Power Allocation and Cooperation in Cell-Free Massive MIMO Systems with Energy Exchange Capabilities

In this paper, we investigate a cell-free massive MIMO system that is compromised of a large number of distributed access points (APs) powered by independent micro-grids, each with different prices. We enable this system with energy exchange capabilities in order to offset the power consumption cost. Moreover, we exploit the cooperation between the APs through energy exchange via a smart grid infrastructure in order to enhance the energy efficiency of massive MIMO systems. Hence, the problem of total grid power consumption minimization has to be solved by efficiently managing the power delivered from different sources while satisfying the system requirements in terms of user quality of service demands. This paper solves the optimal power cooperation and allocation problem using linear programming. In addition, the optimal power allocation problem is solved when neglecting cooperation between APs. Next, a joint AP selection and user scheduling algorithm is devised ensuring the feasibility of the problem. Finally, simulation results show that the proposed power cooperation technique allows to significantly enhance the energy efficiency of cell-free massive MIMO systems.