Performance of distributed utility-based power control for wireless ad hoc networks

We study the performance of a distributed and asynchronous power control scheme for a spread spectrum wireless ad hoc network. The users exchange prices that reflect their loss in utility due to interference. The prices are then used to determine optimal (utility maximizing) power levels for each user. We present simulation results illustrating the convergence of the algorithm, and the effect of limited information. With logarithmic utilities, the pricing algorithm exhibits rapid convergence to the unique optimal power allocation. We then study the effect of limiting the amount of information users can exchange. Results are presented, which show performance (average utility per user) assuming each transmitter can decode interference prices only from receivers within a specified radius. The performance is shown to degrade gracefully as the radius decreases. We also compare the performance of the pricing algorithm with a Request to Send/Clear to Send (RTS/CTS) protocol. Numerical results show that in a dense network the pricing algorithm can offer large improvements in total efficiency (i.e., when utility corresponds to information rate). The effect of coarse rate control on performance is also examined.