Terminal Device HARQ Feedback Triggering for 5G URLLC Latency
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Solution Overview
Problem
Current designs for HARQ feedback in 5G networks, such as those for URLLC, face challenges in achieving high-reliability and low-latency due to increased uplink signaling overhead and undesirable HARQ Round Trip Time (RTT) caused by non-ideal backhaul links, which are not efficiently addressed by existing methods.
Innovation Solution
A method and apparatus for data transmission feedback that involves a timer-based approach, where a terminal device determines whether to trigger feedback based on received data packets, monitored network devices, and channel quality, allowing for optimized ACK/NACK feedback to be sent only when necessary, thereby reducing latency and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACK/NACK feedback repetition is used to improve reliability, then feedback reliability is improved, but uplink signaling overhead increases unacceptabley
Solution Approach 1:
Instead of repeating feedback a fixed maximum number of times (6 aggregated subframes), the patent applies partial action by triggering feedback only when necessary based on timer expiration or channel quality conditions. This selective feedback mechanism reduces unnecessary repetitions while maintaining reliability when needed.
Solution Approach 2:
The patent changes the feedback triggering parameters from fixed repetition counts to dynamic timer-based expiration and channel quality threshold conditions. This allows the system to adapt feedback behavior to actual transmission conditions, reducing overhead when channel quality is good while ensuring feedback when needed.
2Loss of time
If processing delay between data and feedback is reduced to meet low-latency requirements, then feedback latency is reduced, but HARQ RTT increases due to non-ideal backhaul links
Solution Approach 1:
The patent applies preliminary action by starting a timer upon receiving the data packet before the feedback is actually transmitted. This timer expiration mechanism ensures that feedback is triggered promptly when the data transmission completes, reducing processing delay while the timer itself accounts for the backhaul link latency in determining when feedback should be sent.
Solution Approach 2:
The patent uses feedback mechanisms where the terminal device monitors channel quality and timer expiration conditions to determine when to trigger feedback. This feedback loop adapts to actual transmission conditions and backhaul link characteristics, optimizing the balance between processing speed and reliability.
3Reliability
If feedback is sent continuously to ensure reliability, then feedback reliability is improved, but uplink resource consumption increases
Solution Approach 1:
Instead of continuous feedback transmission, the patent implements periodic action through timer-based triggering. The timer is started when data is received and expires after a predetermined period, triggering feedback only when necessary. This periodic mechanism reduces uplink resource consumption by avoiding unnecessary continuous transmissions while maintaining reliability through timely feedback when the timer expires.
Solution Approach 2:
The terminal device performs self-service by autonomously monitoring channel quality and timer expiration conditions to determine when to trigger feedback. This self-triggering mechanism eliminates the need for continuous network-controlled feedback scheduling, reducing uplink resource consumption while ensuring feedback is sent when the transmission conditions require it.
Data Source
AI summary
Embodiments of the disclosure generally relate to data transmission feedback. A terminal device receives a data packet transmitted from one or more network devices of the plurality of network device and determine whether triggering a feedback based on one or more of the received data packet, the monitored network devices and a timer Y at the terminal device. Latency for feedback of data transmission can be reduced and reliability can be improved.