Improved Channel Estimation for IRS-assisted mmWave Systems Exploiting Beam Leakage

Intelligent reflecting surface (IRS) is considered as a promising technology for mmWave communication systems. However, acquiring the channel state information (CSI) in such systems is challenging because of the high pilot overhead resulting from massive passive IRS elements. This paper discusses the cause and impact of the beam leakage which is caused by the mismatch problem between the beam width and the grid interval in the conventional compressed sensing based channel estimation (CE). Then, an improved orthogonal matching pursuit (IOMP) algorithm is proposed to improve the CE performance by utilizing the feature of the beam leakage. Simulation results show that the proposed algorithm can achieve better performance without extra computational complexity compared with existing schemes.