Microcell zone concept

 Microcell zone concept 

Block diagram of microcell zone concept

• The problem associated with the sectoring technique is the increase in number of handoffs. This put an additional load on the switching and control link  elements of the mobile system. 
• A solution to this problem is based on the microcell concept for seven cell reuse as shown in Fig.
• In this scheme, all the three or more zone sites represented as Tx/Rx  in Fig. are connected to the among themselves.
• The tansmission media used for connecting the zones tothe base station are coaxial cable, fiber optics cable or a microwave link. So each cell consists of a base station and multiple zones.
• A mobile traveling within a cell, is served by the zone that has the strongest signal of all.
• As shown  Fig.  the antennas in zonee are placed at the outer edges of the cell and any base station  channel can be assigned to any zone by the base station. This proves to  be a better approach than sectoring.
• As a mobile travels from one zone to the other with in cell, it uses the same channel. This will avoid hand-oll, which is another advantage over the sectoring approach.
• Thus a given channel is being used only in a particular zone in which the mobile is travelling. So the base station radiates its power in a localized manner. 
• This will reduce interference. The channels are distributed in time and space by all the zones and are also reused in the co-channel cells. The microcell concept is very useful along highways or in the busy urban areas.

Advantages:

1.  Reduced co-channel interference.
2.  Improved signal quality.
3.  Increase system capacity.
4.  No degradation in the truncking efficiency.

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