A Time Domain Inverse Matrix Receiver for CFO Suppression in WIMAX Uplink System

In orthogonal frequency division multiple access (OFDMA) uplink system, orthogonal multiple subcarriers are assigned to different users for parallel high data rate communications. However, carrier frequency offset (CFO), which is mainly due to oscillator mismatches and/or Doppler shift, will destroy the orthogonality among subcarriers and introduce intercarrier interference (ICI) as well as multiple-access interference (MAI) in uplink scenario. Thus, system performance will be seriously degraded. To overcome this problem, it is of great importance to do research on suppression of the interferences caused by CFO. In this paper, we proposed a novel time domain inverse matrix receiver to suppress the interference of multiple CFOs. Compared with the conventional frequency domain direct ZF inverse matrix method, which has high complexity in obtaining the ICI matrix and its inverse matrix, the proposed method has very low complexity in obtaining the interference matrix. Furthermore, the signal after interference suppression is a frequency domain signal. Thus the receiver complexity can be simplified. Simulation results show that this algorithm has almost the same performance to the frequency domain direct ZF inverse matrix method.