Max-min lifetime optimization for cooperative communications in multi-channel wireless networks

Cooperative communication (CC) has been proposed for achieving spatial diversity without requiring multiple antennas on the same node. Many efforts in exploiting the benefits of CC focus on improving the performance in terms of outage probability or 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 lifetime maximization problem for multiple source-destination 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.