Performance evaluation of a personal communication system in an urban environment

The advent of personal communication systems in metropolitan areas will require deployment of microcellular base stations serving the most congested areas, and of an overlying layer of cells (called umbrella cells or macrocells) covering the whole area in order to guarantee the continuity of service throughout the city. The management of spectrum resources in this mixed-cell environment requires a different approach than in conventional cellular schemes, mainly for the heavier signaling traffic load due to the higher hand-over rates. The authors focus on the relationship linking hand-over rates to the frequency channel allotment between microcells and macrocells. It is shown how the increase of the fraction of channels allocated to the microcells yields two opposite effects: a benefit related to the increase of system capacity and a cost due to the increase of hand-over rates. The final channel allotment is a tradeoff between these effects