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

TL;DR

This paper introduces a novel RIS-aided index modulation scheme utilizing K-means clustering to optimize reflection patterns, significantly enhancing error performance in wireless communication systems.

Contribution

It proposes a new RIS-based index modulation method with K-means optimized reflection constellation and a Gray coding scheme, improving error rates over traditional approaches.

Findings

K-means optimized reflection constellation improves BER performance.

The proposed scheme outperforms conventional RIS-based IM methods.

Analytical BER bounds closely match simulation results.

Abstract

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, we study an RIS-aided multiple-input single-output (MISO) system, in which the information bits are conveyed by reflection patterns of RIS rather than the conventional amplitude-phase constellation. Furthermore, the K-means algorithm is employed to optimize the reflection constellation to improve the error performance. Also, we propose a generalized Gray coding method for mapping information bits to an appropriate reflection constellation and analytically evaluate the error performance of the proposed scheme by deriving a tight upper bound of the average bit error rate (BER). Finally, numerical results verify the accuracy of our theoretical analysis as well as the substantially improved BER performance of the proposed RIS-based IM transmission scheme.