The cellular concept solves the problem of high power transmitter (large cell) by replacing it with many low power transmitters (small cells). Each cell provides coverage to only a small area. Frequency Reuse is the key feature of cellular system. SDMA (space division multiple access) is used to enable frequency reuse. Each cell has a low power transmitter called Base Station (BS) which transmits the data within a certain coverage area delimited by the circles which forms the cell. A group of cells forms a cluster, usually hexagonal in shape. Home Location Register stores the location area identity code to track the location of mobile device in its own cell, whereas the Visitor Location Register monitors the locations in roaming area. BS continually monitors signal strength of all Mobile Stations (MS) in its area. Mobile Switching Centre selects the new BS as soon as the signal strength in the current BS falls below a specified level.