Frequency Reuse

Frequency Reuse
The base station antennas are designed to achieve the desired coverage within the particular
cell. By limiting the coverage area to within the boundaries of a cell, the same group of channels
may be used to cover different cells that are separated from one another by distances large
enough to keep interference levels within tolerable limits. The design process of selecting and
allocating channel groups for all the cellular base stations within a system is called frequency
reuse or frequency planning.
In Fig. 1.1 the cells labeled with the same letter use the same group of channels. The frequency
reuse plan is overlaid upon a map to indicate where different frequency channels are used. The
hexagonal cell shape shown is conceptual and is a simplistic model of the coverage for each
base station. The hexagon has been universally adopted since the hexagon permits easy and
manageable analysis of a cellular system. Also considering geometric shapes which cover an
entire region without overlap and with equal area, hexagon has the largest area considering the
distance between the center of a polygon and its farthest perimeter points. The actual footprint
is determined by the contour in which a given transmitter serves the mobiles successfully.
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