HARQ Grant Timer Control for LBT Delays in NR Uplink
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Solution Overview
Problem
In New Radio (NR) wireless communication, the increased risk of channel unavailability due to multiple Listen Before Talk (LBT) processes for uplink data transmission in unlicensed bands, particularly in configured scheduling schemes, is not effectively addressed by existing HARQ feedback mechanisms.
Innovation Solution
Adaptive management of configuredGrantTimer based on HARQ feedback, allowing for timer restart or stop based on HARQ ACK/NACK, and prioritization of HARQ processes to optimize channel utilization and reduce transmission failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple LBT processes are performed for uplink data transmission in unlicensed bands, then channel access reliability is improved, but channel access efficiency deteriorates due to increased risk of channel unavailability
Solution Approach 1:
The patent implements dynamic HARQ process management where the configuredGrantTimer can be restarted or stopped based on HARQ feedback (ACK/NACK). This dynamic adjustment allows the system to adapt to channel conditions in unlicensed bands, maintaining reliability while improving efficiency by preventing premature timer expiration that would waste HARQ processes during channel access delays caused by multiple LBT processes
Solution Approach 2:
The patent utilizes HARQ feedback mechanisms to control the configuredGrantTimer behavior. When HARQ feedback indicates successful transmission (ACK), the timer is stopped; when transmission fails (NACK) or channel access is delayed due to LBT processes, the timer is restarted. This feedback-driven approach ensures reliable retransmissions while optimizing channel access efficiency by keeping HARQ processes available longer when needed
2Productivity
If configured scheduling is used to reduce LBT processes, then channel access efficiency is improved, but transmission reliability deteriorates due to omitted LBT processes at gNB and UE
Solution Approach 1:
The patent applies dynamic timer management to configured scheduling by allowing the configuredGrantTimer to be restarted upon receiving NACK feedback or when channel access is delayed. This dynamic adjustment maintains transmission reliability despite the reduced LBT processes in configured scheduling, as the timer extension ensures HARQ processes remain available for potential retransmissions
Solution Approach 2:
The patent leverages HARQ feedback to control timer behavior in configured scheduling scenarios. The feedback mechanism ensures that even though LBT processes are omitted, transmission reliability is maintained through timer restarts triggered by NACK feedback, allowing the system to recover from transmission failures without requiring additional LBT processes
3Device complexity
If configuredGrantTimer is fixed without adaptive management, then system complexity is reduced, but transmission efficiency deteriorates due to inability to handle channel unavailability in unlicensed bands
Solution Approach 1:
The patent implements adaptive timer management where the configuredGrantTimer behavior dynamically changes based on HARQ feedback and channel conditions. The timer can be restarted or stopped adaptively, which significantly improves transmission efficiency in unlicensed bands by preventing premature HARQ process expiration during channel access delays, while adding only minimal control logic complexity
Solution Approach 2:
The patent changes the timer parameter behavior from fixed to adaptive by introducing HARQ feedback-dependent timer restart and stop conditions. This parameter change allows the system to respond to channel conditions in unlicensed bands, improving transmission efficiency without requiring complex reconfiguration, as the timer behavior adjusts automatically based on simple ACK/NACK feedback
Data Source
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AI summary
The present disclosure provides a method (100) in a terminal device for facilitating Hybrid Automatic Repeat reQuest (HARQ) transmission. The method (100) includes: starting (110), upon transmitting data to a network device in a first HARQ transmission using a first HARQ process, a first configured grant timer associated with first the HARQ process; receiving (120) from the network device HARQ feedback information associated with the first HARQ transmission; and applying (130) a timer operation to the first configured grant timer based on the HARQ feedback information.