Title: Cooperation decreases energy consumption in 802.11 networks
Authors: Sathya Narayanan, Shivendra Panwar (Poster II, 10)

ABSTRACT

Modifications to the 802.11 MAC protocol that enable cooperative transmissions have been proposed to improve network performance. In this work, we investigate the energy consumption of devices in a 802.11 network when high data rate devices cooperate with low data rate devices by assisting with their transmissions. However, such cooperation entails the expenditure of energy by high data rate nodes in the transmission of data for other nodes. Using analysis and simulation, we demonstrate that the total energy expended by all the nodes in the network reduces when cooperation occurs. Surprisingly, we also demonstrate that an individual high data rate node can reduce its own energy expenditure by forwarding data for other low data rate nodes. This seemingly counter-intuitive result is due to the fact that by forwarding another node's data, the high data rate node is able to complete transmission of its own data in a significantly shorter time interval due to a reduction in its idle time. This reduced time results in idle energy savings for the high data rate node that exceed the energy expended by it in forwarding third-party data. Based on these results, we conclude that cooperation in 802.11 networks leads not only to higher throughput but also reduced energy expenditure.