Dynamic Scattering Arrays for Simultaneous Electromagnetic Processing and Radiation in Holographic MIMO Systems

TL;DR

The paper addresses scalability and latency challenges in holographic MIMO by shifting processing into the EM domain using Dynamic Scattering Arrays (DSAs). It develops a Hertzian-dipole-based analytical model of DSAs, and an alternating-optimization framework to jointly tune the EM configuration and the digital precoder to approximate a desired end-to-end channel. Through three use cases—beamforming with a single RF chain, multi-user MISO, and multi-layer MIMO—the work demonstrates that DSAs can achieve high gains, superdirectivity, and near-ideal diagonalization with far fewer RF chains than conventional systems. The results suggest DSAs as a promising ESIT-enabled approach for sustainable, low-latency holographic MIMO, while also outlining practical challenges in reconfigurable scatterer design and integration.

Abstract

To meet the stringent requirements of next-generation wireless networks, multiple-input multiple-output (MIMO) technology is expected to become massive and pervasive. Unfortunately, this could pose scalability issues in terms of complexity, power consumption, cost, and processing latency. Therefore, novel technologies and design approaches, such as the recently introduced holographic MIMO paradigm, must be investigated to make future networks sustainable. In this context, we propose the concept of a dynamic scattering array (DSA) as a versatile 3D structure capable of performing joint wave-based computing and radiation by moving the processing from the digital domain to the electromagnetic (EM) domain. We provide a general analytical framework for modeling DSAs, introduce specific design algorithms, and apply them to various use cases. The examples presented in the numerical results demonstrate the potential of DSAs to further reduce complexity and the number of radiofrequency (RF) chains in holographic MIMO systems while achieving enhanced EM wave processing and radiation flexibility for tasks such as beamforming and single- and multi-user MIMO.

Figures (9)

• Figure 1: Principle scheme of a dynamic scattering array.
• Figure 2: Use case 1: Single RF chain DSA for high gain beamforming.
• Figure 3: Use case 2: Multi-user downlink MISO with a DSA.
• Figure 4: Use case 3: Multi-layer MIMO with the DSA acting as an holographic precoder.
• Figure 5: Radiation diagram of a disk-shape DSA ($L_{\text{R}}=1$) with $\Delta_L$ and $L=5$.