Weighted adaptive threshold estimating method and its application to Satellite-to-Ground optical communications

In this paper, a weighted adaptive threshold estimating method is proposed to deal with long and deep channel fades in Satellite-to-Ground optical communications. During the channel correlation interval where there are sufficient correlations in adjacent signal samples, the correlations in its change rates are described by weighted equations in the form of Toeplitz matrix. As vital inputs to the proposed adaptive threshold estimator, the optimal values of the change rates can be obtained by solving the weighted equation systems. The effect of channel fades and aberrant samples can be mitigated by joint use of weighted equation systems and Kalman estimation. Based on the channel information data from star observation trails, simulations are made and the numerical results show that the proposed method have better anti-fade performances than the D-value adaptive threshold estimating method in both weak and strong turbulence conditions.

► The proposed method made use of the correlations of the signal samples and its change rates. ► The perpendicular wind velocity brought by orbital motion of the satellite was first analyzed. ► The correlations were described in the form of weighted equations (Toeplitz matrix). ► The method improved the sensibility of the trends of long and deep fades, and suppressed random noises. ► The proposed method has better anti-fade performances when combined with Kalman estimation.