At present, although the IEEE 802.11 MAC and PHY specifications provide multi-channel and multi-rate capabilities, exploiting data rates and available orthogonal channels is still a crucial issue to ensure high network performance in wireless mesh networks (WMNs). Most channel assignment schemes for WMNs assume that all links operate at an identical data rate; i.e., they ignore the existence of multi-rate sharing problem. However, high rate links suffer from throughput reduction due to interference from low rate links in a multi-rate network. This problem happens when transmission over low rate links consumes disproportionally more time and resources as compared to high rate links. To alleviate this performance anomaly, we first formulate an Effective Link Capacity function, which is a mathematical metric used to estimate the useful capacity of each channel after taking into account the level of performance anomaly and traffic information of the network. In addition, we propose a Capacity Based Data Rate-Aware Channel Assignment (CDRCA) algorithm to select the channel that suffers from the least degree of performance anomaly to improve the capacity of multi-rate multi-channel WMNs. Results obtained through extensive simulations show that CDRCA gives better performance in terms of aggregate network throughput over existing channel assignment schemes.
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