Date Added: Apr 2013
In this paper, the joint power and subcarrier allocation problem is solved in the context of maximizing the Energy-Efficiency (EE) of a multi-user, multi-relay Orthogonal Frequency Division Multiple Access (OFDMA) cellular network, where the objective function is formulated as the ratio of the Spectral-Efficiency (SE) over the total power dissipation. It is proven that the fractional programming problem considered is quasi-concave so that Dinkelbach's method may be employed for finding the optimal solution at a low complexity. This method solves the above-mentioned master problem by solving a series of parameterized concave secondary problems. These secondary problems are solved using a dual decomposition approach, where each secondary problem is further decomposed into a number of similar subproblems.