Nonpilot-aided carrier frequency tracking for uplink OFDMA systems

A carrier frequency offset (CFO) tracking scheme without the use of any pilot subcarriers for the uplink orthogonal frequency division multiple access (OFDMA) system is proposed in this paper. We first analyze the interference due to CFO in uplink OFDMA systems, then, an offset tracking scheme is presented. The proposed scheme employs multiple time-frequency decision-feedback carrier recovery loops for individual users to restore the original symbols. Moreover, a modularized and flexible structure design is achieved for a low-complexity implementation of the loop. Simulation results show that the proposed scheme is resistant to multipath fading, while the BER (bit-error-rate) performance is very close to that of an ideal reception system without CFO.