Resource allocation in rate-limited OFDMA Systems: A hybrid heuristic approach

This paper presents a novel resource allocation procedure for OFDMA downlinks, which stems from an hybridization of the Harmony Search and the Differential Evolution heuristic algorithms. In this setup it is known that optimum subcarrier and power allocation is achieved through 1) assigning each subcarrier to the user with highest channel gain at the given frequency, and 2) a Water-Filling procedure over the set of considered channel gains. This work addresses the scenario where stringent rate constraints are imposed for each user at the transmitter, scenario where the previous optimum resource allocation procedure no longer holds. The proposed iterative technique hinges on the aforementioned combinatorial heuristics, jointly with an iterative greedy subcarrier shifting procedure that accounts for the fulfillment of the established rate restrictions. Preliminary simulation results are provided for the extended vehicular ITU channel model, which shed light on the performance of the proposed allocation procedure.