Optimal channel assignment in cellular networks with non-homogeneous demands

Abstract

This paper deals with the channel assignment problem (CAP) in a hexagonal cellular network with 2-band buffering, where the interference does not extend beyond two cells. Here, we first present new lower bounds on the required bandwidth for a cellular network with homogeneous demand /spl omega/, for various relative values of s/sub 0/, s/sub 1/, and s/sub 2/, the minimum frequency separations required to avoid interference for calls in the same cell, or in cells at distances one and two respectively, where s/sub 0//spl ges/s/sub 1//spl ges/s/sub 2/. Next we present some novel strategies for assigning channels to the cells of the entire cellular network with a homogeneous demand w using a genetic algorithm. We then show how these strategies for homogeneous demand can be extended to the cases with nonhomogeneous demand vector W=(w/sub i/), where w/sub i/ represents the channel requirement for cell i. Most interestingly, it shows that in some cases depending on s/sub 0/, s/sub 1/ and s/sub 2/ the required bandwidth is mainly determined by the maximum demand w/sub max/ in W. It shows that in terms of bandwidth requirement the case is almost equivalent with cellular networks having homogeneous demand w/sub max/. The technique also results optimal bandwidth solutions for all the eight well-known benchmark instances including the most difficult two.