A low complexity power allocation algorithm in OFDM based decode and forward relay systems

This paper addresses the problem of the power allocation in OFDM-based DF relay systems. We develop a novel low complexity scheme for subcarrier allocation, where the objective is to maximize total transmission rate. For this purpose, the problem is solved in two steps, where in the first step, the rate on each subcarrier is maximized with the assumption that each subcarrier has the limited power. As a result, the capacity function is simplified and the source and relay power related to the limited power of each subcarrier is calculated. In the next step, by using the result of the previous step, the total power of subcarriers that maximizes the total sum rate is obtained. To evaluate the accuracy of the proposed method, we compare its accuracy through simulations with the optimal solution. Simulation studies indicate that the proposed method achieves more than 98% sum rate of the optimal solution.