Power Management of Cache-enabled Cooperative Base Stations Towards Zero Grid Energy

With the increasing demand of high speed mobile data transmission, densely deployed small cell base stations capable of caching popular contents have recently emerged as a promising technique to improve the quality of service for mobile users. In this paper, we investigate the cooperative transmission and power management problem for a set of "off-grid" base stations in a cellular network hierarchy that are powered solely by on-site renewable energy sources. The network throughput maximization problem is mathematically formulated as a mixed-integer non-linear programming problem. In the proposed formulation, a base station can adjust its transmission power in a coordinated multipoint communication scheme and/or switch to a "sleep mode" for energy saving. Based on the Lyapunov optimization theory, an efficient near-optimal solution method is proposed with provable bound of the optimality gap. Experimental results on a realistic setup show that the proposed algorithm can achieve up to 2.96x download throughput per user compared to some baseline algorithms.