Module
5
Broadcast Communication
Networks
Version 2 CSE IIT , Kharagpur
Lesson
9
Cellular Telephone
Networks
Version 2 CSE IIT , Kharagpur
Specific Instructional Objectives
At the end of this lesson, the student will be able to:
• Explain the operation of Cellular Telephone networks
• Explain the operation of the first generation cellular network - AMPS
• Distinguish between first generation and second-generation cellular networks
• Explain the operation of the second-generation cellular networks
• State the goals of 3G cellular networks
5.9.1 Introduction
In the early years of mobile radio systems, a large coverage was achieved by using a
single high-powered transmitter with the antenna mounted on tall tower. Although a large
coverage could be attained by this approach, it does not allow the reuse of the same radio
frequencies due to interference. The cellular concept was invented in solving the spectral
congestion and user capacity. Cellular telephony is a system-level concept, which
replaces a single high power transmitter with a large number of low-power transmitters
for communication between any two devices over a large geographic area. Primary goal
of the cellular telephone network is to provide wireless communication between two
moving devices, called mobile stations or between one mobile unit and a stationary unit,
commonly referred to as land-line unit. To accommodate a large number of users over a
large geographic area, the cellular telephone system uses a large number of low-power
wireless transmitters to create cells. Variable power levels allow cells to be sized
according to subscriber density and demand within a particular region. As mobile users
travel from cell to cell, their conversations are handed off between cells. Channels
(frequencies) used in one cell can be reused in another cell some distance away, which
allows communication by a large number stations using a limited number of radio
frequencies. To summarize,