A Low Complexity Combination Permutation Index Differential Chaos-Shift-Keying Scheme Based on Reconfigurable Intelligent Surface

This paper proposes an index modulation scheme assisted by the reconfigurable intelligent surface (RIS). This scheme utilizes RIS to assist signal propagation and is applicable to wireless propagation environments with obstacles. The data is segmented and permuted in a combinatorial manner to obtain significant advantages in terms of system complexity, energy transmission efficiency, and data security. Each transmission frame is divided into several permutation blocks of equal length. The first permutation block transmits the reference signal, and the subsequent permutation blocks all transmit the indexed data carriers. Due to the autocorrelation of chaotic signals, at the receiving end, all permutation versions of the reference signal are correlated with multiple data carriers respectively. The index estimate output by the single maximum amplitude correlator corresponds to the mapping bit of the data carrier, and the output results of multiple maximum amplitude correlators are summed up to estimate the modulation bit. This scheme consists of a base station side (BS), a reconfigurable intelligent surface (RIS), and a user terminal (UT).