IRMA: Integrated Routing and MAC Scheduling in Multi-hop Wireless Mesh Networks

This paper presents an integrated routing and MAC scheduling algorithm (IRMA) for improving system performance in multihop wireless mesh networks. The IRMA approach is motivated by the fact that conventional contention-based MAC protocols such as 802.11 do not perform well in combination with independent ad hoc routing protocols such as DSR, DSDV or AODV due to interactions between neighboring nodes in the network. In IRMA, a centralized algorithm is used to allocate resources to each flow based on traffic flow specifications and the network compatibility graph based on a generalized n-hop interference model. Joint routing and MAC eliminates contention between radio nodes and assigns traffic flows to alternate paths based on actual traffic demand, thereby providing significant increases in network capacity. Two alternative algorithms are described and evaluated using ns-2 simulations: 1) Link Scheduling with Min Hop Routing (IRMA-MH) which uses real-time flow information to select paths and to set up complete endto-end TDMA schedules; 2) Link Scheduling with BandwidthAware Routing (IRMA-BR) which uses local information about available MAC bandwidth to route around congested areas. Simulation results for both schemes are presented, showing up to 300% improvement in network throughput when compared with baseline 802.11-based multihop networks with independent routing.