OAM-based Holographic MIMO using Large Intelligent Surfaces

This paper addresses the exploitation of the orbital angular momentum (OAM) property of the electromagnetic waves with large intelligent surfaces (LISs) in near-field and line-of-sight propagation conditions for holographic multiple-input multiple-output (MIMO) communications. The relationship between OAM-carrying waves and communication modes established between intelligent surfaces is discussed, and practical strategies for exploiting OAM with LISs are then presented. Numerical results characterize the effectiveness of OAM compared to alternative strategies, though highlighting that OAM-based techniques constitute a particular choice of basis set that is sub-optimum with respect to the basis sets corresponding to optimal communication modes, albeit ensuring lower complexity.