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Radio Coverage
The coverage (or the transmitting power) of the base station is adjusted to the
amount of traffic, so less power is used in cities and other areas where the traffic is
heavy. The covered area in these cases may be limited to about two kilometers.
More power is permissible in less populated areas. The range in these areas may
amount to about 40 kilometres.
Figure 3: Service Areas with Radio Zones and Base Stations
A method known as the small-cell technique may be applied in areas with an
extreme demand on radio capacity. With this technique the service area to be cov-
ered is divided into a number of radio zones (see fig. 3). Each radio zone is covered
by a base station, which includes a transmitter (Tx) and a receiver (Rx). For such a
system to operate, without the base stations interfering with each other, the available
frequency band is split up, for example into six different groups (A-F), with a cer-
tain number of frequencies in each group. Allocating these groups in such a way
that no radio zone operating on a particular group of frequencies adjoins another
operating on the same frequencies makes it possible to cover an entire service area,
without any interference between the base stations. Fig. 4 shows an example of
channel allocation.
C
E
7
8
A
3
D
F
BE
D
CF
1
6
2
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C
4
B
E
5
10
F
B
Figure 4: Channel Allocation
System Introduction
A
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