26-05-2012, 11:21 AM
Evolution to 3G Mobile Communication
[attachment=23109]
Introduction
The immense growth of information exchange by electronic
means has caused an unprecedented boost in the development of
telecommunications technologies, systems, and services. Communications
that were formerly carried on wires are now supplied
over radio (wireless). Thus, wireless communication, that
uncouples the telephone from its wires to the local telephone
exchange, has seen explosive growth. The Internet and the
developments in the mobile domain have fueled the first stage of
what appears to be a paradigm shift of societal dimensions. The
Internet as well as corporate intranets are becoming increasingly
wireless.
First Generation (1G) Systems
In a cellular network, there are radio ports with antennas connected
to base stations (BSs) serving the user equipment, the
mobile stations (MSs). The communication from the MS to the
BS is the uplink, and from the BS to the MS the downlink. The
downlink is contentionless, but the uplink is accessed by several
MSs; therefore, another important characteristic is the multiple
access technique used for its uplink. Frequency division multiple
access (FDMA), Time Division Multiple Access (TDMA)
[4] and Code Division Multiple Access (CDMA) [5,6] are the
most widely used physical-layer multiple access techniques.
Second Generation (2G) Systems
The development of the digital technology, on one hand, and
frequent cases when analog systems reached their full capacity,
especially in big cities, on the other hand, led to the development
of the second-generation (2G) systems. The main aim in
the design of the 2G systems was the maximization of the system
capacity measured as the number of users per spectrum per unit
area. In addition to system capacity digital 2G networks have
provided improvements to system security, performance and
voice quality. 2G makes heavy use of digital technology through
the use of digital vocoders, Forward Error Correction (FEC),
and high level digital modulation to improve voice quality,
security and call reliability.
Global System for Mobile Technology (GSM-2G)
The dominant wireless-networking technology during the past
few years has been ‘second generation’ technology, which is
digital, circuit based, and narrow band but suitable for voice and
limited data communications. The GSM technology has been a
very stable, widely accepted and most popular standard for
mobile communication. This was the first digital wireless technology
and has tried to inherently support other technologies at
its branches. In 2001, it enjoyed a 60% market share. In addition
to voice, GSM supports low rates for data services (up to 9.6
Kbps) and Short Message Services (SMS). The GSM standard
recommends the application of Gaussian Minimum Shift Keying
(GMSK) modulation.
CdmaOne, IS-95 (2G)
CdmaOne, also known as IS-95 system is the branding name for
the first generation of CDMA. Originally designed for voice,
changes specified in IS-95A now allow packet data rates up to
14.4 Kbps. The major difference between CDMA and other 2G
technologies is the modulation scheme. CDMA uses a spread
spectrum technology that distributes a signal across a wide
frequency (1.25 MHz) channel.
[attachment=23109]
Introduction
The immense growth of information exchange by electronic
means has caused an unprecedented boost in the development of
telecommunications technologies, systems, and services. Communications
that were formerly carried on wires are now supplied
over radio (wireless). Thus, wireless communication, that
uncouples the telephone from its wires to the local telephone
exchange, has seen explosive growth. The Internet and the
developments in the mobile domain have fueled the first stage of
what appears to be a paradigm shift of societal dimensions. The
Internet as well as corporate intranets are becoming increasingly
wireless.
First Generation (1G) Systems
In a cellular network, there are radio ports with antennas connected
to base stations (BSs) serving the user equipment, the
mobile stations (MSs). The communication from the MS to the
BS is the uplink, and from the BS to the MS the downlink. The
downlink is contentionless, but the uplink is accessed by several
MSs; therefore, another important characteristic is the multiple
access technique used for its uplink. Frequency division multiple
access (FDMA), Time Division Multiple Access (TDMA)
[4] and Code Division Multiple Access (CDMA) [5,6] are the
most widely used physical-layer multiple access techniques.
Second Generation (2G) Systems
The development of the digital technology, on one hand, and
frequent cases when analog systems reached their full capacity,
especially in big cities, on the other hand, led to the development
of the second-generation (2G) systems. The main aim in
the design of the 2G systems was the maximization of the system
capacity measured as the number of users per spectrum per unit
area. In addition to system capacity digital 2G networks have
provided improvements to system security, performance and
voice quality. 2G makes heavy use of digital technology through
the use of digital vocoders, Forward Error Correction (FEC),
and high level digital modulation to improve voice quality,
security and call reliability.
Global System for Mobile Technology (GSM-2G)
The dominant wireless-networking technology during the past
few years has been ‘second generation’ technology, which is
digital, circuit based, and narrow band but suitable for voice and
limited data communications. The GSM technology has been a
very stable, widely accepted and most popular standard for
mobile communication. This was the first digital wireless technology
and has tried to inherently support other technologies at
its branches. In 2001, it enjoyed a 60% market share. In addition
to voice, GSM supports low rates for data services (up to 9.6
Kbps) and Short Message Services (SMS). The GSM standard
recommends the application of Gaussian Minimum Shift Keying
(GMSK) modulation.
CdmaOne, IS-95 (2G)
CdmaOne, also known as IS-95 system is the branding name for
the first generation of CDMA. Originally designed for voice,
changes specified in IS-95A now allow packet data rates up to
14.4 Kbps. The major difference between CDMA and other 2G
technologies is the modulation scheme. CDMA uses a spread
spectrum technology that distributes a signal across a wide
frequency (1.25 MHz) channel.