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
2.1.3 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
5.5.2 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
8.1.1 Intranet Access
8.1.2 Internet Access
8.1.3 E-Mail and Fax
8.1.4 Unified Messaging
8.2 Value-Added Services
8.2.3 Financial Trading
8.3 Location-Based Services and Telematics
8.4 Vertical Applications
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
10.3 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.
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
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
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Throughout 1999 – 2000 Network operators place trial and
commercial contracts for GPRS
Incorporation of GPRS infrastructure into
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
2002 Typical single user throughput is likely to
be 112 kbps.
GPRS Phase 2/ EDGE begins to emerge
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.
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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
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
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
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
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
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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
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
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
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
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
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
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
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
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
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
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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
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
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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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
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
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
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
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
GGSN OVERVIEW :
GGSN combines in one box:
GGSN features as defined by the European Telecommunication Standards
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
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
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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
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
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
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
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
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 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.
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
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 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
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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
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
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
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
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
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
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
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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10 RELATED GPRS CHALLENGES : -
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
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
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
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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.
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
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
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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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
11 GLOSSARY OF TERMS : -
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Second generation; generic name for second generation of digital mobile networks
(such as GSM, and so on)
Third generation; generic name for next-generation mobile networks (Universal
Telecommunications System [UMTS], IMT-2000; sometimes GPRS is called 3G in
3G Partnership Project
Border Gateway Protocol
Bits per second
Base Station Controller
Base transceiver station
Dynamic Host Configuration Protocol
Domain Name System
Enhanced data rates for GSM evolution; upgrade to GPRS systems that requires new
base stations and claims to increase bandwidth to 384 kbps
European Telecommunications Standards Institute
Interface between a SGSN and a BSS
Interface between a GGSN and a HLR
Interface between a GGSN and a HLR
Interface between a SMS-GMSC and a SGSN, and between a SMS-IWMSC and a
Interface between a SGSN and an EIR
Gateway GPRS Support Node
Reference point between GPRS and an external packet data network
GSM interworking unit
Gateway mobile services switching center
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Interface between two GSNs within the same PLMN
Interface between two GSNs in different PLMNs
General Packet Radio Service; upgrade to existing 2G digital mobile networks to
provide higher-speed data services
Interface between a SGSN and a HLR
Interface between a SGSN and a MSC/VLR
Global System for Mobile Communications; most widely deployed 2G digital cellular
mobile network standard
GPRS Support Node (xGSN)
GPRS Tunneling Protocol
High-Level Data Link Control
Home location register
High-speed circuit-switched data; software upgrade for cellular networks that gives
each subscriber 56K data
Internet service provider
Layer two Tunneling Protocol
Logical Link Control
Medium Access Control
Mobile services switching center
Network access server
Operations, administration, and management
Operations Support System
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Packet control unit
Personal digital assistant
Packet data network
Packet Data Protocol
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
Packet Switched Public Data Network
Public Switched Telephone Network
Permanent virtual circuit
Quality of service
Remote Authentication Dial-In User Service
Radio Link Protocol
Serving GPRS Support Node
Short message service
Short message service center
Signaling System Number 7
Transmission Control Protocol
Narrowband digital TDMA standard; uses same frequencies as AMPS, thus is also
known as D-AMPS or digital AMPS
Interface between the MS and the GPRS fixed network part
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Visitor location register
Virtual private network
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 : -
PC Quest magazine
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