We study the call blocking performance obtained by microcellizing a macrocell network. Each macrocell is partitioned into microcells, and some of the channels originally allocated to the macrocell are assigned to the microlayer cells according to a reuse pattern. The arriving calls are classified as fast or slow; fast calls are always assigned only to macrocell channels, whereas for slow calls a microcell channel is first sought. Slow calls may be allowed to overflow to the macrolayer, but may be repacked to vacated microcell channels. Calls can change their mobility class during a conversation. We develop an approximate analysis for computing the slow and fast call blocking probabilities in such a system. We adopt the technique of analyzing an isolated macrocell with the Poisson arrival assumption and then iterating on the stationary analysis of the isolated macrocell to obtain stationary results for the multicell system. Simple, but accurate approximations are developed for analyzing the isolated macrocell and its associated microcells, The analyses based on the approximate isolated cell model are validated against simulations of a multicell model.
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