Energy efficiency of cooperative device-to-device communication

Cooperative D2D communication is able to achieve spatial diversity without requiring multiple antennas on the same node. Many efforts in exploiting the benefits of cooperative communication focus on improving the performance in terms of outage probability or channel capacity. However, the energy efficiency of cooperative D2D communication, which is critical for the mobile devices with energy constraints, has been little studied. In this chapter, we study the lifetime maximization problem for multiple D2D pairs using CC in multi-channel wireless networks by an optimal dynamic allocation of resources in terms of power, channel, cooperative relay, and transmission time fraction. We prove it NP-hard and formulate it as a mixed-integer nonlinear programming (MINLP) problem, which is then transformed into a mixed-integer linear programming (MILP) problem using linearization and reformulation techniques. By exploiting several problem-specific characteristics, a time-efficient branch-and-bound algorithm is proposed to solve the MILP problem. Extensive simulations are conducted to show that the proposed algorithm can significantly improve the performance of energy efficiency over existing solutions.