As the demand for wireless service increases, the number of channel assigned to a cell becomes insufficient to support required number of at this point cellular design techniques are needed to provide more channel per unit coverage area.


•There are three techniques for improving sir capacity in cellular system:

1) Cell splitting :-

-Cell splitting is the process of sub-dividing a congested cell into smaller cell, each with its own base station and a corresponding reduction in antenna height and transmitter power.

-Cell splitting increases the capacity of cellular systemsince it increasing number of times that channels are reduced preserves frequency reuse plan.

-define new cells which have smaller radius that original cells and by installing the smallest cell is called microcells between existing cells, that is radius will be half of the original cell. Does capacity increases due to additional number of channels per unit area.

-pr(at the old cell boundary) is proportional to pt1(R)^-n

-pr(at the new cell boundary) is proportional to pt2(R/2)^-n

-Take n= 4, we get

Pt2= pt1/ 16



2) Sectoring :-

-This is another method to increase cellular capacity and coverage by keeping cell radius unchanged and decreasing D/R ratio.

- In sectoringcapacity improvement is achieved by reducing the number of cells in a cluster and thus increasing the frequency reuse.

-the factor by which the CO channel interference is reduced depends on the amount of sectoring used.

a) 120° sectoring

b) 60° sectoring



3) Coverage zone/Microcells zone :-

-This approach was presented by leeto solve the problem of an increased load on the switching and control link elements of the mobile system due to sectoring.

-it is based on a microcell concept for 7 re-use. In this scheme, each of the three zones sites are connected to a single base station and share the same radio equipment.

-multiple zone and a single base station make up a cell. Mobile travels within the cell it is served by the zone within the strongest signal and any base station channel may be assigned to any zone by the base station.