An Adaptive Grouped Subcarrier Allocation Algorithm using Comparative Superiority

Abstract

In this paper, an adaptive grouped-subcarrier allocation algorithm using comparative superiority is proposed for the enhancement of system capacity and its simple implementation in a multiuser OFDM system. Since the computational complexity of the optimal subcarrier allocation algorithm based on the each subcarrier is extremely high, various sub-optimal algorithms have been developed for the realization of adaptive subcarrier allocation algorithm with the reduced complexity. Some of the promising sub-optimal algorithms are the blockwise and the decentralized allocation algorithms, which allocate subcarriers in groups instead of each subcarrier. The proposed algorithm is similar to the blockwise or the decentralized subcarrier allocation algorithm but all subcarriers are grouped according to the coherence bandwidth for the enhancement of system capacity. In addition, the proposed algorithm provides a simple solution for the conflict problem among users by reallocating only the conflicted groups and unassigned groups instead of reallocating entire groups. Furthermore, the comparative superiority concept, which swaps the groups between users if the system capacity is increased, is adopted in the re-allocation process for the enhancement of system performance. Simulation results demonstrate that the proposed algorithm increases the system capacity effectively over a static, an adaptive blockwise, and a decentralized subcarrier allocation algorithms