Two-way relay beamforming for sum-rate maximization and energy harvesting

Weighted sum-rate maximization with transmit power limit and energy harvesting constraints is considered in the context of two-way collaborative relay systems. We discuss an ideal scheme where the source nodes can decode information signal and harvest energy, simultaneously. An iterative algorithm based on semidefinite relaxation (SDR) and successive convex approximation (SCA) is developed to obtain (at least) a local optimal solution. In view of the limitation of the current circuits, we propose a practical ping-pong scheme wherein the source node can only perform one operation at a time. Furthermore, the iterative algorithm and its convergence are extended to such a case. The efficacy of the proposed algorithms is validated by numerical experiments.