Chapter 5

Multiradio Multichannel Opportunistic Routing

Two major factors that limit the throughput in multihop wireless networks are the co-channel interference and unreliability of wireless transmissions. Multiradio multichannel technology and opportunistic routing (OR) have shown their promise to significantly improve the network capacity by combating these two limits. It raises an interesting problem concerning the tradeoff between multiplexing and spacial diversity when integrating these two techniques for throughput optimization. It is not known what the capacity of the network could be when nodes have multiple radios and OR capability. In this chapter, we present our study on optimizing an end-to-end throughput of the multiradio multichannel network when OR is available. First, we formulate the end-to-end throughput bound as a linear programming (LP) problem, which solves the radio-channel assignment, transmission scheduling, and forwarding candidate selection problems together. Second, we propose an LP approach and a heuristic algorithm to find a feasible scheduling of opportunistic forwarding priorities to achieve the capacity. Simulations show that the heuristic algorithm achieves desirable performance under various number of forwarding candidates. Leveraging our analytical model, we find that 1. OR can achieve better performance than traditional routing (TR) under different radio/channel configurations, however, in particular scenario (e.g. bottleneck links exist between the sender and relays), TR is preferable; 2. OR can achieve comparable or better performance than TR by using less radio resource.