24-08-2012, 04:06 PM
Lecture Notes on Mobile Communication
[attachment=32655]
Introduction
Communication is one of the integral parts of science that has always been a focus
point for exchanging information among parties at locations physically apart. After
its discovery, telephones have replaced the telegrams and letters. Similarly, the term
`mobile' has completely revolutionized the communication by opening up innovative
applications that are limited to one's imagination. Today, mobile communication
has become the backbone of the society. All the mobile system technologies have
improved the way of living. Its main plus point is that it has privileged a common
mass of society. In this chapter, the evolution as well as the fundamental techniques
of the mobile communication is discussed.
Evolution of Mobile Radio Communications
The rst wireline telephone system was introduced in the year 1877. Mobile communication
systems as early as 1934 were based on Amplitude Modulation (AM)
schemes and only certain public organizations maintained such systems. With the
demand for newer and better mobile radio communication systems during the World
War II and the development of Frequency Modulation (FM) technique by Edwin
Armstrong, the mobile radio communication systems began to witness many new
changes. Mobile telephone was introduced in the year 1946.
Present Day Mobile Communication
Since the time of wireless telegraphy, radio communication has been used extensively.
Our society has been looking for acquiring mobility in communication since then.
Initially the mobile communication was limited between one pair of users on single
channel pair. The range of mobility was de ned by the transmitter power, type of
antenna used and the frequency of operation. With the increase in the number of
users, accommodating them within the limited available frequency spectrum became
a major problem. To resolve this problem, the concept of cellular communication
was evolved. The present day cellular communication uses a basic unit called cell.
Each cell consists of small hexagonal area with a base station located at the center
of the cell which communicates with the user. To accommodate multiple users
Time Division multiple Access (TDMA), Code Division Multiple Access (CDMA),
Frequency Division Multiple Access (FDMA) and their hybrids are used. Numerous
mobile radio standards have been deployed at various places such as AMPS.
Fundamental Techniques
By de nition, mobile radio terminal means any radio terminal that could be moved
during its operation. Depending on the radio channel, there can be three di erent
types of mobile communication. In general, however, a Mobile Station (MS)
or subscriber unit communicates to a xed Base Station (BS) which in turn communicates
to the desired user at the other end. The MS consists of transceiver,
control circuitry, duplexer and an antenna while the BS consists of transceiver and
channel multiplexer along with antennas mounted on the tower. The BS are also
linked to a power source for the transmission of the radio signals for communication
and are connected to a xed backbone network.
Cellular Concept
Cellular telephone systems must accommodate a large number of users over a large
geographic area with limited frequency spectrum, i.e., with limited number of channels.
If a single transmitter/ receiver is used with only a single base station, then
sucient amount of power may not be present at a huge distance from the BS.
For a large geographic coverage area, a high powered transmitter therefore has to
be used. But a high power radio transmitter causes harm to environment. Mobile
communication thus calls for replacing the high power transmitters by low power
transmitters by dividing the coverage area into small segments, called cells. Each
cell uses a certain number of the available channels and a group of adjacent cells
together use all the available channels. Such a group is called a cluster. This cluster
can repeat itself and hence the same set of channels can be used again and again.
3G: Third Generation Networks
3G is the third generation of mobile phone standards and technology, superseding
2.5G. It is based on the International Telecommunication Union (ITU) family
of standards under the International Mobile Telecommunications-2000 (IMT-2000).
ITU launched IMT-2000 program, which, together with the main industry and standardization
bodies worldwide, targets to implement a global frequency band that
would support a single, ubiquitous wireless communication standard for all countries,
to provide the framework for the de nition of the 3G mobile systems.Several
radio access technologies have been accepted by ITU as part of the IMT-2000 framework.
3G networks enable network operators to o er users a wider range of more advanced
services while achieving greater network capacity through improved spectral
eciency. Services include wide-area wireless voice telephony, video calls, and broadband
wireless data, all in a mobile environment. Additional features also include
HSPA data transmission capabilities able to deliver speeds up to 14.4Mbit/s on the
down link and 5.8Mbit/s on the uplink.
[attachment=32655]
Introduction
Communication is one of the integral parts of science that has always been a focus
point for exchanging information among parties at locations physically apart. After
its discovery, telephones have replaced the telegrams and letters. Similarly, the term
`mobile' has completely revolutionized the communication by opening up innovative
applications that are limited to one's imagination. Today, mobile communication
has become the backbone of the society. All the mobile system technologies have
improved the way of living. Its main plus point is that it has privileged a common
mass of society. In this chapter, the evolution as well as the fundamental techniques
of the mobile communication is discussed.
Evolution of Mobile Radio Communications
The rst wireline telephone system was introduced in the year 1877. Mobile communication
systems as early as 1934 were based on Amplitude Modulation (AM)
schemes and only certain public organizations maintained such systems. With the
demand for newer and better mobile radio communication systems during the World
War II and the development of Frequency Modulation (FM) technique by Edwin
Armstrong, the mobile radio communication systems began to witness many new
changes. Mobile telephone was introduced in the year 1946.
Present Day Mobile Communication
Since the time of wireless telegraphy, radio communication has been used extensively.
Our society has been looking for acquiring mobility in communication since then.
Initially the mobile communication was limited between one pair of users on single
channel pair. The range of mobility was de ned by the transmitter power, type of
antenna used and the frequency of operation. With the increase in the number of
users, accommodating them within the limited available frequency spectrum became
a major problem. To resolve this problem, the concept of cellular communication
was evolved. The present day cellular communication uses a basic unit called cell.
Each cell consists of small hexagonal area with a base station located at the center
of the cell which communicates with the user. To accommodate multiple users
Time Division multiple Access (TDMA), Code Division Multiple Access (CDMA),
Frequency Division Multiple Access (FDMA) and their hybrids are used. Numerous
mobile radio standards have been deployed at various places such as AMPS.
Fundamental Techniques
By de nition, mobile radio terminal means any radio terminal that could be moved
during its operation. Depending on the radio channel, there can be three di erent
types of mobile communication. In general, however, a Mobile Station (MS)
or subscriber unit communicates to a xed Base Station (BS) which in turn communicates
to the desired user at the other end. The MS consists of transceiver,
control circuitry, duplexer and an antenna while the BS consists of transceiver and
channel multiplexer along with antennas mounted on the tower. The BS are also
linked to a power source for the transmission of the radio signals for communication
and are connected to a xed backbone network.
Cellular Concept
Cellular telephone systems must accommodate a large number of users over a large
geographic area with limited frequency spectrum, i.e., with limited number of channels.
If a single transmitter/ receiver is used with only a single base station, then
sucient amount of power may not be present at a huge distance from the BS.
For a large geographic coverage area, a high powered transmitter therefore has to
be used. But a high power radio transmitter causes harm to environment. Mobile
communication thus calls for replacing the high power transmitters by low power
transmitters by dividing the coverage area into small segments, called cells. Each
cell uses a certain number of the available channels and a group of adjacent cells
together use all the available channels. Such a group is called a cluster. This cluster
can repeat itself and hence the same set of channels can be used again and again.
3G: Third Generation Networks
3G is the third generation of mobile phone standards and technology, superseding
2.5G. It is based on the International Telecommunication Union (ITU) family
of standards under the International Mobile Telecommunications-2000 (IMT-2000).
ITU launched IMT-2000 program, which, together with the main industry and standardization
bodies worldwide, targets to implement a global frequency band that
would support a single, ubiquitous wireless communication standard for all countries,
to provide the framework for the de nition of the 3G mobile systems.Several
radio access technologies have been accepted by ITU as part of the IMT-2000 framework.
3G networks enable network operators to o er users a wider range of more advanced
services while achieving greater network capacity through improved spectral
eciency. Services include wide-area wireless voice telephony, video calls, and broadband
wireless data, all in a mobile environment. Additional features also include
HSPA data transmission capabilities able to deliver speeds up to 14.4Mbit/s on the
down link and 5.8Mbit/s on the uplink.