High Throughput Route Selection in Multi-rate Ad Hoc Wireless Networks

Modern wireless devices, such as those that implement the 802.11b standard, utilize multiple transmission rates in order to accommodate a wide range of channel conditions. Traditional ad hoc routing protocols typically use minimum hop paths. These paths tend to contain long range links that have low effective throughput and reduced reliability in multi-rate networks. In this work, we present the Medium Time Metric (MTM), which is derived from a general theoretical model of the attainable throughput in multi-rate ad hoc wireless networks. MTM avoids using the long range links favored by shortest path routing in favor of shorter, higher throughput, more reliable links. We present NS2 simulations that show that using MTM yields an average total network throughput increase of 20% to 60%, depending on network density. In addition, by combining the MTM with a medium time fair MAC protocol, average total network throughput increases of 100% to 200% are obtained over traditional route selection and packet fairness techniques.