Load Aware Routing in Wireless Mesh Networks: Which is the Right Metric?
Nemesio A. Macabale · 2017
With increase in size of wireless mesh networks so are problems on interference, load-imbalance, and congestion that lowers throughput significantly. Proposals to solve issues related to this problem include accurate accounting of the channel load so that traffic can be directed along calmer regions of the networks reaching destination in time. Load aware routing metrics have been proposed for this purpose and the interface buffer queue (IFQ) occupancy seemed to be the most preferred basis even until recently. Others used it in combination with the contention window (CW) levels. We perform an analysis of load-based routing metrics based on these parameters and perform extensive simulation experiments in order to find out which is the appropriate metric to use and under what conditions. Despite its popularity, we show that metrics based on the interface buffer queue occupancy and contention window level were not good bases for load accounting because these metrics do not vary with traffic load despite their ability to sense saturated regions. Routing simulations show that routing based on IFQ would behave similar to hop counts and no adaptation and performance improvement is achieved. Our study suggests that a careful consideration of these limitations is essential, and provides insights on the applicability of these metrics. As an alternative we present the channel load metric (CLM) that accurately accounts for channel load, contention, and interference. Simulations show, it improves routing performance better than hop count and other load aware routing metrics found in the literature.