Page 60 - Basics of Electrical, Electronic and Communication

332 Chapter 17. Advanced communication Systems

Cell 2

Cell 7 Cell 3

Cell 1
Cell 6 Cell 4

Cell 2 Cell 5

Cell 7 Cell 3 Cell 2

Cell 1 Cell 7 Cell 3
Cell 6 Cell 4
Cell 1
Cell 5 Cell 6 Cell 4

Cell 5

Figure 17.13: Illustration of frequency reuse concept. Cells with the same
name use the same set of frequencies. A small cluster is outlined in bold and
replicated over the coverage area. In this example, cluster size N = 7 and
frequency reuse factor is 1/7 since each cell contains one-seventh of the total
number of available channels.

Consider a cellular system which has a total of S duplex chan-
1
nels available for use. If each cell is allocated a group of K channels
(K < S) and if S channels are divided among N cells into unique
and disjoint channel groups with each have the same number of chan-
nels, the total number of available radio channels can be expressed as
S = KN. The N cells which collectively use the complete set of
available frequencies is called a cluster.
The cells can be grouped in clusters of 7, 12 and 19 etc. to form a
repetitive pattern. If a cluster is replicated M times within the system,
the total number of duplex channels C, can be used as measure of

1
Two way communication by using the same channel

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