Holographic MIMO Communications Exploiting the Orbital Angular Momentum

This study delves into the potential of harnessing the orbital angular momentum (OAM)
property of electromagnetic waves in near-field and line-of-sight scenarios by utilizing large intelligent
surfaces, in the context of holographic multiple-input multiple-output (MIMO) communications. The
paper starts by characterizing OAM-based communications and investigating the connection between
OAM-carrying waves and optimum communication modes recently analyzed for communicating with
smart surfaces. Subsequently, it proposes implementable strategies for generating and detecting
OAM based communication signals using intelligent surfaces and optimization methods that leverage focusing
techniques. Then, the performance of these strategies is quantitatively evaluated through simulations. The
numerical results show that OAM waves while constituting a viable and more practical alternative to
optimum communication modes are sub-optimal in terms of achievable capacity.