HARQ Codebook Determination Across Channel Groups in NR
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Solution Overview
Problem
In New Radio (NR) systems operating on unlicensed frequency bands, determining Hybrid Automatic Repeat reQuest (HARQ) codebooks for Physical Downlink Shared Channels (PDSCHs) is challenging due to the need for flexible and efficient HARQ feedback mechanisms that accommodate dynamic scheduling and potential LBT failures.
Innovation Solution
A method and device for determining HARQ codebooks by consecutively counting Downlink assignment indexes (DAIs) across multiple channel groups, enabling consistent HARQ codebook generation and feedback on uplink resources, even in the presence of LBT failures, through grouping and placeholder information to ensure alignment between network devices and terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DAIs are counted separately for each channel group, then the HARQ codebook can be determined for each channel group independently, but the complexity of determining the HARQ codebook increases and alignment between network devices and terminals becomes difficult to maintain
Solution Approach 1:
The patent merges the DAI counting process across multiple channel groups into a single continuous sequence. Instead of resetting the counter for each channel group, the DAI values are counted consecutively across all channel groups, forming a unified HARQ codebook structure that simplifies the determination process and maintains alignment between network devices and terminals.
2Reliability
If placeholder information is added for missing PDSCHs, then the HARQ codebook can maintain consistent structure and alignment, but the size of the HARQ codebook increases
Solution Approach 1:
The patent applies preliminary action by pre-determining the complete HARQ codebook structure based on the continuous DAI counting sequence before actual PDSCH transmissions occur. The codebook is configured with fixed positions for all possible PDSCHs across multiple channel groups, allowing placeholder information to be placed in advance for potential missing transmissions, thereby ensuring consistent alignment without increasing the actual data payload.
3Device complexity
If consecutive DAI counting is used across multiple channel groups, then the HARQ codebook determination is simplified and alignment is improved, but the ability to handle LBT failures in unlicensed bands becomes more challenging
Solution Approach 1:
The patent applies dynamics by making the HARQ codebook structure flexible enough to accommodate LBT failures while maintaining the simplified continuous counting mechanism. The codebook can dynamically adjust to include or exclude specific channel groups based on transmission success, allowing the system to handle LBT failures without complicating the fundamental DAI counting process.
Data Source
AI summary
A method includes: a terminal device receives first Downlink Control Information (DCI), wherein the first DCI is used for scheduling a first Physical Downlink Shared Channel (PDSCH), the terminal device determines a first uplink resource, the first uplink resource being used for feeding back a first HARQ codebook corresponding to at least one of a plurality of channel groups, wherein downlink allocation indicators (DAIs) corresponding to the PDSCHs in the plurality of channel groups are consecutively counted; the terminal device determines the first HARQ codebook for the first uplink resource. By consecutively counting DAIs corresponding to PDSCHs in the plurality of channel groups, the present application can implement consistent understanding of the sizes of HARQ codebooks corresponding to the plurality of channel groups by a terminal device and a network device.