Quantitative Analysis of Transmission Power Control in Wireless Ad-hoc Networks

In this paper, we address the issue of transmission power control in wireless ad-hoc networks. In general, it is assumed that minimum transmission power achieves the optimal throughput of an ad-hoc network because it produces minimum interference. However, this assumption can be realized under high node density which is not typical. Therefore, we show that using the minimal transmission range might not always results in optimal throughput performance. Using both throughput and throughput per unit energy as the optimization criteria, we demonstrate that the optimal transmission power is generically a function of the number of stations, the network size, and the traffic load. In particular, we observe that the optimal power is a function of the network load for typical network scenarios. To analyze these observations, we define an analytical throughput model using three factors: spatial re-use, hop count, and contention time. The throughput model supports the results of observations; throughput is proportional to transmission power in typical ad-hoc environments. Consequently, we conclude that the transmission power should be adjusted to the environment of ad-hoc networks in order to maximize the throughput performance