Base station energy cooperation in green cellular networks

This paper focuses on a network of renewable-energy-powered base stations where energy can be transferred across the network through power lines or wireless transfer. Specifically, we study a two-cell system with different numbers of cell users, and determine the direction and quantum of energy to transfer to maximize the sum-rate over all users when the energy transfer efficiency is η ∈ [0, 1]. We formulate this general problem under an FDMA configuration and solve it by a bisection search over the amount of energy to transfer ζ, where for each value of ζ a water-filling procedure is used to find the optimal power and bandwidth allocation. Both equal and optimal bandwidth allocation are considered, and the corresponding performance curves are plotted. A simple naïve approach is also proposed in which equal power and bandwidth allocation are used in each cell, and available energy per user in both cells is equalized through power transfer. Simulations show that the naïve approach performs reasonably well if η is high and channel gains are similar for all users.