Opportunistic medium access control in MIMO wireless mesh networks

As a newly emerging technology with some inherent advantages over other wireless networks, wireless mesh networks (WMNs) have received much attention recently. In this paper, we present a cross-layer protocol design for WMNs, which combines the MIMO technique in the physical layer and the opportunistic medium access in the MAC layer into an integrated entity and jointly considers their interactions. In particular, we propose a protocol named opportunistic medium access control in MIMO WMNs (OMAC-MWMN). In an infrastructure/backbone WMN, mesh routers are grouped into clusters, in each of which a cluster head has multiple pending links with its neighbors. This traffic-driven clustering provides a great opportunity for a cluster head to locally coordinate the multiuser medium access. In each iteration of the scheduling, a cluster head opportunistically chooses some compatible neighbors among multiple candidates by utilizing the benefits of multiuser diversity. Then the cluster head simultaneously communicates with multiple selected compatible neighbors through multiuser spatial multiplexing. We formalize the problem of finding a scheduler for a cluster head to select compatible neighbors as finding a compatible pair with the maximum SINR (signal-to-interference and noise ratio) product. Our simulation results show that the proposed protocol can significantly improve system capacity with minimum extra overhead.