Multi-radio multi-channel routing metrics in IEEE 802.11s-based wireless mesh networks — And the winner is …

IEEE 802.11s is one of the emerging standards designed to build Wireless Mesh Networks (WMNs) which may serve to extend the coverage of access networks. The default IEEE 802.11s path selection protocol HWMP (Hybrid Wireless Mesh Protocol) is based on the radio-aware Airtime Link Metric (ALM) that outperforms the hopcount metric in single channel multi-hop wireless networks. However, this metric may lead to capacity degradation when multiple channels and/or multi-radio are used. To fully exploit the capacity gain of multiple channels use, new routing metrics have been proposed such as WCETT, MIC, iAWARE, EETT, and NBLC. These metrics distribute the data traffic load among channels and/or radios to reach the final destination. In this paper, we provide a qualitative comparison study that considers the characteristics of these metrics and a simulation-based performance analysis to identify the appropriate use cases of each one of them. For example, iAWARE is found to be more appropriate when there are lot of changes in interfering traffic, however WCETT and EETT are more efficient for low traffic in large networks configurations.