Iterative Resource Allocation for Maximizing Weighted Sum Min-Rate in Downlink Cellular OFDMA Systems

This paper considers the downlink of a cellular orthogonal frequency division multi-access (OFDMA) system, in which multiple base stations (BSs) are coordinated by a centralized resource allocation algorithm. We address the problem of maximizing the weighted sum of the minimal user rates (WSMR) of coordinated cells subject to a total power constraint at each BS, in terms of jointly optimizing coordinated BSs´ subcarrier and power allocation. In particular, the solution of this problem corresponds to a resource allocation that guarantees similar rates to all users in each cell. An iterative algorithm is proposed to optimize the subcarrier allocation and the power allocation alternatively, so that the WSMR keeps increasing until convergence. In each iteration, the subcarrier allocation is updated by solving a mixed integer linear program for each cell, while the power allocation is updated by solving a successive set of convex optimization problems with a duality-based numerical algorithm. The effectiveness of the algorithm is illustrated by numerical experiments.