Type 3 HARQ-ACK Codebook Segmentation for URLLC
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Solution Overview
Problem
In Type 3 HARQ-ACK codebooks, high priority transmissions can cause low priority HARQ-ACK codebooks to be dropped, leading to inefficient resource usage and potential loss of data, as the UE typically reports the most recent instance of HARQ process IDs, which may correspond to high priority ACK/NACKs, resulting in unnecessary retransmissions.
Innovation Solution
Implementing a low priority mode where the UE reports the most recent low priority instance of HARQ process IDs, allowing retransmissions of low priority ACK/NACKs even if the HARQ process ID is associated with a more recent high priority ACK/NACK, by configuring a modified Type 3 HARQ-ACK codebook that is smaller than the standard Type 3 codebook.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE reports the most recent instance of HARQ process IDs in Type 3 HARQ-ACK codebooks, then high priority ACK/NACK can be reported promptly, but low priority ACK/NACK may be dropped and resources are wasted due to unnecessary retransmissions
Solution Approach 1:
The patent segments the HARQ-ACK codebook into high priority and low priority portions, allowing the UE to identify and report only the most recent low priority ACK/NACK instances that are not already covered by high priority reports. This segmentation enables selective reporting that avoids redundant retransmissions while maintaining reliability for both priority levels.
Solution Approach 2:
The patent implements dynamic priority handling where the UE adaptively determines which ACK/NACK instances to report based on the priority status of each HARQ process. The reporting behavior changes dynamically based on whether a HARQ process is associated with high or low priority traffic, optimizing resource usage while ensuring reliable delivery of critical acknowledgments.
2Reliability
If the UE drops low priority HARQ-ACK codebook when collision occurs with high priority codebook, then high priority transmission reliability is improved, but low priority data reporting completeness deteriorates
Solution Approach 1:
The patent applies preliminary action by having the UE proactively identify and buffer low priority ACK/NACK instances before potential collisions with high priority reports. The UE maintains a record of low priority acknowledgments and selectively reports them in subsequent opportunities, preventing information loss while preserving high priority transmission reliability.
Solution Approach 2:
The patent implements feedback mechanisms where the UE monitors the priority status of HARQ processes and adjusts its reporting behavior accordingly. The system provides feedback about which ACK/NACK instances have been reported versus those that remain pending, enabling the UE to make informed decisions about subsequent reporting to ensure complete low priority data transmission.
Data Source
AI summary
This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for Type 3 HARQ-ACK codebook enhancements for URLLC. A UE may receive a configuration for reporting HARQ-ACK feedback for a subset of HARQ process IDs included in a set of HARQ process IDs. The set of HARQ process IDs may be associated with a Type 3 HARQ-ACK codebook. The subset of HARQ process IDs may be associated with a modified Type 3 HARQ-ACK codebook that is smaller than the Type 3 HARQ-ACK codebook. The UE may receive, based on the configuration, a trigger for the modified Type 3 HARQ-ACK codebook and report, based on the trigger, the modified Type 3 HARQ-ACK codebook including the HARQ-ACK feedback for the subset of HARQ process IDs.