Channel estimation method for time-varying channel based on periodic PN sequence for OFDM systems

Aimed at the performance reduction in OFDM time-varying channel for more numbers of sub-carriers, a novel periodic PN sequence based on pilot-assisted time-varying channel estimation method is proposed. Considering the fact that the energy of periodic sequence mainly concentrates on a few frequency points, at transmitter, the discrete pilot tones can be inserted into the data sequence in the frequency; at receiver, after the continuous pilot sequences are recovered, the auto-correlation calculation between it and the local PN sequence is made, thus, the noise impact on pilot is greatly reduced in time domain, and the accuracy of channel estimation is increased efficiently. The simulation results that the channel estimator with the proposed algorithm improves the mean square error (MSE), bit error ratio (BER) and bandwidth efficiency performances, especially in the more number of the sub-carriers and low signal noise ratio (SNR) circumstances.