Accelerating Resource Allocation for OFDMA Downlink with CNR Variation Over Users

This paper addresses the problem of resource allocation for orthogonal frequency division multiple access (OFDMA) downlink that aims at minimizing the total transmission power under data transmission constraints. To accelerate this multiuser resource allocation with small performance loss, an efficient technique is introduced that provides the power variation of single-user water-filling when the subcarrier assignment is changed. Based on this technique, an intelligent resource allocation method for OFDMA downlink is designed. First, a good starting point is determined by estimating the cardinality of the set of subcarriers that will be assigned to each user. Second, the convergence of the resource allocation is accelerated by reassigning those subcarriers first, which have the greatest channel-to-noise ratio (CNR) variation over the users. Compared to previous works, simulations show that the presented method provides an improved balance between performance and computational complexity.