Mobile Telecommunication Networks
Principle of sectorization

In the previous chapter you have learned that each cell of any mobile network is operated by one particular base station. However, for large area covered by mobile networks, this concept is not appropriate, especially in terms of a high number of base stations. Nevertheless, this number can be significantly reduced by using the principle of sectorization.

Let us now divide a single cluster in the previous figure into 21 smaller cells (see figure below - section a)). The number of available channels is not so changed, but there is increased number of base stations to 21. However, we can significantly reduce the number of base stations by principle of sectorization to 7. This could be accomplished under condition that the individual base stations are not placed in the centres of cells, but in the intersection points of three adjacent cells forming one sector (see figure below - section b)).

Principle of sectorization of cellular network

Three separated directional antennas with three transmitters and receivers will be used for each of these seven stations. The number of base stations in this case is the same as in the previous figure (section b)) with the distribution of the service area into cells, but configuration of a network is much more efficient due to operating characteristics (for example lower transmission power and increasing the number of mobile stations which can be simultaneously served).

Small cells (with range of approximately 10 up to 500 m) will be necessary to use in the areas with high density of users. In areas with lower density it is sufficient to deploy cells with larger radius (with range approximately 1 up to 10 km) and for very lightly loaded areas can be the cell diameter even few kilometres.