FDD Coherent JT CSI Reporting with Shared Codebook Compression
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Solution Overview
Problem
Existing CSI reporting frameworks are inefficient for joint transmission scenarios with multiple TRPs, leading to high feedback overhead due to the need for precise precoding and co-phasing information across multiple transmission/reception points.
Innovation Solution
Implementing a wireless transmit/receive unit (WTRU) that reduces feedback overhead by reporting CSI for multiple TRPs, including coherent and non-coherent joint transmission scenarios, through optimized PMI and co-phasing information, and enhanced compression techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CSI reporting is performed for multiple TRPs with precise precoding and co-phasing information, then channel state information accuracy is improved, but feedback overhead increases
Solution Approach 1:
The patent segments the codebook indices into two distinct types: shared codebook indices that are common across multiple TRPs and non-shared codebook indices that are specific to individual TRPs. This segmentation allows the WTRU to report only the necessary differential information rather than complete independent CSI for each TRP, thereby reducing feedback overhead while maintaining accurate channel state information for multiple transmission points
Solution Approach 2:
The patent merges the reporting of shared codebook indices across multiple TRPs into a single unified report. By identifying and combining the common precoding information that applies to multiple TRPs, the system eliminates redundant feedback transmissions while preserving the accuracy needed for coherent joint transmission across the coordinated TRP set
2Manufacturing precision
If complete PMI and co-phasing information is reported for each TRP, then precoding accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent applies local quality by differentiating between shared and non-shared codebook indices based on their specific characteristics and usage patterns. Shared codebook indices are identified for TRPs that utilize common precoding structures, while non-shared indices are reported only for TRPs with unique precoding requirements. This localized differentiation ensures that precoding accuracy is maintained where needed while avoiding redundant signaling overhead where it is not required
3Measurement precision
If basis sets are reported for each coherent JT TRP independently, then channel representation accuracy is improved, but feedback overhead increases
Solution Approach 1:
The patent implements universality by enabling a single basis set report to serve multiple coherent joint transmission TRPs simultaneously. When TRPs share common channel characteristics and precoding structures, the same basis set can be universally applied across all such TRPs, eliminating the need for separate independent basis set reports for each TRP while maintaining accurate channel representation for all participating TRPs in the coherent joint transmission
Data Source
AI summary
Systems, methods, and instrumentalities are described herein for joint transmission (JT) channel state information (CSI) reporting. Joint transmission CSI may be coherent JT CSI or non-coherent JT CSI. Feedback overhead may be reduced, for example, if reporting CSI for multiple transmission/reception points (TRPs). Precoding matrix indicators (PMIs) and/or co-phasing information for TRPs in JT (e.g., coherent JT or non-coherent JT) may be reported. A wireless transmit/receive unit (WTRU) may be configured to employ operations to reduce feedback overhead and/or report PMIs and/or co-phasing information for TRPs in JT.