Symbol Error Rate Analysis of Single Versus Multi-RIS Assisted Wireless Communication System

Reconfigurable Intelligent Surfaces (RISs) possess the capability to enhance the efficiency of wireless communication systems when direct Line-of-Sight (LoS) between transceivers is obstructed.While employing multiple RIS units proves advanta-geous for communication enhancement, the escalating complexity with an increased number of RISs necessitates finding an optimal number of RISs. To address this, we investigate the Symbol Error Rate (SER) in centralized single RIS and distributed multi-RIS configurations with two and four RIS units. The analysis employs Moment Generating Function (MGF)-based SER assessments, considering Rayleigh fading channels. The evaluation is performed against a single RIS system, where the RIS is positioned midway between transceivers. The comparative SER evaluation, ensuring an equal number of RIS elements across all systems, indicates that both double and quadruple RIS configurations outperform the single RIS system and using two RIS units shown significant improvement in performance, suggesting sufficiency without the need for a larger number of RIS units.