Power allocation and partner selection for energy efficient decode and forward cooperation in wideband wireless sensor networks

Optimum solutions of the power allocation and partner choice of cooperative wireless communications have been addressed in a considerable amount of literatures. However, most achieved results are based on the transmission over flat fading channels, while the wireless transmission channels in closed space should be considered to have the frequency-selective nature. These proposed solutions are not applicable for the cooperation in indoor wireless sensor networks. Therefore, in this paper, we investigate the energy efficient cooperation (i.e., decode and forward) in wireless sensor networks, with the AWGN channels affected by the frequency-selective Rayleigh fading. Analytical, low-complexity expressions of the optimal solutions of the cooperation are developed in terms of the transmit power allocation and partner selection. The investigation is based on a network geometry of a fixed source node and destination node with a range of potential partner locations. Simulation results indicate that the quality of transmission may be improved by considering the frequency-selective nature of the channels in WSNs in closed areas. Numerical results show that the nodes of the cooperative DF diversity in indoor WSNs consume less energy than that in WSNs under flat fading channels.