31-05-2012, 03:56 PM
GPRS and 3G Wireless Systems
[attachment=23727]
Introduction
The wireless technology has come a long way since its inception. Last decade has seen an impressive
growth in the number of wireless users all over the world. The use of wireless technology is now
not just limited to wireless telephony but there is now a huge demand of wireless technology for
many types of applications like Internet and web browsing, video and other text and multimedia
based application. In this report we give an overview of the rst and second generation wireless
technologies and then we nally discuss the GPRS and 3G Wireless Networks in details.
General Cellular Concepts
In a cellular system the hand-sets carried by the users are called Mobile Stations (MS). The Mobile
Stations communicate to the Base Stations (BS) through a pair of frequency channels, one for
up-link and another for down-link. All the base stations of a Cellular systems are controlled by
a central switching station called Mobile Switching Center (MSC) or Mobile Telephone Switching
Oce (MTSO). The MSC is responsible for all kinds of network management functions such as
channel allocations, Hando s, billing, power control etc. The MSC is also connected to the Public
Subscriber Telephone Network (PSTN) or Public Land Mobile Network (PLMN) so as to allow the
MS to talk to a Land Line telephone or vice versa.
Generations of Wireless Systems
First Generation
The First Generation cellular systems in general used the FDMA technique and functioned more
or less exactly as described above. These systems used analog modulation techniques like FM.
The examples of rst generation cellular systems are AMPS(Advance Mobile Telephone System),
NMT (Nordic Mobile Telephone) system etc. These systems su ered from limitations like low
service quality,long call setup time,inecient use of bandwidth, susceptible to interference, bulky
and expensive equipments, support only for speech,insecure transmission etc.
Second Generation
The Second Generation cellular systems employ the digital modulation techniques and advance call
processing methods. Some of these systems use combination of TDMA and FDMA technique to
increase the number of channels. One such example is GSM (Global System for Mobile) which has
gained wide popularity and is used in most of the European countries. Some of the other systems
like IS-95 (used in USA) also use CDMA technique.
Third Generation
The Third Generation Systems will provide both speech and data at the very high speed. Though
the second generation system provide with data transmission, the data rate o ered is quite low
and is unsuitable for today's needs. The third generation systems promise to integrate all kind of
services like speech, data, audio, video, facsimile etc. through the mobile handsets. These systems
will provide much better service quality than the second generation systems and will provide much
smaller call set up delay. They will be suitable both for bursty and streamed data and will give
much better utilization of channels. The users will be billed based on the utilization of channel
rather than the time of call. This is very important for today's service demands like Internet and
mail services. Therefore the goal of the third generation cellular systems is to provide better service
quality at low cost, smaller call set up time, user friendly billing and access to a wide variety of
services through wireless.
Organization of Report
The report will discuss various features of Mobile Cellular Systems beyond second generation. In
the chapters ahead we will brie
y discuss the architecture of GSM system in order to understand
the current system implementations since the newer systems are greatly in
uenced by its design.
Finally we discuss the architecture of GPRS (also termed as 2.5G) and 3G systems in greater detail
in the coming chapters.
[attachment=23727]
Introduction
The wireless technology has come a long way since its inception. Last decade has seen an impressive
growth in the number of wireless users all over the world. The use of wireless technology is now
not just limited to wireless telephony but there is now a huge demand of wireless technology for
many types of applications like Internet and web browsing, video and other text and multimedia
based application. In this report we give an overview of the rst and second generation wireless
technologies and then we nally discuss the GPRS and 3G Wireless Networks in details.
General Cellular Concepts
In a cellular system the hand-sets carried by the users are called Mobile Stations (MS). The Mobile
Stations communicate to the Base Stations (BS) through a pair of frequency channels, one for
up-link and another for down-link. All the base stations of a Cellular systems are controlled by
a central switching station called Mobile Switching Center (MSC) or Mobile Telephone Switching
Oce (MTSO). The MSC is responsible for all kinds of network management functions such as
channel allocations, Hando s, billing, power control etc. The MSC is also connected to the Public
Subscriber Telephone Network (PSTN) or Public Land Mobile Network (PLMN) so as to allow the
MS to talk to a Land Line telephone or vice versa.
Generations of Wireless Systems
First Generation
The First Generation cellular systems in general used the FDMA technique and functioned more
or less exactly as described above. These systems used analog modulation techniques like FM.
The examples of rst generation cellular systems are AMPS(Advance Mobile Telephone System),
NMT (Nordic Mobile Telephone) system etc. These systems su ered from limitations like low
service quality,long call setup time,inecient use of bandwidth, susceptible to interference, bulky
and expensive equipments, support only for speech,insecure transmission etc.
Second Generation
The Second Generation cellular systems employ the digital modulation techniques and advance call
processing methods. Some of these systems use combination of TDMA and FDMA technique to
increase the number of channels. One such example is GSM (Global System for Mobile) which has
gained wide popularity and is used in most of the European countries. Some of the other systems
like IS-95 (used in USA) also use CDMA technique.
Third Generation
The Third Generation Systems will provide both speech and data at the very high speed. Though
the second generation system provide with data transmission, the data rate o ered is quite low
and is unsuitable for today's needs. The third generation systems promise to integrate all kind of
services like speech, data, audio, video, facsimile etc. through the mobile handsets. These systems
will provide much better service quality than the second generation systems and will provide much
smaller call set up delay. They will be suitable both for bursty and streamed data and will give
much better utilization of channels. The users will be billed based on the utilization of channel
rather than the time of call. This is very important for today's service demands like Internet and
mail services. Therefore the goal of the third generation cellular systems is to provide better service
quality at low cost, smaller call set up time, user friendly billing and access to a wide variety of
services through wireless.
Organization of Report
The report will discuss various features of Mobile Cellular Systems beyond second generation. In
the chapters ahead we will brie
y discuss the architecture of GSM system in order to understand
the current system implementations since the newer systems are greatly in
uenced by its design.
Finally we discuss the architecture of GPRS (also termed as 2.5G) and 3G systems in greater detail
in the coming chapters.