Energy-efficient cooperative communication with multi-relay contention and power allocation

In this paper, we propose an energy-efficient multi-relay contention and power allocation scheme. A new cooperative MAC scheme is introduced, in which multiple contention slots are employed for relay candidates to contend. To guarantee the energy efficiency under a required data rate, relay contention criteria is designed to select energy-efficient relay candidates. Transmit power then is optimally allocated among source and successfully contended relays to minimize the transmitting energy consumption. We also investigate how the number of relay contention slots affects the system performance. Simulation results show that our proposed scheme saves significant amount of energy compared with direct (non-cooperative) scheme.