Adaptive Bit Partitioning for Reconfigurable Intelligent Surface Assisted FDD Systems With Limited Feedback

In frequency division duplexing systems, the base station (BS) acquires downlink channel state information (CSI) via feedback, which has not been adequately investigated in presence of RIS. this study, we examine limited feedback scheme by proposing a novel cascaded codebook and an adaptive bit partitioning strategy. The RIS segments between BS mobile into two sub-channels, each with line-of-sight (LoS) non-LoS (NLoS) paths. To quantize path gains, is proposed to be synthesized sub-codebooks whose codeword LoS NLoS components. This enables cater different distributions gains flexibly using bits design structure. On basis codebook, derive upper bound on ergodic rate loss maximum ratio transmission show that can cut down optimizing allocation during generation. minimize bound, propose strategy diverse environment system parameters. Extensive simulations are presented superiority robustness efficiency scheme.