Second Order Rectified Parallel Factor Model Based Cascaded Channel Estimation in IRS-Assisted SWIPT System

Abstract

This paper investigates cascaded channel estimation in intelligent reflecting surface (IRS)-assisted simultaneous wireless information and power transfer (SWIPT) system. Multiple-input multiple-output (MIMO) transceiver structures combined with transmitter active beamforming and IRS passive beamforming are studied. Cascaded channel estimation is transformed into sparse signal reconstruction problem, and compressed sensing (CS) is applied to solve this problem. Only a small amount of training overhead provides reliable channel estimation gains as well as better beamforming gains. Second order rectified parallel factor (PARAFA) model is implemented in IRS-assisted SWIPT system, which is described by tensor decomposition method. The received signal can be represented by PARAFA model with algebraic structure and IRS phase shift. Two cascaded channel estimation approaches, namely, bilinear alternating least squares (BALS) and least squares Khatri-Rao factorization (LSKRF), are proposed respectively. Simulation results show that, compared with orthogonal matching pursuit (OMP) approach, the proposed BALS cascaded channel estimation approach obtains better normalized mean square error (NMSE) and convergence performance with the least parameter constraints.