Subgradient Approach for Resource Management in Multiuser OFDM Systems

This paper studies the problem of finding an optimal subcarrier and power allocation for downlink communication in the orthogonal frequency division multiplexing (OFDM) wireless systems. With the constraints on the power consumption and transmission rates for users, the problem of maximizing total throughput is mathematically formulated. The developed mathematical model is so general as to include almost of existing ones in which the original problems have been usually divided into smaller and tractable ones to make a practical application of some simple greedy algorithms. In this study, developed is the subgradient dual optimization method for the problem. Extensive experiments with realistic data show that in a reasonable time the subgradient method converges to the stable point, almost feasible to the original problem. We proved that the subgradient method is applicable to the dynamic resource allocation, by showing that environmental changes at a stable state need much lesser additional iterations to converge.