Throughput and Energy Efficiency in Topology-Controlled Multi-hop Wireless Networks

In multi-hop wireless networks, various topology control algorithms have been proposed to reduce the transmission range of nodes based on local information and yet maintain a connected topology. In this paper, we design a framework for evaluating the performance of topology control algorithms using overall network throughput, and total energy consumption per packet delivered, as the metrics. Our goal is to identify the scenarios under which topology control improves the performance. We supplement our analysis with ns2 simulations based on an idealized version of the cone-based topology control algorithm [19], [11]. For unreliable link layer, we find that in lightly loaded scenarios, topology control can reduce the throughput significantly. However, using link layer retransmissions the throughput ratio can be brought back to 1. Under heavily loaded scenarios for large networks, the throughput can be improved by a factor up to k sup 2, where k is the average factor of reduction in transmission range using topology control. Studies of energy consumption reveal that improvements of up to k sup 4 can be obtained using topology control. However, these improvements decrease as the traffic pattern shifts from local to non-local. Beyond random traffic pattern, the benefit of topology control can be negligible or even worse. Thus, using analysis as well as simulations we clearly identify the scenario in which topology control may be used to improve network performance.