星地通信中基于压缩感知的OTFS信道估计OA北大核心

In view of the high dynamic channel characteristics of low Earth orbit(LEO)satellite-ground communication,a two-phase channel estimation method based on orthogonal time frequency space(OTFS)modulation is proposed.The proposed method achieves precise estimation of three parameters:delay,Doppler frequency shift,and channel gain with low pilot cost and high accuracy.The Two-phase Channel State Information Estimation(TP-CSIE)scheme adopts a time domain training sequence(TD-TS)as the pilot structure to solve the excessive pilot overhead problem of embedded pilot scheme in the delay-Doppler(DD)domain for the high dynamic satellite ground links.Due to the inherent sparsity of DD domain channels,the OTFS channel estimation problem is transformed into the recovery problem of sparse signals.In the first stage of the algorithm,the sparse signal recovery algorithm is chosen for the initial estimation of the channel parameters,and the overlapping addition(OLA)method is designed to obtain partial prior information for improving the accuracy of the compressive sampling matching pursuit(CoSAMP)algorithm.In the second stage of the algorithm,the enhanced rotationally invariant subspace algorithm is designed to realize the accurate estimation of channel parameters.The simulation results show that,the proposed algorithm has a normalized mean square error(NMSE)performance improvement of about 7 dB and a bit error rate(BER)performance improvement of about 10 dB,compared with existing schemes.