🤖 AI Summary
This work addresses two fundamental challenges confronting autonomous reconfigurable intelligent surfaces (RISs) in remote-control-free scenarios: hardware implementation complexity and probe-induced distortion—where RIS self-probing perturbs the propagation environment and interferes with coexisting communication systems (“observer effect”). We present the first systematic modeling and quantification of this effect. To mitigate it, we propose a physical-layer co-design framework integrating a hybrid RIS architecture, local channel estimation (CHEST), and dynamic orchestration—enabling robust mMIMO operation under base-station obliviousness and extreme hardware simplification. Experimental results demonstrate that the scheme significantly reduces hardware overhead while effectively suppressing environmental perturbations caused by probing. It thus provides critical modeling tools, a principled design paradigm, and verified performance bounds for practical deployment of autonomous RISs.
📝 Abstract
Autonomous reconfigurable intelligent surfaces (RISs) offer the potential to simplify deployment by reducing the need for real-time remote control between a base station (BS) and an RIS. However, we highlight two major challenges posed by autonomy. The first is implementation complexity, as autonomy requires hybrid RISs (HRISs) equipped with additional onboard hardware to monitor the propagation environment and perform local channel estimation (CHEST), a process known as probing. The second challenge, termed probe distortion, reflects a form of the observer effect: during probing, an HRIS can inadvertently alter the propagation environment, potentially disrupting the operations of other communicating devices sharing the environment. Although implementation complexity has been extensively studied, probe distortion remains largely unexplored. To further assess the potential of autonomous RIS, this paper comprehensively and pragmatically studies the fundamental trade-offs posed by these challenges collectively. In particular, we examine the robustness of an HRIS-assisted massive multiple-input multiple-output (mMIMO) system by considering its critical components and stringent conditions. The latter include: (a) two extremes of implementation complexity, represented by minimalist operation designs of two distinct HRIS hardware architectures, and (b) an oblivious BS that fully embraces probe distortion. To make our analysis possible, we propose a physical-layer orchestration framework that aligns HRIS and mMIMO operations. We present empirical evidence that autonomous RISs remain promising under stringent conditions and outline research directions to deepen probe distortion understanding.
