Three-Component CSI Codebook Reporting with Selective UCI Omission
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Solution Overview
Problem
The existing 3GPP Rel. 15 three-component CSI reporting scheme faces high feedback overhead and requires new UCI omission rules due to the absence of subband-based PMIs, which cannot be decomposed, and recalculation of CSI matrices for omission would consume additional UE resources.
Innovation Solution
Implement UCI omission schemes by dropping portions of amplitude and phase information of non-zero combining coefficients and bitmaps associated with dropped coefficients, segmenting CSI reports into subgroups with priority levels, and ensuring recalculation of CSI matrices is not required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If UCI omission is implemented by dropping portions of CSI reports, then feedback overhead is reduced, but recalculation of CSI matrices would consume additional UE resources
Solution Approach 1:
The CSI report is segmented into multiple parts: Part 1 contains RI and first PMI (wideband spatial parameters) while Part 2 contains second PMI (subband amplitude and phase information). This segmentation allows selective omission of Part 2 when resources are limited, while preserving the essential wideband spatial parameters in Part 1 that do not require recalculation.
Solution Approach 2:
The patent extracts and separates the subband-specific amplitude and phase information (second PMI) from the wideband spatial parameters (first PMI and RI). By taking out the frequency-dependent components into a separate reportable part, the system enables omission of these extracted components without affecting the fundamental spatial precoding information, thus reducing feedback overhead without requiring recalculation of the wideband CSI matrices.
2Measurement precision
If three-component codebook-based CSI reporting is used, then CSI accuracy is improved, but feedback overhead increases due to absence of subband-based PMIs
Solution Approach 1:
The patent introduces a dimensional separation between wideband spatial parameters (first PMI with oversampling factors O1, O2) and subband frequency parameters (second PMI with amplitude and phase). This dimensional change allows the system to maintain accurate three-component codebook-based CSI representation while managing feedback overhead by selectively reporting only essential components based on resource availability.
Solution Approach 2:
The patent changes the parameter representation by separating amplitude and phase information into a distinct second PMI from the spatial beam parameters in the first PMI. This parameter change enables flexible feedback strategies where amplitude and phase can be omitted or quantized with lower precision when resources are constrained, while preserving the accurate spatial codebook structure for MIMO precoding.
3Adaptability or versatility
If new UCI omission rules are created for three-component codebook, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining the two-part CSI report structure with clear roles for each part before omission decisions are made. Part 1 is designed to contain essential wideband spatial parameters that serve as a foundation, while Part 2 contains optional subband refinements. This preliminary structuring simplifies omission rules by establishing a hierarchical dependency where Part 2 can be selectively dropped without affecting the interpretability of Part 1.
Solution Approach 2:
The patent implements partial action by allowing the UE to report only Part 1 of the CSI report when uplink resources are insufficient, rather than requiring complete CSI reports or complex recalculation. This partial reporting strategy provides adaptability by adjusting the level of CSI detail based on resource availability, while the simplified omission rule (report Part 1 only) reduces device complexity compared to managing three-component codebook omissions.
Data Source
AI summary
A method performed by a UE for providing CSI feedback in the form of CSI reports in a wireless communication system includes receiving, from a gNB, higher layer configurations of one or more downlink reference signals, and CSI report configurations associated with the downlink reference signal configurations, and a radio signal including the downlink reference signals according to the one or more downlink reference signal configurations, the downlink reference signals provided over a configured number of frequency domain resources, time domain resources and one or more ports; determining, for each CSI report, a precoding matrix based on the downlink reference signals and two codebooks, and one or more non-zero combining coefficients for complex combining of one or more spatial domain and delay domain basis vectors; and reporting to the network node the CSI reports for the CSI report configurations.