An Efficient Subcarrier Assignment Algorithm for Downlink OFDMA

In this paper, the rate adaptive optimization (RA) problem, which maximizes the sum of user data rates subject to total power constraint and individual guaranteed rates, is considered. Two tasks are commonly examined: bandwidth allocation and specific subcarrier assignment. A mechanism to provide a degree of fairness among users is coupled with the first task. Considering the second task, a novel algorithm, rate profit optimization algorithm (RPO), is defined to assign specific subcarriers to different devices of a multiuser downlink OFDM system. In RPO, a new approach is proposed to assign a conflicting subcarrier (best subcarrier for several users). This algorithm is shown to exhibit good results regarding spectral efficiency and fairness with a complexity significantly lower than the Hungarian algorithm.