Improved channel estimation algorithm for OFDM over LEO channels

For the study of OFDM (Orthogonal Frequency Division Multiplexing) system for LEO (Low Earth Orbits) satellite communication, a channel estimation algorithm by Kalman filtering based on comb-type pilot subcarriers is proposed in this paper. Due to the statistical characteristics of LEO channel, an OFDM system model on the frequency domain is derived and the correlation of the process noises in Kalman filtering between two consecutive identical signals at the same pilot subcarrier are modeled as the first Markov chain. The performance of the proposed method is compared with LS (Least Square) channel estimator by measuring bit error rate (BER) with QPSK, BPSK, 8-PSK and 16QAM as modulation schemes. The simulation results illustrate the effectiveness of the proposed algorithm.