Perturbation-Resistant Transmit Beamforming

The Generalized Wigner–Smith (GWS) matrix enables the characterization of stationary aspects of wave scattering in a propagation environment. Eigenstates of the GWS matrix were recently shown to be invariant to a small change in a parameter of interest.Here, we use the GWS matrix eigenvectors for applications in multiple-input multiple-output (MIMO) wireless communications using antenna arrays for transmission and reception.The eigenvectors of the GWS matrix, also known as principal modes, are shown to be perturbation-resistant transmission channels. For the special case that the resulting MIMO transfer function is unitary, this also results in stationary Fisher information.In the numerical simulation study, we seek to maximize the received signal power, subject to a constraint on the tolerated MIMO transfer function perturbation. In this way, we achieve stable MIMO communication in the presence of small perturbations to the locations of scattering objects in the propagation environment.