Effects of sectorization on the spectrum efficiency of cellular radio systems

The effects of sectorization on the spectrum efficiency of a cellular system at different values of cell radius are studied. For a given cluster size, sectorization provides a higher signal-to-interference (S/I) ratio but reduces the spectrum efficiency of the system. It is demonstrated that it is possible to achieve higher spectrum efficiency by reducing the cluster size in a sectorized system without lowering the S/I ratio below the minimum requirement. In this respect, under both shadowing and nonshadowing conditions, there is an increase of spectrum efficiency of the sectorized systems over the omnidirectional system. The consistent gain in efficiency occurs when the cell radius exceeds a certain value depending on the traffic density in the cell