per packet charge during non peak times.
            Time and packet related charging will encourage applications such as remote
            monitoring, meter reading and chat to use GPRS overnight when spare network
            capacity is available. Simultaneously, a nominal per packet charge during the day will
            help to allocate scarce radio resources and charge radio heavy applications such as file
            and image transfer more than applications with lower data intensity. It has the
            advantage that it will automatically adjust customer charging according to their
            application usage.

            As such the optimal charging model could well be a flat rate charge during off-peak
            times along with a per packet charge during peak times.

            CUSTOMER SERVICE :
                    Value-added network services such as mobile data, mobile Internet and
            unified messaging all generate certain specific customer problems and requirements,
            thereby requiring customer service personnel to be aware of these issues and know
            how to solve them.

                    Nonvoice services are surprisingly complex- involving unique configurations
            of phone types, data cards, handheld computers, subscriptions, operating systems,
            Internet service providers and so on. Some network operators require customers to opt
            into certain value added services rather than including them as part of the core
            subscription- necessitating a customer service process. It is even possible to write a
            350 page book about the SHORT message service (it is called "YES2SMS")!

                   In theory, the need for dedicated customer service for Circuit Switched Data,
            SMS and other nonvoice mobile services will decrease in the future as terminals and
            services become easier to use and as the services themselves are used more widely for
            customer service purposes.

                    The reality in the short and medium term is that the need for customer support
            for value-added services will increase not decrease as awareness of services and their
            usage increases, and as new services and terminals come onto the marketplace.

                   Rather than keeping everything in-house or outsourcing everything, we are a
            proponent of an approach that keeps first line support and customer contact in-house,
            whilst outsourcing the difficult specific customer service problems arising from
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GPRS

            connectivity issues and so on. In this way, the network operator is aware of and in
            control of the kinds of questions and problems its customers are asking.

                     It is well worth incurring the cost to get the customer aware, educated and
            initially set up with data services, because, for example, once the PC data card has
            been successfully connected to the laptop to the Internet software and so on, the same
            configuration can be repeatedly used. The one-off customer requirement leads to
            ongoing usage.




            11      GLOSSARY OF TERMS : -

TheDirectData.com                                                                               Page 36
GPRS

            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
            Telecommunications System [UMTS], IMT-2000; sometimes GPRS is called 3G in
            North America)
            3GPP
            3G Partnership Project
            BG
            Border gateway
            BGP
            Border Gateway Protocol
            bps
            Bits per second
            BSC
            Base Station Controller
            BTS
            Base transceiver station
            CS
            Circuit switched
            DHCP
            Dynamic Host Configuration Protocol
            DNS
            Domain Name System
            EDGE
            Enhanced data rates for GSM evolution; upgrade to GPRS systems that requires new
            base stations and claims to increase bandwidth to 384 kbps
            ETSI
            European Telecommunications Standards Institute
            Gb
            Interface between a SGSN and a BSS
            Interface between a GGSN and a HLR
            Gc
            Interface between a GGSN and a HLR

            Gd

            Interface between a SMS-GMSC and a SGSN, and between a SMS-IWMSC and a
            SGSN
            Gf
            Interface between a SGSN and an EIR
            GGSN
            Gateway GPRS Support Node
            Gi
            Reference point between GPRS and an external packet data network
            GIWU
            GSM interworking unit
            GMSC
            Gateway mobile services switching center

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GPRS

            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
            Gr
            Interface between a SGSN and a HLR
            Gs
            Interface between a SGSN and a MSC/VLR

            GSM
            Global System for Mobile Communications; most widely deployed 2G digital cellular
            mobile network standard
            GSN
            GPRS Support Node (xGSN)
            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
            IP
            Internet Protocol
            ISP
            Internet service provider
            L2TP
            Layer two Tunneling Protocol
            LLC
            Logical Link Control
            MAC
            Medium Access Control
            MM
            Mobility management
            MS
            Mobile station
            MSC
            Mobile services switching center
            NAS
            Network access server
            OA&M
            Operations, administration, and management
            OSS
            Operations Support System

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GPRS

            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; the mobile equivalent of the PSTN
            PSPDN
            Packet Switched Public Data Network
            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
            SS7
            Signaling System Number 7
            TCP
            Transmission Control Protocol
            TE
            Terminal equipment
            TDMA
            Narrowband digital TDMA standard; uses same frequencies as AMPS, thus is also
            known as D-AMPS or digital AMPS
            TS
            Time slot
            Um
            Interface between the MS and the GPRS fixed network part
            VAS
            Value-added services
            VLR

TheDirectData.com                                                                                Page 39
GPRS

            Visitor location register
            VPN
            Virtual private network
            WAP
            Wireless access Protocol; important protocol stack (Layers 4 through 7 of the OSI
            model), 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

            REFERENCES : -


                       www.nokiagprs.com
                       www.gsmword.com
                       www.cisco-gprs.com
                       www.gprs.com
                       www.hutchgprs.com
                       www.3gworld.com
                       PC Quest magazine




TheDirectData.com                                                                                 Page 40

				
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