Reconfigurable Intelligent Surface Assisted Communications Using Dynamic Rotations

In this paper, we propose a rotatable reconfigurable intelligent surface (RIS) assisted system to enhance the transmission quality of wireless communications. The RIS is able to rotate for maximizing the cascaded channel gain dynamically. In particular, we first introduce a continuous-time propagation model for the rotatable RIS-aided communication system. Then, a rotation angle optimization problem is formulated and solved, which boosts the channel gain of the cascaded link. Besides, we derive the expression of the spectral efficiency for the proposed system. Numerical evaluations reveal that the dynamic rotation strategy can not only enhance spectral efficiency and reduce delay spread but is still effective when rotation errors exist.