An adaptive subcarrier allocation algorithm for multiuser OFDM system

A blockwise adaptive subcarrier allocation algorithm is presented in this paper which is for the downlink of the multiuser OFDM system. Assuming perfect knowledge of the channel information for multiple users, the algorithm minimizes the total required transmit power while satisfying multi-users' data rate and BER requirement. Here the total transmit power is subjected to a limit. The results of simulation show that the performance of the OFDM system with this algorithm improves approximately by 4 dB in average bit SNR compared with traditional OFDM-FDMA scheme in a multiuser Rayleigh fading environment. Additionally, the simulation also indicates that the proposed algorithm helps supporting more users although it is sensitive to the size of the block. As assigning subcarriers in block, the computational complexity of the algorithm is much lower than that of the "water-filling" algorithm, so it is a practical allocation algorithm.