K-Means Based Constellation Optimization for Index Modulated Reconfigurable Intelligent Surfaces

Reconfigurable intelligent surface (RIS) has recently emerged as a promising technology enabling next-generation wireless networks. In this letter, we develop an improved index modulation (IM) scheme by utilizing RIS to convey information. Specifically, study RIS-aided multiple-input single-output (MISO) system, in which the information bits are conveyed reflection patterns of rather than conventional amplitude-phase constellation. Furthermore, K-means algorithm is employed optimize constellation improve error performance. Also, propose generalized Gray coding method for mapping appropriate and analytically evaluate performance proposed deriving tight upper bound average bit rate (BER). Finally, numerical results verify accuracy our theoretical analysis well substantially BER RIS-based IM transmission scheme.