Friday, July 26, 2013
ABSTRACT
General
Packet Radio Service (GPRS) is
a new service
designed for digital
cellular networks. It utilizes
packet radio principle
and can be
used for carrying
end user’s packet
data protocol information
from/to a GPRS
terminal to/from other
GPRS
terminals and/or external
packet data networks.
GPRS is
a new nonvoice
value added service
that allows
information to
be sent and
received across a
mobile telephone network. It
optimizes the
use of
network resources and
radio resources. Strict separation
between radio subsystem
and network
subsystem is maintained
allowing the network
subsystem to be
reused with
other radio
access technologies.
GPRS is
an enhancement to existing
GSM networks that introduces
packet data transmission,
enabling "always
on" mobility. This means
that users can
choose to be
permanently logged on to
e-mail , Internet access and
other services, but
do not have to
pay for these
services unless sending
or receiving information.
GPRS will
provide a boost
to mobile data
usage and usefulness.
INTRODUCTION
GPRS uses a
packet – mode technique to
transfer high-speed and
low-speed data and signaling
in an efficient
manner over GSM
radio networks. GPRS
allows SMS transfer
over GPRS radio
channels. GPRS is
designed to support
from intermittent and
bursty data transfers
through to occasional transmission
of large volumes
of data. Four different
quality of service levels
are supported. GPRS is
designed for fast
reservation to begin
transmission of packets,
typically 0,5 to 1 second.
Charging will typically be
based on the amount of
data transferred.
Services such as the Internet, videoconferencing and on-line shopping
will be as smooth as talking on the phone, moreover we'll be able to access
these services whether we are at work, at home or travelling.
Some of the
key features of
GPRS are:
Speed immediacy, new applications, better applications, service access, packet switching, spectrum efficiency, internet aware…
Some of
the applications are
chat, textual and visual
information, still images, moving
images, web browsing, audio,
internet e-mail, file transfer, home automation.
GPRS
SYSTEM
First, there is a notebook computer connected to a
GPRS-capable cell phone or modem, either through a serial cable or other type
of connection such as Universal Serial Bus (USB) or local wireless link, or a
PC Card. The GPRS phone or modem communicates with GSM base stations, but
unlike circuit-switched data calls, which are connected, to voice networks by
the mobile switching center, GPRS packets are sent from the base station to
what is called a Serving GPRS Support Node (SGSN). The
SGSN is the
node within the
GSM infrastructure that sends and receives data to and from the
mobile stations. It also keeps track of the mobiles within its service area.
The SGSN communicates with what is called the Gateway GPRS Support Node
(GGSN), a system that maintains connections with other networks such as
the Internet, X.25 networks or private networks.
When the mobile station sends
packets of data, it is via the SGSN to the GGSN, which converts them for
transmission over the desired network, which could be the Internet, X.25
networks or private networks. IP packets from the Internet addressed for the
mobile station are received by the GGSN, forwarded to the SGSN and then
transmitted to the mobile station.
To forward IP or X.25 packets
between each other, the SGSN and GGSN encapsulate these packets using a
specialized protocol called the GPRS tunnel protocol (GTP) which operates over
the top of standard TCP/IP protocols.
TRANSFER OF DATA
The most common methods used for
data transfer are circuit-switching and packet-switching. With circuit-switched
transmission the dedicated circuit is first established across a sequence of
links and then the whole channel is allocated to a single user for the whole
duration of the call. With packet switched transmission, the data is first cut
in to small parts called packages which are then sent in sequence to the
receiver, which again builds the packages back together. This ensures that the
same link resources can be shared at the same time by many different users. The
link is used only when the user has something to send. When there is no data to
be sent the link is free to be used by another call. Packet switching is ideal
for bursty traffic, e.g. voice.
Technology used by GPRS :The main objectives to
be reached by implementing GPRS are the following:
·
give
support for bursty traffic
·
use
efficiently network and radio resources
·
provide
flexible services at relatively low costs
·
possibility
for connectivity to the Internet
·
provide
fast access time
·
to
have and support flexible co-existence with GSM voice
Importance of packet data
technology: Because
packet provides a seamless and immediate connection from a mobile PC to the
Internet or corporate intranet allowing all existing Internet applications such
as e-mail and Web browsing to operate smoothly without even needing to dial
into an Internet service provider. Multiple users can share the same radio
channel very efficiently. In contrast, with current circuit-switched
connections, users have dedicated connections during their entire call, whether
or not they are sending data.With packet data, users will only pay for the
amount of data they actually communicate, and not the idle time. In fact, with
GPRS, users could be "virtually" connected for hours at a time and
only incur modest connect charges.X.25 defines a set of communications
protocols that prior to the Internet constituted the basis of the world’s
largest packet data networks. Any existing IP or X.25 application will now be
able to operate over a GSM cellular connection.
FEATURES OF GPRS
The most important aspects of GPRS
are that it allows data transmission speeds to over 100 Kbps, that it is packet
based, and that it supports the world's leading Internet communications
protocols, Internet Protocol (IP) and X. 25.
The fact that GPRS will operate at much
higher speeds than current networks should provide a huge advantage from a
software perspective. Today, wireless middleware is often required to allow
slow speed mobile clients to work with fast networks for applications such as
e-mail, databases, groupware or Internet access. With GPRS, wireless middleware
will often be unnecessary, and thus it should be easier to deploy wireless
solutions than ever before.
Whereas today’s wireless
applications tend to be text oriented, the high throughput offered by GPRS will
finally make multimedia content, including graphics, voice and video practical.
KEY USER
FEATURES :
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, 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
·
a subscription
to a mobile
telephone network that
supports GPRS
·
use of
GPRS must be
enabled for that
user. Automatic access to the GPRS
may be allowed
by some mobile
network operators
·
knowledge of
how to send
and/ or receive GPRS
information using their
specific model of
mobile phone, including
software and hardware
configuration
·
a destination
to send or
receive information through
GPRS.
KEY NETWORK FEATURES:
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. 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
up grade 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. The Internet is
an 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.
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 ) .
Internet aware :
Internet aware :
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. 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. Web browsing is
a very important
application for GPRS.
Supports TDMA and GSM :
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.
APPLICATIONS
FOR GPRS
ü Chat
ü Textual and Visual
Information
ü Still Images
ü Moving Images
ü Web Browsing
ü Document Sharing /
Collaborative Working
ü Audio
ü Job Dispatch
ü Corporate Email
ü Internet Email
ü Vehicle Positioning
ü Remote LAN Access
ü File Transfer
ü Home Automation
LIMITATIONS OF GPRS
ü Limited Cell Capacity
For All Users :-
There are
only limited radio
resources that can
be deployed for
different uses – use for
one purpose precludes
simultaneous use for
another.
ü Speeds Much Lower
in Reality:-
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.
ü Support of GPRS Mobile Terminate by Terminals is not Ensured :-
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
micro browser that
will be built
into GHPRS terminals.
ü
Sub optimal
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.
ü 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.
ü No Store and
Forward
: -
There is
no storage mechanism
incorporated into the
GPRS standard, apart
from the incorporation
of interconnection links
between SMS and
GPRS.
CONCLUSION
The global GPRS
(General Packet Radio Service) market is now beginning to take off. The
introduction of GPRS is one of the key steps in the evolution of today’s GSM
networks to 3G (Third Generation), and GSM operators around the world are
upgrading their networks.
GPRS allows
innovative services to be created enabling new and previously inaccessible
market segments to be addressed, increasing customer loyalty and reducing
churn. Successful services offer value to consumers and business users by
exploiting the specific capabilities of the wireless networks and complementary
terminologies. These are seen as personalized, quick response, localized to the
user. GPRS packet-based service costs users less than
circuit-switched services since communication channels are being used on a
shared-use, as-packets-are-needed basis rather than dedicated only to one user
at a time irrespective of usage.
Benefits:
Ø Faster data speeds and "always
on" mobility.
Ø Almost instantaneous connection set-up.
Ø Connection to an abundance of data
sources around the world, through support for multiple protocols, including IP.
Ø A step towards full 3G services.
