Enhancing the throughput-delay performance of IEEE802.11 based networks through direct transmissions

Abstract

It has been advocated so far that operating at the lowest power level that keeps the network connected would achieve optimal throughput performance as the number of nodes in the network grows to infinity; a trend that has yet to be proved in practical ad hoc networks. Adopting this strategy might have a significant effect by deteriorating both throughput and delay performance in many practical situations. The main culprit is the relatively low spatial reuse factor one can attain in typical network topologies, even when operating at the lowest possible power levels. This, in turn, is due to the large carrier-sensing range adopted in most implementations of the protocol. In this paper, we prove that transmitting at the per-link-minimality condition (employing just enough power to reach the final destination directly in one hop) is always optimal from a delay-throughput perspective in most network sizes and traffic patterns of interest. In the cases where the final destination is out of the radio range of the transmitter, it is always optimal for the transmitter to employ the highest possible power level that would allow it to reach the destination in the least number of hops.