Research Specifications

In high-mobility communication contexts, the rapidly fluctuating channel has a considerable effect on both the throughput and reliability of communications. Beyond diagonal reconfigurable intelligent surfaces (BD-RIS) alleviates the limitations of conventional reconfigurable intelligent surfaces (RIS) by enabling the flexible arrangement of elements, resulting in an enhancement of the maximum achievable rate. In this paper, a method is presented to design the scattering matrix for roadside BD-RIS with a flexible grouping strategy by maximizing the reflected channel gain. In the proposed method, to avoid the high computational burden, maximizing the upper bound of the channel gain is used for the design of the permutation function. Also, the scattering matrix of the classical grouping is designed by solving the optimization problem in a reference time block and is subsequently updated in non-reference blocks. Simulation results indicate that the presented approach outperforms the reference methods regarding channel gain.