Load-sensitive transmission power control in wireless ad-hoc networks

Transmission power control in ad-hoc networks has hitherto been used only for achieving connectivity of networks. It has been implicitly assumed that the optimal throughput performance in ad-hoc networks can be achieved when using the minimum transmission power required to keep the network connected. However, in this paper we argue that such an assumption remains valid only under high node densities, which is not the characteristic of typical ad-hoc networks. Using both throughput and throughput per unit energy as the optimization criteria, we demonstrate that the optimal transmission power depends on several network characteristics such as the number of stations, the network grid area, and the traffic load. In particular, we show that the optimal power is a function of the network load for typical network scenarios. Finally, we propose two transmission power control algorithms called common power control (CPC), and independent power control (IPC) that adjust the transmission power adaptively, based on the network conditions to optimize throughput performance. Simulation results show that both adaptive power control algorithms achieve better throughput per unit energy than constant power control.