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Wire and Wireless Communication Applications Chap. 8
MSC
CO
Figure 8–29
Cellular telephone system.
station. This base station is connected via telephone lines or a microwave link to the mobile
switching center (MSC). The MSC connects the user to the called party. If the called party is
land based, the connection is via the central office (CO) to the terrestrial telephone network.
If the called party is mobile, the connection is made to the cellular site that covers the area in
which the called party is located, using an available radio channel in the cell associated with
the called party. Theoretically, this cellular concept allows any number of mobile users to be
accommodated for a given set of radio channels. That is, if more channels are needed, the
existing cell sizes are decreased, and additional small cells are inserted, so that the existing
channels can be reused more efficiently. The critical consideration is to design the cells for
acceptable levels of cochannel interference [Lee, 1986]. As the mobile user travels from one
cell to another, the MSC automatically switches the user to an available channel in the new
cell, and the telephone conversation continues uninterrupted.
The cellular concept has the following advantages:
• Large subscriber capacity.
• Efficient use of the radio spectrum.
• Service to hand-held portables, as well as vehicles.
• High-quality telephone and data service to the mobile user at relatively low cost.
Cellular phone use has grown by leaps and bounds since it was introduced in the United
States in 1983. Today, we have smartphones with computing capacity that not only allow telephone
calls but allow us to take pictures and run applications such as maps, calendars, e-mail,
and Web browsing. This has been popularized by the Palm phone, the Blackberry, the iPhone,
and others. It has been reported that as many as 22% of cell phone users have smartphones