A simulation model of combined handoff initiation and channel availability in cellular communications

The problem of handoff in cellular communications has several components including: initiation and availability of channel resources. Often researchers consider these issues separately, but overall performance is determined by all. We devise a simulation model to consider the combined effects of these issues on the performance of handoff procedures. The model treats two adjacent base stations with fixed layout of highways and roads and considers fixed channel assignment for the cellular layout. The simulated propagation environment in the coverage area of the cells is generated using models that have been reported in the literature. They represent the received signal power by spatially correlated lognormal variates. The criteria for handoff initiation are based on received signal strength at sampling instants. Hysteresis is used to reduce unnecessary handoffs. Performance criteria of interest are: average number of handoff attempts per call, forced termination probability and blocking probability. Example performance characteristics obtained show relationships between average number of handoff attempts per call, forced termination and blocking probabilities, hysteresis level, and Erlang traffic. Trade-offs between average number of handoff attempts per call, forced termination probability and blocking probability are examined.