HARQ-ACK Codebook Grouping for Large PDSCH Feedback
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Solution Overview
Problem
The size of the Hybrid Automatic Repeat Request (HARQ) codebook becomes excessively large due to the combination of HARQ-ACK feedback for multiple Physical Downlink Shared Channel (PDSCH) groups in the same Physical Uplink Control Channel (PUCCH), leading to inefficiencies in data transmission.
Innovation Solution
Implementing a method to reduce the HARQ-ACK codebook size by grouping PDSCH transmissions into sub-groups and applying bundling rules such as CBG-based, spatial, time domain, and carrier domain bundling, or triggering one-shot HARQ-ACK feedback when the codebook exceeds a configured maximum size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HARQ-ACK feedback for multiple PDSCH groups is combined in the same codebook, then comprehensive feedback coverage is improved, but codebook size becomes excessively large
Solution Approach 1:
The patent divides the HARQ-ACK codebook into multiple sub-codebooks, where each sub-codebook corresponds to a specific PDSCH group identified by a group index. This segmentation allows the feedback for different PDSCH groups to be organized separately, preventing the codebook from becoming excessively large while maintaining comprehensive feedback coverage across all groups.
2Loss of information
If HARQ-ACK feedback for all PDSCH groups is transmitted together, then feedback completeness is improved, but transmission efficiency deteriorates due to large codebook size
Solution Approach 1:
By segmenting the codebook into sub-codebooks for different PDSCH groups, the patent enables more efficient transmission. The UE can selectively transmit relevant sub-codebooks based on which PDSCH groups require feedback, reducing unnecessary transmission overhead while ensuring all required feedback is delivered.
Solution Approach 2:
The patent introduces dynamic mechanisms where the BS can independently request feedback for specific PDSCH groups using group indices in DCI messages. This dynamic approach allows the feedback transmission to adapt to actual needs, improving efficiency by transmitting only necessary feedback rather than always sending complete codebooks.
3Reliability
If PUCCH retransmission is requested for failed HARQ-ACK transmission, then feedback reliability is improved, but additional transmission overhead increases
Solution Approach 1:
The patent enables dynamic HARQ-ACK feedback requests where the BS can independently indicate which PDSCH groups require feedback using group indices in DCI. This dynamic mechanism allows selective retransmission requests for specific groups, reducing unnecessary retransmission overhead while maintaining reliability for groups that actually need feedback.
Data Source
AI summary
The present application relates to a method and apparatus for determining a HARQ-ACK codebook. One embodiment of the subject application provides a method including receiving a signal requesting transmission of Hybrid Automatic Repeat request-Acknowledgement (HARQ-ACK) feedback for both a first group of Physical Downlink Shared Channel (PDSCH) transmissions and a second group of PDSCH transmission in a HARQ-ACK codebook, wherein each PDSCH transmission of the first group of PDSCH transmissions has an associated Downlink Control Information (DCI) indicating a first group index, and each PDSCH transmission of the second group of PDSCH transmissions has an associated DCI indicating a second group index; and transmitting the HARQ-ACK codebook.