CoMP meets energy harvesting: A new communication and energy cooperation paradigm

In this paper, we pursue a unified study on energy harvesting and coordinated multi-point (CoMP) enabled wireless communication by investigating a new joint energy and communication cooperation approach. We consider a practical CoMP system with clusters of multiple-antenna base stations (BSs) each powered by hybrid power supplies (including both the conventional grid and renewable energy sources) cooperatively transmitting to multiple single-antenna mobile terminals (MTs). We propose a new design paradigm termed energy cooperation among BSs within each cluster, which share energy for more efficient cooperative transmission via injecting/drawing power to/from the grid with a zero-sum net energy transfer. We maximize the downlink sum-rate for all MTs in one particular CoMP cluster with cooperative zero-forcing precoding at BSs subject to a new type of transmit power constraints featuring energy cooperation among BSs with a given loss ratio. To jointly optimize the precoders at BSs and the amount of energy transferred among them, we propose an efficient algorithm by applying the techniques from convex optimization. By simulations, we show that the proposed joint communication and energy cooperation solution substantially improves the downlink throughput for energy harvesting CoMP systems, as compared to suboptimal designs without communication and/or energy cooperation.