Angular-Delay CSI Sparsity Reporting for Lower Feedback Overhead
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high overhead associated with channel state information (CSI) feedback in wireless communication systems, particularly in MU-MIMO FDD systems, necessitates efficient reduction strategies.
Innovation Solution
Leveraging channel sparsity in angular-delay or delay-Doppler domains by transforming CSI feedback and utilizing sparsity-assisted truncation or two-step CSI reporting, which includes configuring non-zero coefficients and threshold values for truncation, and employing time correlation to reduce feedback overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full CSI feedback is transmitted, then channel state information accuracy is improved, but feedback overhead increases
Solution Approach 1:
The patent extracts only the essential CSI components by identifying and reporting non-zero coefficients in the angular-delay domain. Instead of transmitting full CSI matrices, the system extracts and reports only significant channel parameters (non-zero coefficients and their corresponding angles and delays), thereby reducing feedback overhead while preserving essential channel state information for accurate precoding.
Solution Approach 2:
The patent applies local quality by differentiating between significant and insignificant channel components. In the angular-delay domain, only locations with non-zero coefficients (significant path components) are reported, while zero or near-zero coefficients are omitted. This selective reporting strategy maintains accuracy for important channel characteristics while eliminating redundant information transmission.
2Quantity of substance
If sparsity-assisted truncation is applied, then feedback overhead is reduced, but CSI reporting complexity increases
Solution Approach 1:
The patent performs preliminary transformation of CSI from the spatial domain to the angular-delay domain before truncation. By pre-transforming the CSI using discrete Fourier transform (DFT) matrices to obtain the angular-delay representation, the system identifies non-zero coefficients in advance, allowing for efficient truncation decisions to be made before feedback transmission, thus reducing overhead while managing complexity through structured preprocessing.
Solution Approach 2:
The patent changes the representation parameters of CSI by transforming from spatial domain coordinates to angular-delay domain coordinates. This parameter transformation reveals the sparse structure of the channel, enabling identification of non-zero coefficients at specific angle-delay locations. The system then reports only these significant parameters rather than complete spatial matrices, reducing feedback overhead while maintaining essential channel information.
3Productivity
If two-step CSI reporting is implemented, then feedback efficiency is improved, but system complexity increases
Solution Approach 1:
The patent segments CSI feedback into two distinct steps: first transmitting quantized channel coefficients and basic parameters, then subsequently transmitting derived precoding information and feedback. This segmentation allows the system to break down the complex feedback process into manageable stages, improving efficiency by allowing the base station to process intermediate results and provide targeted feedback requests, while managing system complexity through structured multi-phase operation.
Data Source
AI summary
Sparsity assisted channel state information (CSI) reporting or two-step CSI reporting is enabled or disabled for a user equipment. The configuration enabling/disabling sparsity assisted truncation for CSI reporting or two-step CSI reporting includes a domain for transformation of CSI for the sparsity assisted CSI reporting, and a time window for correlated channel. When the configuration enables sparsity assisted truncation for CSI reporting, a fixed number of non-zero coefficients and one or more threshold values for delay/angle or doppler for truncation are configured. When sparsity assisted truncation for CSI reporting is enabled, received the CSI reference signals are measured based on the configuration and a CSI report is transmitted indicating a specific range for which truncation occurred. When two-step CSI reporting is enabled, CSI compression corresponding to the at least one configuration and the time window is performed and CSI feedback is transmitted along with a flag.