CSI Codebook Structure Using DFT Basis for Time-Domain Precoding
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Solution Overview
Problem
Existing wireless communication systems, particularly in 3GPP NR, have not adequately exploited the channel time domain properties for CSI reporting, leading to inefficiencies in precoding and increased signaling overhead, especially in multi-TRP scenarios.
Innovation Solution
Introduce a new codebook structure that exploits channel time domain properties by using discrete Fourier transform (DFT) sequences for CSI enhancement, allowing for CSI reporting that includes time and/or Doppler domain basis, with optional oversampling and subset selection mechanisms to reduce overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing codebook structures are used for CSI reporting, then system compatibility is maintained, but CSI reporting accuracy is insufficient and time domain properties are not exploited
Solution Approach 1:
The codebook is segmented into frequency domain basis vectors and time domain basis vectors, allowing independent optimization of each component. This segmentation enables the system to exploit time domain properties through dedicated time basis vectors while maintaining compatibility through established frequency domain structures.
Solution Approach 2:
The patent extends the traditional frequency-domain codebook structure by adding a time domain dimension. This is achieved by incorporating time basis vectors that capture temporal correlations, transforming the codebook from a single-domain structure to a multi-dimensional structure that exploits both frequency and time domain properties.
2Manufacturing precision
If detailed CSI reporting is implemented, then precoding accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent changes the parameter representation by using basis vector indices instead of full channel matrices. By reporting which time and frequency basis vectors are active rather than reporting complete channel state information, the system achieves high precoding accuracy with reduced signaling overhead.
Solution Approach 2:
Instead of reporting complete channel matrices, the system reports compressed representations using basis vector indices. This copying approach captures the essential channel characteristics through selected basis vectors while significantly reducing the amount of signaling data required.
3Adaptability or versatility
If time domain basis vectors are added to the codebook, then time domain correlations are exploited, but codebook complexity increases
Solution Approach 1:
The codebook is segmented into frequency domain basis vectors and time domain basis vectors, allowing independent optimization of each component. This segmentation enables the system to exploit time domain properties through dedicated time basis vectors while maintaining compatibility through established frequency domain structures.
Solution Approach 2:
The extended codebook structure serves multiple functions: it maintains backward compatibility with existing frequency-domain codebooks while simultaneously enabling time domain correlation exploitation. The unified codebook framework can adapt to different deployment scenarios, providing universal applicability across various system configurations.
4Measurement precision
If full CSI-RS bursts are transmitted for time domain measurement, then measurement accuracy is improved, but resource consumption increases
Solution Approach 1:
The patent changes the measurement approach by using compressed basis vector representations instead of full channel matrices. This allows accurate channel characterization through reduced measurement data, decreasing the energy required for CSI-RS transmission while maintaining measurement accuracy.
Solution Approach 2:
Instead of transmitting complete CSI-RS bursts for full channel measurement, the system uses partial measurements that capture the essential channel characteristics through selected time and frequency basis vectors. This partial action approach achieves sufficient measurement accuracy with reduced resource consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances CSI reporting accuracy and reduces signaling overhead by leveraging time domain correlations, improving precoding in multi-TRP environments and supporting coherent joint transmission.
Implementation Method 1
Introduce a new codebook structure that exploits channel time domain properties by using discrete Fourier transform (DFT) sequences for CSI enhancement
Data Source
AI summary
Apparatus and methods are provided for codebook configuration including enhancements for channel time domain properties. A user equipment (UE) receives a channel measurement resource (CMR) configuration to support channel state information (CSI) reporting based on channel time domain properties. The CMR configuration corresponds to a burst of N time domain equally spaced CMR. The UE measures, based on the CMR configuration, CSI references signals (CSI-RSs) from one or more transmission and reception point (TRP). The UE determines, based on measurements of the CSI-RSs, multiple time domain equally spaced precoding matrix indicator (PMI) matrices. The UE encodes the multiple time domain equally spaced PMI matrices using N orthogonal discrete Fourier transform (DFT) sequences as time or Doppler domain basis, where each of the N orthogonal DFT sequences includes N entries. The UE reports the multiple time domain equally spaced PMI matrices that are encoded using time or Doppler domain basis.