Environment-Aware Codebook for Reconfigurable Intelligent Surface-Aided MISO Communications

Reconfigurable intelligent surface (RIS) is a revolutionary technology that can customize the wireless channel and improve the energy efficiency of next-generation cellular networks. This letter proposes an environment-aware codebook design by employing the statistical channel state information (CSI) for RIS-assisted multiple-input single-output (MISO) systems. Specifically, first of all, we generate multiple virtual channels offline by utilizing the location information and design an environment-aware reflection coefficient codebook. Thus, we only need to estimate the composite channel and optimize the active transmit beamforming for each reflection coefficient in the pre-designed codebook, while simplifying the reflection optimization substantially. Moreover, we analyze the theoretical performance of the proposed scheme. Finally, numerical results verify the performance benefits of the proposed scheme over the cascaded channel estimation and passive beamforming as well as the existing codebook scheme in the face of channel estimation errors, albeit its significantly reduced overhead and complexity.

Automated summary

Reconfigurable intelligent surface (RIS) is a groundbreaking technology that can customize wireless channels and improve energy efficiency in next-generation cellular networks. This study proposes an environment-aware codebook design using statistical channel state information (CSI) for RIS-assisted multiple-input single-output (MISO) systems. By generating multiple virtual channels offline and designing an environment-aware reflection coefficient codebook, the proposed scheme simplifies reflection optimization while optimizing transmit beamforming for each reflection coefficient in the pre-designed codebook. Theoretical analysis and numerical results demonstrate the performance benefits of the proposed scheme over existing methods in the presence of channel estimation errors, with reduced overhead and complexity.