Optimal Relay Station Placement with Non-uniform User Distribution

An relay station (RS) is a low-cost alternative to upgrading a conventional communication infrastructure. It can cope with ever-increasing wireless traffic demand and eliminate shadow areas efficiently. Accordingly, relay-based networking is a key technology for the next generation wireless communication infrastructure. In a relay-based network, the signal to interference plus noise ratio (SINR) and the throughput of the mobile stations (MSs), especially those located at cell edges, heavily depend on the location of the RSs. Hence, it is important to determine the optimal RS locations. In this paper, we address an anomaly which causes a serious fairness problem among MSs when the RS locations are determined only by throughput maximization. Moreover, RS locations were considered for a non-uniform geographical user distribution environment, because in the real world users are not uniformly distributed. We propose a utility optimal RS placement scheme based on a genetic algorithm (GA), which considers both the fairness problem and the non-uniform user distribution. An extensive simulation study verified that the proposed scheme extends cell coverage and maximizes utility while guaranteeing fairness among MSs.