Capacity of Wireless Data Networks with Intra- and Inter-Cell Mobility

Abstract—The performance of wireless data systems has been thoroughly studied in the context of a single base station. In the present paper we analyze networks with several interacting base stations, and specifically examine the capacity impact of intraand inter-cell mobility. We consider a dynamic setting where users come and go over time as governed by random finite-size data transfers, and explicitly allow for users to roam around over the course of their service. We show that mobility tends to increase the capacity, not only in case of globally optimal scheduling, but also when each of the base stations operates according to a fair sharing policy. The latter approach offers the advantages that it avoids complex centralized control, and grants each user a fair share of the resources, preventing the potential starvation that may occur under a globally optimal strategy. An important implication is that a simple, conservative capacity estimate is obtained by ‘ignoring’ mobility, and assuming that users remain stationary for the duration of their service. We further demonstrate that the capacity region for globally optimal scheduling is in general strictly larger than the stability region for a fair sharing discipline. However, if the users distribute themselves so as to maximize their individual throughputs, thus enabling some implicit coordination, then a fair sharing policy is in fact guaranteed to achieve stability whenever a globally optimal strategy is able to do so.

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