Present Day Mobile Communication

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, PACS,

GSM, NTT, PHS and IS-95, each utilizing dierent set of frequencies and allocating
dierent number of users and channels.