Reconfigurable Intelligent Surface Prism Effect Compensation
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently directing and compensating for the prism-like effect of Reconfigurable Intelligent Surfaces (RIS) in high-frequency bands, leading to interference and multipath fading issues due to the redirection of different frequency components in various directions.
Innovation Solution
The method involves configuring RIS elements with different bias voltages to redirect specific frequency components in desired directions, using configuration information to manage channel estimation and data transmission, and compensating for multipath fading by configuring the RIS to reduce deviation from the main desired direction or using equalization methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If RIS redirects different frequency components in different directions to achieve beamforming, then signal directionality is improved, but multipath fading and interference occur due to the prism-like effect
Solution Approach 1:
The patent applies parameter changes by adjusting the phase shift values of different RIS elements based on frequency-specific channel state information. The base station determines frequency-dependent phase shifts for different frequency components and configures the RIS accordingly, allowing each frequency component to be redirected in the desired direction while compensating for the prism-like effect. This resolves the contradiction by dynamically changing the RIS configuration parameters to maintain signal directionality while eliminating multipath fading and interference.
2Measurement precision
If wideband reference signals are used for channel estimation, then channel information accuracy is improved, but frequency components are redirected in different directions causing estimation errors
Solution Approach 1:
The patent applies segmentation by dividing the wideband reference signal into multiple frequency components and processing each component separately. The base station determines channel state information for each frequency component individually and generates separate phase shift configurations for each component. This segmentation approach allows accurate channel estimation for each frequency while compensating for the prism-like effect, resolving the contradiction between wideband accuracy and frequency component separation.
Solution Approach 2:
The patent uses parameter changes by configuring the RIS with frequency-dependent phase shift values. The base station determines optimal phase shifts for each frequency component based on measured channel state information and updates the RIS configuration accordingly. This dynamic parameter adjustment enables the RIS to correctly redirect each frequency component while maintaining accurate channel estimation across the entire bandwidth.
3Adaptability or versatility
If multiple reference signals at different frequencies are transmitted, then channel estimation coverage is improved, but overhead increases due to multiple transmissions
Solution Approach 1:
The patent applies merging by combining multiple frequency-specific reference signal transmissions into a single wideband reference signal transmission. The base station transmits one wideband reference signal that covers multiple frequencies, measures the channel state for each frequency component, and then configures the RIS with frequency-dependent phase shifts. This merging approach maintains comprehensive channel estimation coverage while significantly reducing overhead compared to transmitting separate reference signals for each frequency.
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 enhances channel estimation accuracy and data transmission efficiency by minimizing interference and multipath fading effects, allowing for improved signal strength and reduced overhead in RIS-based communication systems.
Implementation Method 1
compensating for the prism-like effect of the RIS by configuring the RIS to reduce a deviation from a main desired direction
Implementation Method 2
transmit a reference signal that is redirected by the RIS based on second configuration information that configures the RIS to redirect different frequency components of the reference signal in different directions
Implementation Method 3
compensating for multipath fading by configuring the RIS to reduce deviation from the main desired direction or using equalization methods
Data Source
AI summary
Aspects of the present disclosure take advantage of a prism-like effect that occurs in a Reconfigurable Intelligent Surface (RIS), where the RIS reflects incident signals of different frequencies in different directions. for determining characteristics of a channel between a transmitter and a receiver wherein the channel includes the RIS. In particular, this may include estimating an angle of arrival (AoA) to the RIS in uplink transmission or the angle of departure (AoD) from the RIS in downlink transmission. Aspects of the present disclosure also provide solutions to compensate the prism effect for wideband transmission, especially at high frequencies (e.g. mmWave and THz).