Novel Multiple RIS-Assisted Communications for 6G Networks

As an emerging technique, reconfigurable intelligent surface (RIS) has recently received extensive attention and can be considered as a key enabling technology for future sixth generation (6G) wireless communication networks. In this letter, we propose a novel multiple RIS-assisted single-input-single-output (SISO) wireless communication system working in a domino pattern when obscuration is severe. The upper bound of the ergodic capacity and the outage probability for the proposed system are analyzed and the corresponding closed-form expressions are provided under Nakagami-
$m$
fading channels. The general multiple RIS-assisted systems including two RISs and
$K$
RISs are analyzed. Numerical results indicate that the number of RISs, the number of RIS elements, and the communication environment can significantly affect the upper bound of the ergodic capacity and the outage probability performance of the proposed system. The feasibility of the proposed system and the accuracy of the upper bound of the ergodic capacity and the outage probability are also verified by the numerical results.