Decision feedback estimation and tracking of carrier frequency offsets for ICI self-cancellation based OFDM systems

摘要

The intercarrier interference (ICI) self-cancellation schemes cannot apply to QAM-OFDM systems due to a constellation rotation caused by carrier frequency errors. We propose a decision feedback estimation (DFE) scheme, based on the self-cancellation scheme, to perform a simple and bandwidth-efficient estimation and tracking of the frequency offsets. The transmitted data symbols employed for ICI cancellation allows an initial estimation of frequency offsets. Then, the scheme switches to the tracking mode to carry out an estimation of deviations in the frequency offset. Finally, this fine-tuned estimate is applied to the ICI self-cancellation scheme for concurrently correcting the constellation rotation and reducing the ICI. Simulation results showed that our scheme allowed a random variation in the frequency offset up to 9%. Numerical examples in bit error rate performance evaluations of various OFDM receivers proved the effectiveness of the proposed scheme.