Precoding designs for energy efficiency balancing for the cellular two way relay network

This study investigates energy efficiency (EE) balancing precoding designs for the cellular two way relay network (CTWR). Owing to non-convexity and NP hard property of the worst case EE problem, the authors use convex approximation and convex relaxation to modify the problem for better mathematical tractability. The Dinkelbach-type method is adopted to solve the max-min fractional problem. Then alternating optimisation method is used to solve the inner subproblem as its non-convexity. After fixing the precoding of one station (base station or relay station), the subproblem is still non-convex. Then successive convex approximation (SCA) and semi-definite program relaxation methods are used to obtain the precoding matrices of BS and RS. The proposed algorithm, which can be extended to the two way relay system with direct link model or the one way relay system, has a wide range of application. Simulation results show that the proposed algorithm converges fast and achieves better EE balancing compared with existing method.