Doppler-Delay Precoder Codebook for CSI Feedback
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Solution Overview
Problem
Current CSI reporting formats in wireless communication systems are inefficient, particularly in fast-fading channels, leading to high feedback overhead due to the need for frequent updates, and they fail to accurately track channel evolution over time, especially in multi-user MIMO scenarios.
Innovation Solution
A communication device and method that utilize a Doppler-delay-beam three-stage precoder matrix based on codebooks, including spatial, delay, and Doppler-frequency components, to provide CSI feedback, reducing the need for frequent updates by tracking channel evolution and reducing feedback overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current CSI reporting formats are used in fast-fading channels, then channel state information can be provided, but feedback overhead increases due to frequent updates
Solution Approach 1:
The precoder matrix is segmented into three independent components (spatial beam component, delay component, Doppler-frequency component), each selected from separate codebooks. This segmentation allows the UE to report CSI for each component separately, reducing the overall feedback overhead while maintaining accurate channel state information tracking in fast-fading channels.
Solution Approach 2:
The patent introduces a dynamic CSI reporting mechanism where the UE determines the precoder matrix based on channel conditions. The three-stage precoder structure enables adaptive selection of spatial, delay, and Doppler components according to channel variations, allowing the system to respond dynamically to fast-fading conditions without requiring frequent complete CSI updates.
2Reliability
If current CSI reporting formats are used, then channel state information can be tracked, but the frequency of updates must be high in fast-fading channels
Solution Approach 1:
By dividing the precoder matrix into three independent components (spatial beam, delay, Doppler-frequency), the system can track channel variations more efficiently. Each component can be updated independently based on its specific coherence time, reducing the need for frequent complete CSI updates while maintaining reliable channel tracking.
Solution Approach 2:
The patent changes the parameters used for CSI reporting by introducing a three-stage precoder structure with separate codebooks for spatial, delay, and Doppler-frequency components. This parameter transformation allows the system to capture channel evolution more effectively, improving tracking reliability without requiring proportional increases in update frequency.
3Measurement precision
If a full precoder matrix is reported, then accurate channel state information is provided, but UE calculation complexity increases
Solution Approach 1:
The precoder matrix is divided into three independent components, each selected from separate codebooks. This segmentation simplifies the UE's calculation task by breaking down the complex precoder selection into three separate, more manageable selections, reducing computational complexity while maintaining overall accuracy.
Solution Approach 2:
Instead of requiring the UE to calculate and report the complete precoder matrix, the patent uses partial action by selecting from predefined codebooks for each component. This approach reduces the computational burden on the UE while still providing accurate channel state information through the combined three-stage precoder structure.
Data Source
AI summary
A communication device for providing a channel state information, CSI, feedback in a wireless communication system includes a transceiver to receive a radio signal including downlink reference signals. The processorestimates an explicit CSI,selects a Doppler-delay precoder matrix for a composite Doppler-delay-beam three-stage precoder,calculates and reports to the transmitter a CSI feedback.The communication device selects from one or more codebooks a subset of D delay components and/or a subset of F Doppler-frequency components and uses the selected subset of delay components for each polarization and each spatial beam and/or the selected subset of Doppler-frequency components for each polarization, each spatial beam and each delay, when calculating the Doppler-delay precoder matrix.