Performance analysis of channel rate selection schemes in systems with tight reuse

Tight reuse GSM deployments are of interest to network operators facing spectrum constraints. In GSM cellular networks, half-rate channels are specified as a spectrally efficient alternative to full-rate channels for the support of voice services under favorable channel conditions. In this paper, we propose and analyze channel rate selection algorithms upon initial call setup. Four different algorithms are considered: (a) rate selection based on the serving sector signal strength measurements; (b) rate selection based on the signal strength and two-tiers of co-channel interference measurements; (c) rate selection based signal strength and dominant interferer measurement; and (d) hybrid approach that uses metrics reported by the terminal. i.e., either signal strength only or signal and interference measurements depending on the information that can be derived from the measurement report. Dynamic system level simulations show that for 1/3 reuse, these rate selection algorithms yield 32% to 51% capacity gain over systems employing only full rate channels; in 1/1 reuse, the gains are negligible with and without perfect cancellation of the dominant interferer.