Effects of user mobility on handoff performance in a hierarchical cellular system

A personal communication system with hierarchical cellular overlays is described. Two strategies for traffic management are considered and compared. In strategy 1, the mobile stations are divided into two groups based upon their speed and then are served by different layers to minimize the handoff rate. In strategy 2, the mobile stations may enter either a layer regardless of their speed. It is shown that the probability of call attempts not completed is much smaller for strategy 1 than for strategy 2. We also discuss how to determine the threshold speed to keep the traffic balanced between the two layers. Analytical models are proposed to study the performance of the strategies. It is also found that the performance of strategy 1 is insensitive to imperfect speed estimation.