A novel iterative data-aided channel estimation for time domain synchronous-OFDM

The classical channel estimation method in TDS-OFDM is carried out based on the PN sequence in the GI which suffers from the intersymbol interference of the previous OFDM data symbols. This paper presents a novel data-aided channel estimation method to refine the initial channel estimation obtained from PN sequence. The data symbols are rebuilt based on the log-likelihood ratio (LLR) from the output of the demapper. The second channel estimation is made based on these data symbols. The moving average within the coherence bandwidth is performed on the second channel estimation to reduce noise. Finally, the initial and second channel estimations are combined according to the minimum mean square error (MMSE) criteria. The simulation results demonstrate that the proposed method can significantly improve the mean square error (MSE) performance of the initial channel estimator and the bit error rate (BER) performance of real TDS-OFDM based systems.