Reconfigurable Intelligent Surface Beam Correspondence
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Solution Overview
Problem
Reconfigurable Intelligent Surfaces (RIS) face challenges in maintaining beam correspondence during two-way redirection scenarios, where the same configuration may not effectively redirect signals in both directions due to sensitivity to frequency, incident angle, and polarization, leading to inefficiencies in wireless communication.
Innovation Solution
The method involves determining beam correspondence by analyzing factors such as frequency resources, angle of arrival and departure, and RIS type, and then reconfiguring the RIS to compensate for lack of correspondence through techniques like partitioning the surface into multiple portions or using time division multiplexing to ensure proper signal redirection in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RIS is configured to redirect a signal from a first node to a second node using a single configuration, then the signal redirection in one direction is achieved, but the signal redirection in the opposite direction fails due to lack of beam correspondence
Solution Approach 1:
The RIS surface is divided into multiple independent portions or panels, each capable of being configured separately to redirect signals in specific directions. This segmentation allows different portions to handle different communication directions independently, resolving the beam correspondence issue by enabling each segment to be optimized for its specific redirection task.
Solution Approach 2:
The RIS configuration is made dynamic by allowing independent control and reconfiguration of different RIS portions based on the communication direction requirements. The system can switch between different configuration states to accommodate bidirectional signal redirection, transforming the static single-configuration limitation into a dynamic multi-state system.
2Measurement precision
If the RIS configuration is optimized for one communication direction, then beam alignment is achieved in that direction, but the same configuration fails to provide proper beam alignment in the opposite direction
Solution Approach 1:
Different portions of the RIS are assigned different local configurations optimized for their specific directional requirements. Each RIS portion has its own phase shift and amplitude settings tailored to its local redirection task, allowing high beam alignment accuracy in each direction without requiring a single universal configuration.
Solution Approach 2:
The system changes the configuration parameters (phase shifts, amplitudes, activation states) of different RIS portions based on the required communication direction. By dynamically adjusting these parameters, the system achieves proper beam alignment for each direction while managing configuration complexity through parameter-based control.
3Device complexity
If a single RIS configuration is used for both uplink and downlink communications, then device complexity is reduced, but communication reliability deteriorates due to inability to maintain beam correspondence in both directions
Solution Approach 1:
The RIS is segmented into multiple independently controllable portions, each handling specific communication directions. This segmentation allows the system to maintain multiple directional configurations simultaneously, improving bidirectional communication reliability while keeping each individual portion's configuration relatively simple.
Solution Approach 2:
The RIS system achieves multi-functionality by enabling different portions to serve different communication directions (uplink, downlink, sidelink). This universal design allows a single RIS device to handle multiple communication scenarios reliably without requiring overly complex configuration management, as each portion performs a specialized function.
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
This approach improves the throughput and reliability of uplink and downlink communications by ensuring reciprocal channel estimation and accurate beam alignment, even when initial configurations fail to maintain beam correspondence, thereby enhancing wireless communication efficiency.
Implementation Method 1
A reconfigurable intelligent surface (RIS) consists of an array of elements that can change the phase (and also amplitude, polarization, or even the frequency) of the incident wave/signal
Implementation Method 2
the RIS elements can be configured to provide desired phase-shifts for the incident-waves from the transmitter to be redirected to a desired direction towards the receiver
Data Source
AI summary
Aspects of the present disclosure provide methods and devices that facilitate two-way redirection via a reconfigurable intelligent surface (RIS) when beam correspondence does not hold. A first embodiment includes using a wide-beam redirection via RIS in which the RIS is configured to redirect the beam incident on the RIS in either direction such that the redirected beam can encompass the deviation of the redirected direction and still reach the destination. A second embodiment includes partitioning the RIS, or using multiple different RISs, where each part, or different RIS, is configured for each direction of communication. A third embodiment includes using time division-duplexing (TDD) such that the RIS is configured to transmit in one direction at a time.