A Pilot-Free Estimation Method of Fading Channel for Satellite Communication Based on Limited Intercept Samples

Satellite radio signal interception and processing systems demonstrate distinct advantages in battlefield situational awareness, spectrum resource management, and non-cooperative target recognition. However, addressing the challenges of channel modeling for non-cooperative emitters (where active probing/calibration is infeasible and training data is scarce), this paper proposes a pilot-free estimation method for time-varying fading channels based on non-uniform angles of arrival. The method characterizes the non-uniform spatial distribution of scatterers using a truncated Gaussian distribution, determines multipath fading parameters through limited empirical sample fitting, and introduces a time-varying update cycle for dynamic tracking. This constructs a channel model tailored to satellite communication environments (sparse scatterers, non-uniform distribution, and rapid time-varying characteristics). Tests confirm that the proposed model achieves high consistency with power spectrum envelopes of actual channel measurements (corr=0.7522, MSE=0.0068, MAE=0.0354). Its key error metrics (MSE/MAE) rival those of neural network-based modeling approaches, while autonomously generating differentiated Doppler spectra that align with empirical data. These results validate that the method effectively characterizes transmission properties of non-cooperative satellite fading channels using only limited intercepted samples.