Low complexity resource allocation algorithm by multiple attribute weighing and user ranking for OFDMA systems

In this paper, we propose an effective subcarrier allocation scheme for multiuser orthogonal frequency division multiple access (OFDMA) system in the downlink transmission with low computational complexity. In the proposed scheme, by taking multiple attributes of a user channel, such as carrier gain decrease rate and variation from the mean channel gain of the system, to determine a rank for the user, subcarriers are then allocated depending on the individual users' rank. Different channel characteristics are used to better understand a users' need to subcarriers and hence determine a priority to user. We also adopt an attribute weighing scheme to enhance the performance of the proposed scheme. The scheme is efficiently computational, by avoiding using iterations for the algorithm convergence and also common water-filling calculations which might become complex with increasing system parameters. Low complexity is achieved by allocating subcarriers to users depending on their determined rank. Our proposed scheme is simulated in comparison with other mathematically efficient subcarrier allocation schemes as well as with a conventional greedy allocation scheme. It is shown that proposed method demonstrates better results than the simulated schemes.