On energy efficiency of cooperative communications in wireless body area network

In this paper, we investigate the energy efficiency of cooperative communications in wireless body area network (WBAN). We first analyze the outage performance of three transmission schemes, namely direct transmission, single-relay cooperation, and multi-relay cooperation. To minimize the energy consumption, we then study the problem of optimal power allocation with the constraint of targeted outage probability. Two strategies of power allocation are considered: power allocation with and without posture state information. Simulation results verify the accuracy of the analysis and demonstrate that: 1) power allocation making use of the posture information can reduce the energy consumption; 2) within a possible range of the channel quality in WBAN, cooperative communication is more energy efficient than direct transmission only when the path loss between the transmission pair is higher than a threshold; and 3) for most of the typical channel quality due to the fixed transceiver locations on human body, cooperative communication is effective in reducing energy consumption.