Novel Iterative Channel Estimation Method for DTMB System

Compared with the classical cyclic-prefix OFDM (CP-OFDM), PN sequence is chosen as guard interval in the novel transmission scheme time-domain synchronous OFDM (TDS-OFDM) system. Without pilot symbols, channel estimation in TDS-OFDM system is carried out based on the exploitation of the PN sequence and consequently suffers from inter symbol interference (ISI). In this paper, an iterative subtraction channel estimation method is proposed. By storing the last and the current received signal frames in a buffer, residual inter symbol interference caused by last received signal frame can be removed iteratively which makes the current PN sequence ISI-free and improves the precision of channel estimation significantly. The numerical simulation results show that the iterative method can improve the SNR performance of TDS-OFDM system effectively even in multipath environments with long-delay and large amplitude echoes.