Retransmitting Cancelled HARQ Feedback Using Type 3 Codebook
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Solution Overview
Problem
In wireless communication systems, particularly in 5G NR networks, the retransmission of cancelled Hybrid Automatic Repeat Request (HARQ) feedback is inefficient due to high feedback overhead, especially when multiple HARQ processes are involved, leading to increased latency and resource utilization issues.
Innovation Solution
Implementing a type 3 HARQ codebook for retransmitting cancelled HARQ feedback, which incorporates physical layer priority differentiation to minimize overhead by partitioning HARQ process IDs into groups based on priority levels, allowing for selective configuration of HARQ feedback resources and reducing unnecessary transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional HARQ feedback retransmission is used for multiple HARQ processes, then all feedback information can be transmitted, but feedback overhead increases significantly
Solution Approach 1:
The patent segments HARQ feedback transmission into two types: Type 3 HARQ codebook for cancelled feedback (containing only NACK or DTX indicators) and Type 1/2 HARQ codebook for regular feedback. This segmentation allows the system to transmit only essential information when feedback is cancelled, reducing overhead while maintaining information completeness when needed.
Solution Approach 2:
The patent applies partial action by transmitting a simplified version of HARQ feedback (Type 3 codebook with minimal bits) when feedback cancellation occurs, rather than transmitting the complete feedback information. This partial transmission reduces overhead significantly while still providing the necessary retransmission trigger for the base station.
2Loss of information
If all HARQ feedback is retransmitted regardless of priority, then no feedback is lost, but latency increases due to unnecessary transmissions
Solution Approach 1:
The patent assigns different qualities (priorities) to different HARQ processes and applies different transmission strategies accordingly. High-priority HARQ processes receive full feedback retransmission (Type 1/2 codebook) to ensure reliability, while low-priority processes use simplified retransmission (Type 3 codebook) to reduce latency. This local quality differentiation resolves the contradiction between reliability and latency.
Solution Approach 2:
The patent changes the feedback transmission parameter (codebook type) based on HARQ process priority and cancellation status. When feedback is cancelled and priority is low, the system switches to Type 3 codebook with reduced bits, thereby reducing transmission time and latency while maintaining acceptable reliability through the retransmission mechanism.
3Loss of information
If HARQ feedback resources are allocated for all processes, then all feedback can be transmitted, but resource utilization becomes inefficient
Solution Approach 1:
The patent implements dynamic resource allocation where the HARQ feedback codebook type and size are adjusted based on real-time conditions such as feedback cancellation status and process priority. Instead of statically allocating resources for all possible feedback scenarios, the system dynamically selects Type 3 codebook for cancelled low-priority feedback, optimizing resource utilization while maintaining transmission capability when needed.
Data Source
AI summary
A user equipment (UE) is configured to transmit cancelled hybrid automatic repeat request (HARQ) feedback. The UE generating HARQ feedback for one or more HARQ process corresponding to a component carrier (CC), identifies that a scheduled transmission for the HARQ feedback has been cancelled and retransmits the cancelled HARQ feedback using a type 3 HARQ codebook.