Compressed Channel Feedback via Basis Decomposition in MU-MIMO
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Solution Overview
Problem
Current NR CSI framework fails to provide accurate channel information feedback, especially in MU-MIMO scenarios, leading to inadequate interference management and signal performance degradation.
Innovation Solution
A method involving an apparatus that receives a reference signal from a network node, derives channel response information, decomposes it into a preferred domain, determines a linear combination coefficient representation, and reports compressed channel information to the network side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current NR CSI framework is used for channel information feedback, then the feedback process is simple, but the accuracy of channel information feedback deteriorates in MU-MIMO scenarios
Solution Approach 1:
The patent segments the channel information feedback into two parts: prior information (channel response matrix H) and post information (precoding matrix indicator PMI). The prior information is compressed using basis decomposition where the channel matrix is represented as a linear combination of selected basis matrices. This segmentation allows the network to obtain accurate channel state information while the UE only needs to feedback compressed coefficients and PMI, reducing feedback complexity.
Solution Approach 2:
The patent introduces basis matrices as an intermediary between the channel response and the feedback information. Instead of directly feedbacking the full channel matrix or traditional CSI reports, the UE decomposes the channel response into a weighted sum of basis matrices and only feedbacks the weights (linear combination coefficients) and PMI. This intermediary representation reduces feedback overhead while maintaining accuracy for interference management.
2Reliability
If traditional CSI feedback is used, then the feedback overhead is reduced, but the interference management capability deteriorates
Solution Approach 1:
The patent extracts only the essential information needed for interference management from the full channel response. By decomposing the channel matrix H into basis matrices and extracting only the linear combination coefficients and PMI, the system removes redundant information while retaining the critical components needed for accurate precoding and interference management at the network side.
Solution Approach 2:
The patent changes the parameter representation from traditional CSI parameters (CQI, PMI, RI) to a new parameter set consisting of basis decomposition coefficients and selected basis indices. This parameter transformation enables more efficient representation of channel state information, reducing feedback overhead while providing the network with sufficient information for advanced interference management techniques.
3Measurement precision
If full channel information is fed back, then the network can perform accurate precoding, but the feedback overhead increases significantly
Solution Approach 1:
Instead of feedbacking the complete channel matrix, the patent applies partial action by only feedbacking the compressed representation (linear combination coefficients and PMI). The basis decomposition allows the network to reconstruct accurate channel state information from these partial feedbacks, achieving sufficient precision for precoding without the excessive overhead of full channel matrix feedback.
Data Source
AI summary
Various solutions for channel information feedback with prior information with respect to user equipment and network apparatus in mobile communications are described. An apparatus may receive a reference signal transmitted by a network side including at least one network node. The apparatus may obtain at least one selected basis. The apparatus may derive a channel response information observed by a receiving domain of the apparatus according to the reference signal. The apparatus may decompose the channel response information into a preferred domain. The apparatus may determine a simplified linear combination coefficient representation of the channel response information in the preferred domain according to the selected basis. The apparatus May report a compressed channel information to the network side based on the simplified linear combination coefficient representation and the preferred domain.