Chebyshev Polynomials for Angular Power Spectrum Recovery

This paper introduces a novel framework using Chebyshev polynomials to reconstruct the continuous angular power spectrum (APS) from channel covariance data. The approach transforms the ill-posed APS inversion into a manageable linear regression problem, offering advantages in accuracy and enabling downlink covariance prediction from uplink measurements. The use of Chebyshev polynomials allows for effective control of approximation errors and the incorporation of smoothness and non-negativity constraints, making it a valuable contribution to covariance-domain processing in multi-antenna systems.