Energy-efficient cooperative relay selection for UWB based body area networks

In this paper, an energy-efficient cooperative relay selection scheme is investigated for ultra-wideband (UWB) based wireless body area networks (WBANs). With a realistic nonlinear energy consumption model, the energy consumption for single-relay cooperation is established and the optimal power allocation for cooperation is derived accordingly to minimize the total energy consumption at a given relay location. Afterwards, an energy efficient relay selection criterion is described in detail. Simulation results verify the suitability of the criterion and show that, with the same desired spectral efficiency (SE), direct transmission is preferable for energy saving when the transmitter and receiver are located on the same side of the human body. However, at a suitable relay location and with large transmission distance, cooperative transmission can achieve a significant improvement on energy efficiency compared with direct transmission when the transmitter and receiver are located on the different sides of the human body.