Enhanced Type-3 HARQ-ACK Codebook Feedback Trigger Rules
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Solution Overview
Problem
The Type-3 codebook in R17 URLLC has high overhead, and there is a need to reduce feedback overhead for Semi-Persistent Scheduling (SPS) Physical Downlink Shared Channel (PDSCH), particularly in determining when to trigger enhanced Type-3 HARQ-ACK codebook feedback and calculating its size due to resource reservation uncertainties.
Innovation Solution
A method is introduced to trigger enhanced Type-3 HARQ-ACK codebook feedback based on predefined rules, such as fixed trigger periods, thresholds, and UE caching capabilities, ensuring both base stations and terminals can accurately calculate and report the codebook size, thereby reducing misunderstandings and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Type-3 codebook is used for retransmission of HARQ-ACK, then reliability of HARQ-ACK delivery is improved, but feedback overhead increases
Solution Approach 1:
The patent segments the HARQ-ACK feedback mechanism by introducing separate codebook types (Type-1 for initial transmission, Type-2 for retransmission) and further dividing Type-2 into Type-2a (with DCI) and Type-2b (without DCI). This segmentation allows the system to use the appropriate codebook type based on specific transmission scenarios, reducing unnecessary feedback overhead while maintaining reliability for retransmissions.
Solution Approach 2:
The patent implements dynamic triggering mechanisms for Type-3 codebook feedback using DCI messages with specific trigger bits. The codebook generation and transmission are dynamically activated only when needed (upon receiving trigger DCI), rather than being continuously transmitted. This dynamic approach reduces feedback overhead by eliminating redundant transmissions while ensuring reliability when retransmission is actually required.
2Measurement precision
If enhanced Type-3 codebook is triggered frequently, then codebook size accuracy is improved, but feedback overhead increases
Solution Approach 1:
The patent applies partial action by triggering Type-3 codebook feedback only under specific conditions (resource collision detection, priority-based preemption) rather than continuously. The trigger DCI includes conditional logic that activates codebook feedback only when partial conditions are met (e.g., when HARQ-ACK resources collide or when high-priority traffic preempts low-priority resources), reducing unnecessary feedback while maintaining accurate codebook size determination when needed.
Solution Approach 2:
The patent changes the triggering parameter from continuous feedback to event-driven feedback based on specific conditions. The DCI trigger bit acts as a parameter change that switches the feedback mechanism between active (when collision or preemption occurs) and inactive (normal operation) states. This parameter-based control ensures accurate codebook size determination only when necessary, reducing overall feedback overhead.
3Productivity
If SPS PDSCH resource reservation is extended, then communication efficiency is improved, but codebook size calculation complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring SPS PDSCH parameters (period, offset, resource allocation) through RRC signaling before actual transmission. The network pre-establishes the SPS configuration including the periodicity and resource allocation patterns, allowing the terminal to predict future SPS resource locations without complex real-time calculations. This preliminary configuration simplifies codebook size calculation while maintaining communication efficiency through extended resource reservation.
Solution Approach 2:
The patent introduces DCI messages as intermediaries that carry trigger bits and activation/deactivation commands for SPS PDSCH. Instead of directly managing complex SPS resource reservations, the network uses DCI as an intermediary layer to simplify terminal operations. The DCI trigger bit acts as a mediator that activates pre-configured SPS resources, reducing the computational complexity at the terminal while maintaining efficient resource utilization through network-controlled activation.
Data Source
AI summary
A codebook feedback method is performed by a terminal, and includes: reporting an enhanced Type 3 Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) codebook to an access network device in response to a trigger rule being satisfied.