CSI Codebook Feedback Using Sparse Non-Zero Coefficients
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently utilizing channel state information (CSI) codebooks, particularly in 5G/NR systems, which require improved methods for measuring and reporting CSI to enhance beamforming and capacity in high-frequency bands.
Innovation Solution
A user equipment (UE) and base station (BS) configuration that includes a CSI codebook with spatial-domain and frequency-domain basis components, along with coefficient components, allowing for the determination and reporting of non-zero coefficients based on CSI-RS ports, optimizing CSI measurement and reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full CSI codebook with all coefficients is reported, then measurement precision is improved, but loss of information increases due to reporting overhead
Solution Approach 1:
The patent extracts and reports only the non-zero coefficients from the CSI codebook rather than reporting all coefficients. By identifying and reporting only the K1 non-zero coefficients out of the total L×M coefficients, the system reduces reporting overhead while preserving the essential channel state information needed for accurate beamforming and precoding.
Solution Approach 2:
The patent applies local quality by differentiating between zero and non-zero coefficients in the CSI codebook. Instead of treating all coefficients uniformly, the system identifies specific locations where non-zero coefficients occur and reports only those, allocating reporting resources locally to where they are most needed rather than uniformly across all coefficient positions.
2Reliability
If all CSI coefficients are reported, then reliability is improved, but device complexity increases due to processing requirements
Solution Approach 1:
The user equipment extracts only the necessary non-zero coefficient information from the full CSI codebook for reporting to the base station. This extraction process reduces the amount of data that needs to be processed, formatted, and transmitted, thereby reducing device complexity while maintaining the reliability needed for accurate channel state representation.
Solution Approach 2:
The patent applies partial action by reporting only the essential K1 non-zero coefficients rather than all L×M coefficients. This partial reporting approach provides sufficient information for reliable CSI feedback while significantly reducing the processing burden on user equipment compared to reporting the complete coefficient set.
3Productivity
If CSI reporting is performed frequently, then productivity is improved, but loss of time increases due to reporting overhead
Solution Approach 1:
By extracting and reporting only the non-zero coefficients rather than the complete CSI codebook, the patent reduces the time required for each CSI reporting instance. This enables more frequent CSI feedback updates without proportionally increasing time overhead, thereby improving overall CSI feedback efficiency and allowing the system to track channel variations more effectively.
Data Source
AI summary
Apparatuses and methods for channel state information (CSI) codebook. A method for operating a user equipment (UE) includes receiving a configuration about a CSI report. The configuration includes information about N>1 groups of CSI reference signal (CSI-RS) ports and a codebook. The codebook includes a spatial-domain (SD) basis component, a frequency-domain (FD) basis component, and a coefficient component. The SD basis component includes Lr basis vectors for each group r=1, . . . , N. The FD basis component includes Mv basis vectors. The coefficient component includes coefficients associated with (SD, FD) basis vector pairs. The method further includes, based on the configuration, measuring the N groups of CSI-RS ports and determining the SD basis component, the FD basis component, and the coefficient component such that K1 coefficients are non-zero and remaining coefficients are zero, whereK1≤∑ r=1N( 2LrMv).The method further includes transmitting the CSI report including an indicator indicating locations of non-zero coefficients.