Frequency and Power Allocation of OFDM Systems with proportional rate constraints

A two-step solution to the problem of finding the sub-channel and power allocation that maximizes the energy efficiency of the OFDMA based transmissions from a base station, under proportional rate and total power constraints, is presented. A low complexity sub-channel assignment is followed by an optimal power allocation that is obtained via a single nonlinear equation. The proposed algorithm has the same computational complexity as the best algorithm in the literature for the same problem but with minimum rate constraints. While the convergence of the algorithm in the literature is not guaranteed, the algorithm in this paper is proven to converge. Simulation results show that the proposed algorithm out-performs the one in the literature when the rate constraints are ignored.