5.6 Conclusions and Future Work

In this chapter, we proposed a unified framework to compute the throughput bound between two end nodes in multiradio, multichannel, multihop wireless networks when OR is available. Our model accurately captures the unique property of OR: throughput can take place from a transmitter to any one of its forwarding candidates at any instant. We also studied the capacity region of an opportunistic module and proposed an LP approach and a heuristic algorithm to obtain an opportunistic forwarding priority scheduling that satisfies a rate vector. Numerical simulations show that the heuristic algorithm achieves desirable performance under various number of forwarding candidates. It can satisfy the rate vector with unsatisfied rate ratio below 0.7% when there are no more than five forwarding candidates. Even when there are ten forwarding candidates, the unsatisfied rate ratio is below 10%. Our methodology can be used to calculate the end-to-end throughput bound of OR and TR in multiradio, multichannel, multihop wireless networks, as well as to study the OR behaviors (such as candidate selection and prioritization). Leveraging our analytical model, we gained the following two insights: 1. OR can achieve better performance than TR under different radio/channel configurations, however, in some scenario (e.g. bottleneck links exist between the sender to relays), TR can be preferable to OR.2. OR can achieve comparable or even better performance than TR by using fewer radio resources. We also confirm that just involving a few “good” forwarding candidates is enough to approach optimal throughput. As for future work, we are interested in designing practical distributed joint radio-channel assignment and opportunistic routing protocols in multiradio, multichannel systems based on our theoretical study and observations in this chapter.