Nearly-Passive RIS Unit Selection for Coherent Signal Alignment
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Solution Overview
Problem
The reliability and quality of service (QoS) of wireless communication links have traditionally been governed by the capabilities of end-nodes, such as transmitters or receivers, limiting improvements in wireless channel quality.
Innovation Solution
The use of Reconfigurable Intelligent Surfaces (RIS) to manipulate electromagnetic signals by optimizing the phase-shifts of sub-wavelength unit cells to enhance signal quality at the receiver, leveraging technologies like massive MIMO and beamforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Reconfigurable Intelligent Surface (RIS) is used to manipulate electromagnetic signals, then wireless channel quality, reliability, and throughput are enhanced, but device complexity and control difficulty increase
Solution Approach 1:
The patent introduces a gNB (base station) as an intermediary that centrally controls the RIS device. The gNB determines the RIS configuration based on channel state information and transmission requirements, then configures the RIS accordingly. This intermediary approach allows complex RIS manipulation to be managed through a centralized controller rather than requiring distributed control across multiple nodes.
Solution Approach 2:
The patent manipulates electromagnetic wave propagation by changing the phase shift parameters of individual RIS elements. Each element's reflection coefficient phase is adjusted dynamically based on the desired beamforming pattern and channel conditions. This parameter-based control enables precise wavefront shaping to improve channel quality without requiring complex structural changes.
2Productivity
If phase-shifts of RIS unit cells are optimized using machine learning and global co-phasing techniques, then signal quality and spectrum efficiency improve, but computational complexity and processing time increase
Solution Approach 1:
The patent performs preliminary channel state information acquisition and analysis at the gNB before configuring the RIS. The gNB collects CSI from the wireless channel, pre-calculates the optimal RIS configuration using machine learning models or global co-phasing algorithms, and then applies this pre-determined configuration. This preliminary action allows the system to prepare optimization solutions in advance, reducing real-time computational burden during actual transmission.
3Measurement precision
If a large number of sub-wavelength unit cells are deployed in RIS, then phase control precision and signal quality enhancement improve, but manufacturing complexity and cost increase
Solution Approach 1:
The patent divides the RIS into multiple independently controllable unit cells, each capable of introducing a specific phase shift. These segmented elements are arranged in a grid pattern across the RIS surface. By segmenting the RIS into discrete controllable units rather than a continuous structure, the system achieves precise phase control while maintaining manufacturability through modular assembly of standardized elements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances wireless channel quality, reliability, throughput, and spectrum efficiency, particularly in 5G and emerging 6G cellular systems, by optimizing phase-shifts in RIS structures using machine learning methods and global co-phasing techniques.
Implementation Method 1
optimizing the phase-shifts of sub-wavelength unit cells to enhance signal quality at the receiver
Implementation Method 2
Reconfigurable Intelligent Surface (RIS) is a generic term used for meta-surfaces that may improve the wireless channel quality between a transmitter and a receiver by manipulating the impinging electromagnetic signals
Data Source
AI summary
Reconfigurable Intelligent Surface devices, RIS, may be used to improve receipt of radio signals received by wireless transmit-receive units, WTRUs, in a given area. In such area, WTRUs may receive radio signals directly from the transmitter, and indirectly, via reflection of the radio signals from the transmitter by the RIS device. A RIS may consist of programmable sub-wavelength sized unit cells placed in close proximity. Each unit cell behaves like a scatterer. Embodiments of a new RIS structure are described here, being based on a nearly passive reflecting platform. In a Nearly-Passive RIS structure according to embodiments, NP-RIS, each unit cell is programmed to have a constant invariable phase-shift. Embodiments of a unit cell selection method are described, to control the reflected wave by selecting a subset of unit cells whose reflection could assist coherent alignment of the reflected wave with the main direct signal at the WTRU.