IRS-aided Indoor Millimeter-wave System: Near-field Codebook Design

Intelligent reflecting surface (IRS) can be utilized to assist the millimeter-wave (mmWave) communication. In this paper, we consider an indoor IRS aided mmWave communication scenario, where the mmWave base station (BS) is located close to the IRS and the user equipment (UE). Different with the conventional system that the signal transmits over a few hundred meters, the indoor system only has a range of several meters. Therefore, the indoor mmWave channel cannot be approximated by conventional far-field planar channel model. Moreover, the IRS is hard to focus on the exact UE position due to localization error. Based on the near-field channel expression, we in this paper design an IRS refined training codebook with UE localization information. A sub-region mapping based training method is proposed to match the IRS reflections and UE localization region. Simulation results verify the effectiveness of proposed design.