Subject: Mobile Computing

Difficulty: Medium

Marks: 4 Marks

When sectoring is employed, lot of handoffs is required due to this load on switching and control link element of the mobile system increases.

• To solve this problem, a microcell concept for seven cell reuse is used.
• In this scheme, each of three (possibly more) zone sites are connected to single base station. The zone are connected by a coaxial, fibre optic cable or microwave link to a base stations.
• Multiple zones and single station make a cell. As mobile travels within a cell, it served by zone with strong signal.
• As mobile moves from one zone to another zone in same cell, it uses same channel, thus like a sectoring, handoff is not required at mobile switching centre (MSC) when mobile travels within the cell in different zone.
• The base station simply changes the channel from one zone to another zone, and channel is active in particular zone in which mobile is travelling, hence interference is reduced.
• The advantage of zone cell technique is that, cell maintains particular area of coverage, the co-channel interference in cellular system is reduced, as larger control base station is replaced by zone transmitter on edge of cell.