21-01-2013, 12:03 PM
Lecture Notes on Mobile Communication
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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.
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.
How a Mobile Call is Actually Made?
In order to know how a mobile call is made, we should rst look into the basics of
cellular concept and main operational channels involved in making a call. These are
given below.
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.
Each cell has a low power transmitter with a coverage area equal to the area of the cell. This technique of substituting a single high powered transmitter by several low
powered transmitters to support many users is the backbone of the cellular concept.
[attachment=47839]
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.
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.
How a Mobile Call is Actually Made?
In order to know how a mobile call is made, we should rst look into the basics of
cellular concept and main operational channels involved in making a call. These are
given below.
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.
Each cell has a low power transmitter with a coverage area equal to the area of the cell. This technique of substituting a single high powered transmitter by several low
powered transmitters to support many users is the backbone of the cellular concept.