Channel Estimation for Intelligent Reflecting Surface Assisted Backscatter Communication

Intelligent reflecting surface (IRS) is a promising technology to improve the performance of backscatter communication systems by smartly reconfiguring multi-reflection channel. To fully exploit passive beamforming gain IRS in communication, channel state information (CSI) indispensable but more practically challenging acquire than conventional IRS-assisted systems, since passively reflects signals over both forward and backward (backscattering) links between reader tag. address this issue, we propose letter new efficient estimation scheme for system. minimize mean-square error (MSE) estimation, formulate solve an optimization problem designing training reflection matrix under constraints unit-modulus elements full rank. Simulation results verify effectiveness proposed as compared other baseline schemes.