Flexible Intelligent Metasurface-Aided Wideband Multiuser MISO Communication Systems

Abstract

Flexible intelligent metasurface (FIM) has emerged as a promising antenna technology for next-generation wideband communications, owing to its capability of dynamic three-dimensional surface-shape morphing. Unlike a conventional rigid uniform planar array (UPA), the FIM provides an additional geometric degree of freedom that actively reshapes wireless channels. In this paper, we investigate an FIM-aided wideband multi-user multiple-input single-output (MISO) system, where the FIM is deployed at the base station to serve multiple single-antenna users via orthogonal frequency-division multiplexing (OFDM). We formulate an optimization problem to maximize the system spectral efficiency by jointly designing the FIM surface shape and the fully-digital precoding matrices, subject to transmit power and morphing range constraints. To cope with the non-convex and coupled nature of this problem, an efficient alternating optimization algorithm is proposed, which decomposes the joint design into the precoding refinement based on weighted minimum mean-square error and the surface-shape update based on projected gradient ascent. Numerical results demonstrate that the proposed FIM-based scheme achieves significant spectral efficiency improvement over the rigid UPA baseline.