Type-II CSI Reporting with Parameter Selection to Cut Feedback Overhead
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Solution Overview
Problem
The existing 3GPP NR Release 16 Type-II CSI codebook faces high system complexity and resource loss due to large PMI feedback bits and CSI-RS ports, leading to inefficiencies in wireless communication systems.
Innovation Solution
Implement a reciprocity-based Type-II CSI codebook with UE-assisted parameter combination selection, utilizing DFT-based CSI compression in the spatial and frequency domains to reduce PMI feedback bits and CSI-RS ports, and introduce a flexible CSI feedback reporting structure adaptable to varying UL-DL channel reciprocity strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the NR Rel-16 Type-II codebook is used with detailed CSI report, then the channel estimation accuracy is improved, but the PMI feedback bits and CSI-RS ports become very large leading to high system complexity
Solution Approach 1:
The patent segments the CSI feedback by separating the codebook selection information (RI, PMI) from the channel quality information (CQI). The codebook is divided into multiple subsets based on different channel conditions, allowing the UE to report only the necessary subset information rather than all possible codebook entries. This segmentation reduces the feedback overhead while maintaining estimation accuracy.
Solution Approach 2:
The patent extracts and removes redundant information from the CSI feedback. By using network-side assistance to determine the appropriate codebook subset and by extracting only the essential parameters (RI, PMI for selected subset, CQI), the patent eliminates unnecessary feedback bits that would increase system complexity without providing additional channel estimation value.
2Measurement precision
If the number of CSI-RS ports is increased to enable accurate channel estimation, then the measurement precision is improved, but the resource loss over reference signaling increases
Solution Approach 1:
The patent applies partial action by configuring the UE to use a subset of CSI-RS ports rather than all available ports for channel estimation. The network configures the UE with a codebook subset that corresponds to a reduced set of reference signal ports, allowing accurate estimation for the intended communication scenario while reducing the total number of CSI-RS ports that need to be transmitted and processed.
3Device complexity
If the PMI feedback bits are reduced to lower system complexity, then the device complexity is reduced, but the channel state information completeness is compromised
Solution Approach 1:
The patent applies local quality by providing different levels of detail for different parts of the CSI feedback. The codebook subset selection provides coarse-grained information about the overall channel conditions, while the selected PMI and CQI provide fine-grained information for the specific subset. This local differentiation allows the system to maintain information completeness for the actual communication scenario while reducing overall feedback complexity.
Data Source
AI summary
Apparatuses, methods, and systems are disclosed for reporting a UE-selected parameter combination for reciprocity-based Type-II CSI codebook. One apparatus includes a processor and a transceiver that receives a CSI reporting configuration from a mobile communication network, the reporting configuration containing a codebook configuration. The processor identifies a set of antenna ports based on a received set of CSI reference signals and generates at least one coefficient amplitude indicator and one coefficient phase indicator for each antenna port in the identified set of antenna ports. The processor selects a subset of at least one parameter combination from a set of two or more parameter combinations corresponding to the codebook configuration and sends a CSI report to the mobile communication network, the CSI report indicating the selected parameter combination.