RIS Channel Estimation With Joint AoA/AoD Virtual Array Processing
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Solution Overview
Problem
Existing channel estimation methods for Reconfigurable Intelligent Surface (RIS) assisted communication systems, particularly in frequency bands above 6 GHz, face challenges such as increased power requirements, computational complexity, hardware costs, and the need for separate estimation of Angle of Departure (AoD) and Angle of Arrival (AoA), which are computationally demanding.
Innovation Solution
A method involving the joint visualization of RIS elements and multi-antenna receiver array elements as a RIS-Single Input Multiple Output (SIMO) virtual array, using singular value decomposition and eigen vector computation to estimate angles ψ and θ, eliminating the need for separate AoD and AoA estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate estimation of Angle of Departure (AoD) and Angle of Arrival (AoA) is performed, then channel estimation can be completed, but computational complexity increases significantly
Solution Approach 1:
The patent combines separate AoD and AoA estimation processes into a unified channel estimation approach. By treating the RIS-assisted channel as a cascaded channel estimation problem and using joint signal processing techniques, the system estimates both angles simultaneously rather than separately, thereby reducing computational complexity while maintaining estimation accuracy.
Solution Approach 2:
The patent introduces the RIS channel as an intermediary element in the estimation process. By utilizing the RIS-assisted signal path and the known RIS configuration, the system creates an intermediate estimation step that enables more efficient joint angle estimation, avoiding the need for separate complex estimations of AoD and AoA.
2Measurement precision
If semi-passive RIS with active elements is used, then channel estimation can be performed, but power requirement and hardware cost increase
Solution Approach 1:
The patent employs a fully passive RIS configuration where the RIS elements themselves perform the channel estimation function without requiring active electronic components. The passive RIS reflects and modulates the signal based on its configurable phase shifts, enabling channel estimation through signal processing at the transmitter and receiver ends alone, thereby eliminating the need for power-consuming active elements at the RIS.
Solution Approach 2:
The patent replaces expensive and power-consuming active RIS elements with simple, passive, and cost-effective reflective elements. The passive RIS configuration uses basic metamaterial elements that can be configured through passive phase shifters, significantly reducing hardware cost and power requirements while maintaining the ability to perform channel estimation through intelligent signal reflection.
3Use of energy by moving object
If passive RIS is used with MMSE-based CE approach, then power consumption is reduced, but computational complexity increases
Solution Approach 1:
The patent segments the channel estimation problem into manageable parts by exploiting the structured nature of the RIS-assisted cascaded channel. By decomposing the estimation process into steps that leverage the known RIS configuration and the statistical properties of the channel, the system reduces the overall computational burden compared to applying full MMSE estimation to the entire cascaded channel at once.
Solution Approach 2:
The patent changes the estimation approach by utilizing the specific parameters and structure of the RIS-assisted channel. By incorporating prior knowledge about the RIS configuration, the signal model, and channel statistics into the estimation process, the system adapts the estimation parameters to exploit the system's unique characteristics, thereby reducing computational complexity while maintaining accuracy.
Data Source
AI summary
Existing approaches for channel estimation in Reconfigurable Intelligent Surface (RIS) assisted communication systems have the disadvantage that they require separate estimation of Angle of Arrival (AoA) and Angle of Departure (AoD), requiring additional step of computationally demanding data association. Embodiments disclosed herein provide a method and system for channel estimation in RIS assisted communication systems. In this approach, the system jointly visualizes the plurality of RIS elements and the plurality of multi-antenna receiver array elements as a RIS-SIMO virtual array, thereby eliminating need to separately estimate the AoA and AoD.