Joint relay assignment and channel allocation for energy-efficient cooperative communications

Cooperative communication (CC) has been proposed to achieve spatial diversity without requiring multiple antennas on a single device. Many efforts in exploiting the benefits of CC focus on improving the performance in terms of outage probability and channel capacity. However, the energy efficiency of CC, which is critical for the applications with energy constraints, has been little studied. In this paper, we study the problem of energy-efficient CC in cognitive radio networks by taking power control, relay assignment and channel allocation into consideration. We obtain the optimal power control for a single source-destination pair. After that, a heuristic algorithm is proposed to solve the the relay assignment and channel allocation problem for multiple source-destination pairs. Extensive simulations are conducted to show that the proposed algorithm can significantly improve the performance of energy efficiency over the direct transmission approach.