Joint Iterative Channel Estimation and Symbol Detection for Orthogonal Time Frequency Space Modulation

A joint channel estimation and message passing (MP) data detection receive scheme is proposed for orthogonal time frequency space (OTFS) system in this paper. First, in order to mitigate inter-Doppler interference, we treat the interference from data as Gaussian variables, whose means and variances are fed back from MP detector. Secondly, based on the priori information on the channel, we derive a maximum a posteriori (MAP) delay-Doppler bins detection method to extract the proper position of the channel taps. Thirdly, in order to circumvent the performance loss incurred by the conventional least squares channel estimation, a novel minimum mean square error (MMSE) delay-Doppler domain channel estimator is constructed, which utilized the information both from the channel power delay profile and the Doppler spectrum. Simulation results show that the proposed algorithm performs better than the conventional algorithm in literature both in terms of the channel estimation accuracy and the bit error rate performance at the cost of less guard symbols.