Performance analysis of metasurface-based spatial multimode transmission for 6G wireless communications

In 6th generation wireless communication technology, it is important to utilize space resources efficiently. Recently, holographic multiple-input multiple-output (HMIMO) and meta-surface technology have attracted attention as technologies that maximize space utilization for 6G mobile communications. However, studies on HMIMO communications are still in an initial stage and its fundamental limits are yet to be unveiled. It is well known that the Fourier transform relationship can be obtained using a lens in the optical field, but research to apply it to the mobile communication field is in the early stages. In this paper, we show that the Fourier transform relationship between signals can be obtained when two metasurfaces are aligned or unaligned, and analyze the transmission and reception power, and the maximum number of spatial multimodes that can be transmitted. In addition, to reduce transmission complexity, we propose a spatial multimode transmission system using three metasurfaces and analyze signal characteristics on the meta-surfaces. In numerical results, we provide the performance of spatial multimode transmission in case of using rectangular and Gaussian signals.