Energy efficiency of supportive relay with a novel wireless transmitter power consumption model

The energy efficiency of wireless communications, in terms of bits/Joule, is a metric which has come into focus of the research community. It can be improved if adaptive transmission power control (ATPC) and/or cooperative communications are used. We start from a novel model relating the transmit power (delivered to antenna) and total power consumption of the transmitter. We extend this model for use with ATPC, assuming that the transmitter knows the instantaneous channel loss. Using the extended model and assuming ATPC, we compare energy efficiency of the supportive relay (two-hop) and direct link (single-hop) for the same source-destination pair.We derive conditions on the transceiver parameters and channel losses over each link for which the supportive relay is more energy efficient than the direct link. It turns out that the channel losses over relay hops must be smaller than the direct link channel loss because of the power consumption nonlinearity and power consumption of transceiver electronics. The nonlinearity and the power consumption of transceiver electronics cause over 5dB penalty each.