Load-Based Route Discovery Through Searching Range Adaptation for MANET Throughput Improvement

Traditional routing protocols designed for multihop wireless networks, e.g., the mobile ad hoc network (MANET), select a route with the smallest hop count. The end-to-end throughput in the route may not be the maximum when the network has multiple link data rates, as a small hop number implies a large geographic distance (link distance) for each hop. Due to the radio signal attenuation, this results in a low SNR at the receiving node and, consequently, a low available link data rate. Reducing the link distance by using routes with more hop counts can increase the link data rate. However, this may not necessarily improve the end-to-end throughput because more nodes have to be included in the routes. In this paper, we first investigate and analyze the impact of link distance on end-to-end throughput in multirate multihop wireless networks. Analysis and simulation results show that changing the link distance affects the network throughput. To achieve a high network throughput, a proper link distance requirement has to be set for each hop, depending on different parameters such as load density. Based on this finding, we then propose a crossing-layer adaptive searching range (ASR) routing algorithm. ASR can be integrated into existing routing protocols. According to the local network load density, ASR can help improve the network performance by adjusting the link distance in the routes.