Throughput maximization of cooperative wireless mesh networks using directional antennas

Throughput maximization is a key challenge to numerous applications in wireless mesh networks (WMNs). As a potential solution, cooperative communications, which may increase link capacity by exploiting spatial diversity, has attracted a lot of attention. However, if link scheduling is considered, this transmission mode may perform worse than direct transmission in terms of end-to-end throughput, since the sending/receiving of cooperative relays incurs extra interferences. In this paper, we propose to employ directional antennas to alleviate those negative effects and comprehensively investigate the throughput maximization problem in cooperative WMNs. Regarding the features of cooperative communications and antenna modes (omnidirectional antennas or directional ones), we extend the links into cooperative links/general links, form an antenna based cooperative (ABC) conflict graph to characterize the interference relationship among those extended links, and design beamforming strategies w.r.t. link scheduling. Given all ABC independent sets in this graph, we mathematically formulate the end-to-end throughput maximization problem under cross-layer constraints and solve it by linear programming. Our simulation results show that the end-to-end throughput of cooperative WMNs can be notably improved, when transmission selection and antenna mode selection are jointly considered.