Green Resource Allocation and EE-Balancing in Multiuser Two-Way Amplify-and-Forward Relay Networks

In this paper, we investigate an energy-efficient joint subcarrier and power allocation algorithm for improving the worst energy efficiency (worst-EE)in multiuser two-way amplify-and-forward (AF)relay networks, that not only balances the EE of the two-way links, but also ensures the desired quality-of-service (QoS)of each user. In order to maximize the worst-EE, an EE-balancing optimization problem is formulated as the ratio of the spectral efficiency (SE)over the total network power consumption subject to a total transmit power and users' QoS constraints. Since the formulated primal problem is a non-convex fractional mixed binary-integer program, i.e., NP-hard to solve, thus a concave lower bound on the objective function and a series of convex transformations are applied to transform the problem into a tractable convex form. An iterative algorithm is proposed to achieve the optimal solution of the dual problem. We further propose an efficient, low-complexity suboptimal resource allocation algorithm. Simulation results demonstrate the effectiveness of the proposed iterative and suboptimal algorithms.