An insight into dynamic channel assignment in cellular mobile communications systems

Abstract

It is commonly believed that the dynamic channel assignment performs better than the fixed channel assignment under light traffic and under nonuniform traffic but performs poorly under a uniform, heavy load. Many dynamic assignment schemes have been investigated mainly via simulation due to the large dimensional complexity of the problem. The common characteristic of these schemes is that there is a set of dynamically assignable channels and that a channel is always assigned if one of these is free. This paper develops a queuing optimization model involving a single channel and a donor group and an acceptor group of cells. An explicit formula is derived for the value of the load below which the dynamic assignment of the channel from the donor group to the acceptor group minimizes the overall call blocking probability. It analytically validates the belief that a strategy for dynamically assigning channels should be sensitive to the load on the system and yields an important insight in that the dynamic assignment of channels should be disallowed in certain situations even if channels are free.