Fast Beam Search for IRS-Assisted Cellular Systems

A beam training protocol is required in millimeter-wave (mmWave) cellular systems with intelligent reflecting surface (IRS) to find the best beam pairs for the link between the base station (BS) and the IRS, as well as the link between the IRS and the mobile station (MS). This paper proposes fast beam training technique for IRS-assisted mmWave cellular systems to detect best beam pairs for BS-IRS and IRS-MS link. To distinguish simultaneously transmitted beams from the BSs in multi-cell multi-beam environments, two different types of beam training signals, (BTSs) are proposed: Zadoff-Chu sequence based BTS (ZC-BTS) and m-sequence based BTS (mBTS). The simulation results reveal that the proposed technique can significantly reduce the beam training time for IRS-assisted mmWave cellular systems.