Enhancing Urban Mobile Communications with Dynamic 3D Beam Tracking: A 2-Bit Phase-Quantized Adaptive RIS Approach

The imperative to secure stable data transmission for mobile users within the heart of urban zones stands as a pivotal element in the evolution of future communication infrastructures. Utilizing the adaptable beamforming prowess of Reconfigurable Intelligent Surfaces (RISs) presents a viable strategy to aid mobile users in sustaining consistent beam tracking amidst the complex urban milieu. This study delves into the dynamic beamforming potential of RIS to facilitate real-time tracking and communication across convoluted wireless landscapes. In pursuit of refined spot beamforming capabilities under near-field scenarios, this work unveils an innovative 2bit RIS unit design approach, engineered to establish stable and adjustable phase shifts whilst minimizing amplitude loss. A tangible RIS experimental framework is devised, drawing from numerical analyses and comprehensive wave simulations. This framework enables each RIS unit to autonomously toggle between states, thereby not only governing cone beams but also materializing sophisticated structured beams, such as 3D spot beams, thus augmenting the versatility of communication designs. To augment the RIS's beam tracking efficiency, an effective RIS management protocol alongside a spot beam scanning algorithm tailored for mobile users is introduced. Subsequent extensive simulations and empirical investigations, corroborate the prompt and adaptable beamforming proficiency of the proposed RIS prototype within demanding wireless contexts. The outcomes of this research significantly enrich the comprehension and application of RIS technology in the realm of forthcoming communication frameworks.