A robust ranging detection with MAI cancellation for OFDMA systems

During the initial uplink synchronization, the BS communicates with MSs to adjust timing and power offsets. The common method to achieve the objective is to use the orthogonal code in the frequency domain for OFDMA systems. Due to the timing offset, the orthogonality of codes is decayed and multiple access interference (MAI) becomes serious. In order to decrease this influence, we proposed the idea which combines the channel estimation and the multiuser detection. On the strength of cancelling the MAI step by step, ranging users can be detected one by one. The proposed idea is robust to achieve a significant improvement on the ranging detection rate over the multipath Rayleigh fading channel.