Microcellular communication systems with hierarchical macrocell overlays: traffic performance models and analysis

A hierarchical overlaid scheme suitable for high-capacity microcellular communications systems is considered as a strategy to achieve high system performance and broad coverage. High-teletraffic areas are covered by microcells while overlaying macrocells cover low-teletraffic areas and provide overflow groups of channels for clusters of microcells. New calls and handoff calls enter at both the microcell and macrocell levels. Handoff calls are given priority access to channels at each level. The layout has inherent load-balancing capability, so spatial teletraffic variations are accommodated without the need for elaborate coordination of base stations (wireless gateways). An analytical model for teletraffic performance (including handoff) is developed. Theoretical performance characteristics that show carried traffic as well as blocking, handoff failure, and forced termination probabilities are derived. Effects of nonuniform teletraffic demand and channel allocation strategies on system performance are discussed