Differential Data-Aided Beam Training for RIS-Empowered Multi-Antenna Communications

The Reconfigurable Intelligent Surface (RIS) constitutes one of the prominent technologies for next generation wireless communications. It is envisioned to enhance signal coverage in cases when direct link communication weak. Recently, beam training based on codebook selection proposed obtain optimized phase configuration RIS. After that, data transmitted and received by using classical coherent demodulation scheme (CDS). This approach able avoid large overhead required channel sounding process, it also circumvents complex optimization problems. However, still requires transmission some reference signals test different configurations codebook, best codeword chosen according measurement energy signals. Then, due reduces spectral efficiency. In this paper, a zero RIS proposed, relying reception non-CDS (NCDS). At BS, differential can be used determination Therefore, efficiency system significantly enhanced since are fully avoided. choosing NCDS more suitable transmit information high mobility scenarios as compared CDS. Analytical expressions Signal-to-Interference Noise Ratio (SINR) non-coherent RIS-empowered presented. Moreover, detailed comparison between CDS terms complexity given. extensive computer simulation results verify accuracy presented analysis showcase that outperforms existing solutions.