| Summary: | 碩士 === 國立政治大學 === 資訊科學學系 === 96 === A new promising wireless technology has emerged recently, called wireless mesh networks (WMNs). WMNs are an inexpensive way to provide wireless last-mile broadband Internet access and have all the advantages of ad hoc networks, such as self-organization, self-configuration. IEEE 802.11 MAC protocol has been adopted in 802.11s draft. Although IEEE 802.11 physical layer supports multiple rates, most researches assume single rate environment for simplicity. However, in reality, 802.11 adopts automatic rate fallback (ARF) multi-rate algorithm. In other words, the data rate will be automatically adjusted due to its signal-to-noise ratio, or error rate. Here, we assume the fitness of IEEE 802.11 over WMNs, and considering path capacity, delay, flow fairness, in multi-hop multi-rate environments. They all are affected by data rates on the links along the path. In order to address and improve the above issues, we propose a cross layer scheme which is modified by the contention window of IEEE 802.11 DCF MAC and weighted fairness scheduling mechanism. We point out the problem and find out the suitable solution via a series of scenarios simulations. The results show that if increasing the priority of the low data link and taking care about flow fairness problem, the capacity and delay will be improved.
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