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 relation-ship between OAM-carrying waves and communication modes established between intelligent surfaces is discussed, and practical strategies for exploiting OAM with LISs are then presented. Nu-merical 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.