RIS Virtual Array Channel Estimation Without AoA-AoD Association
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Solution Overview
Problem
Existing channel estimation methods for Reconfigurable Intelligent Surface (RIS) assisted communication systems, particularly in frequency bands above 6GHz, face challenges such as increased power requirements, computational complexity, and hardware costs due to active elements, and require separate estimation of Angle of Departure (AoD) and Angle of Arrival (AoA), necessitating additional computationally demanding steps.
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 Khatri-Rao property to estimate angles ψ and θ, eliminating the need for separate AoD and AoA estimation, and enabling efficient channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate estimation of AoD and AoA is performed, then channel estimation can be completed, but computational complexity increases and additional data association steps are required
Solution Approach 1:
The patent combines the separate AoD and AoA estimation processes into a unified joint estimation approach. By formulating the channel estimation as a single optimization problem that simultaneously estimates both angles, the method eliminates the need for separate estimation steps and subsequent data association, thereby reducing computational complexity while maintaining estimation accuracy.
Solution Approach 2:
The proposed channel estimation method serves multiple functions simultaneously: it estimates both AoD and AoA, performs data association implicitly, and provides complete channel state information. This multi-functional approach replaces what would otherwise require multiple separate processing stages, reducing overall system complexity.
2Measurement precision
If active elements are used at RIS, then channel estimation can be performed, but power requirement and hardware cost increase
Solution Approach 1:
The patent employs passive RIS elements that utilize the incident signal power to perform channel estimation without requiring additional active components or external power sources at the RIS. The passive elements reflect and modulate the signal based on their configuration, enabling channel state information acquisition while maintaining zero power consumption at the RIS side.
Solution Approach 2:
The passive RIS elements act as intermediaries that facilitate channel estimation by reflecting the transmitted signal with controlled phase shifts. These passive elements mediate between the transmitter and receiver, enabling the receiver to extract channel information without requiring active components at the RIS, thus avoiding additional power requirements.
Data Source
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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.