Joint channel assignment and space-division multiple access scheduling in wireless mesh networks

In recent years, wireless mesh networks (WMNs) have been widely deployed to provide wireless access to the Internet. However, due to inter-link interference, the aggregated capacity of WMNs is limited, even with multiple channels. As a result, many links in WMNs are suppressed since interfering links cannot be active (i.e., transmitting packets) simultaneously. In this paper, we propose a joint design of channel assignment and space-division multiple access (SDMA) technique with the objective of maximizing the number of active links in WMNs. We assign different channels to transmission links based on their interference relationship to alleviate the interference. We also apply the SDMA technique to link scheduling, which enables two interfering links that share the same destination to communicate simultaneously on the same channel. By utilizing SDMA, more concurrent transmission links can be accommodated such that the network capacity can be greatly improved. We formulate this joint design into an optimization problem, prove its NP-hardness and then provide two heuristic algorithms to give practically solutions to the problem. Our simulation results demonstrate that the performance of the two heuristic algorithm is close to the optimal solution, and when 90% of SDMA pairs are compatible, the proposed algorithms can increase the percentage of active links in a WMN by up to 40% as compared to non-SDMA schedules.