A low complexity heuristic adaptive resource llocation algorithm for multiuser OFDM under rate constraints

Power minimization problem under minimum rate constraint for each user is studied in this paper for multiuser OFDM systems. By thoroughly analyzing the necessary conditions for the optimum solution of the resource allocation problem, we deduce a heuristic Lagrange relaxation (LR) based resource allocation algorithm. Different from existing LR schemes which obtain Lagrange multipliers through exhaustive search, we use the estimations of the Lagrange multipliers to guide the resource allocation and then revise the estimations according to the allocation result. By repeating the process the algorithm can achieve a good resource allocation strategy with a low complexity. Numerical results show that the proposed low complexity algorithm offers comparable performance with the exhaustive search algorithm and outperforms existing low complexity algorithms.