Fair power allocation for sum-rate maximization in multiuser OFDMA

Multiuser OFDMA is a promising multiaccess technique for serving users with many non-interfering resources. In the present paper, the problem of the optimum power allocation for maximizing the sum rate with total fairness and total power constraints is tackled. If the sum rate would be a priori known, it could be simply distributed uniformly among the users. Then for each user, the minimum required power for obtaining the given rate can be easily found in a closed form using convex optimization techniques. The bisection method can be applied for finding the maximum sum rate that satisfies the total power constraint. The performance of the proposed method is investigated by simulations. The results show that there is an absolute loss in the sum rate independent of the number of resources per user as compared to waterfilling. Additionally, it is shown that our method is significantly better than waterfilling in typical scenarios in terms of the outage capacity.