HARQ-Less Downlink Feedback for Faster NTN Disruption Detection
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Solution Overview
Problem
In wireless communication systems, particularly in non-terrestrial network (NTN) deployments, the lack of hybrid automatic repeat request (HARQ) feedback leads to excessive delays in identifying downlink transmission disruptions, resulting in lost communications and inefficient bandwidth usage, as well as challenges in adapting scheduling modulation and coding schemes without accurate channel quality feedback.
Innovation Solution
Implementing downlink feedback mechanisms in HARQ-less transmission modes, where UEs provide physical-layer feedback via the physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH) to enable the base station to adapt scheduling modulation and coding schemes, and configuring the reordering timer to zero or disabling it to allow out-of-order delivery, thereby reducing delays and improving resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If HARQ feedback is disabled for NTN deployments, then transmission simplicity is improved, but downlink disruption identification delay increases excessively
Solution Approach 1:
The patent implements a feedback mechanism where the UE transmits downlink decoding feedback information to the BS via PUCCH or PUSCH. This feedback loop enables the BS to identify downlink disruptions and adapt scheduling parameters without requiring full HARQ retransmission procedures, thus resolving the contradiction between transmission simplicity and disruption identification speed.
Solution Approach 2:
The patent introduces downlink decoding feedback information as an intermediary signal between the UE and BS. This feedback acts as a mediator that conveys channel quality and decoding status, enabling the BS to make scheduling adaptations without the need for complex HARQ processes, thereby reducing disruption identification delay while maintaining transmission simplicity.
2Loss of energy
If HARQ feedback is disabled, then retransmission overhead is reduced, but bandwidth utilization efficiency deteriorates
Solution Approach 1:
The patent employs downlink decoding feedback to enable the BS to adapt scheduling modulation and coding schemes based on actual channel conditions. This feedback mechanism allows the system to optimize bandwidth utilization by selecting appropriate MCS values without requiring HARQ retransmissions, thus improving productivity while reducing retransmission overhead.
Solution Approach 2:
The patent implements dynamic adaptation of scheduling parameters based on real-time feedback information. The BS adjusts modulation and coding schemes dynamically according to channel quality reports from the UE, optimizing bandwidth efficiency without the need for fixed HARQ retransmission protocols, thereby resolving the contradiction between overhead reduction and productivity improvement.
3Loss of time
If HARQ feedback is disabled, then feedback delay is reduced, but scheduling adaptation capability deteriorates
Solution Approach 1:
The patent implements a feedback mechanism that provides timely downlink decoding status information to the BS. This feedback enables the BS to adapt scheduling parameters in a timely manner, maintaining scheduling adaptation capability while reducing feedback delay compared to traditional HARQ processes. The feedback is transmitted via PUCCH or PUSCH with optimized timing.
Solution Approach 2:
The patent enables the BS to perform preliminary scheduling adaptations based on feedback information received before the next transmission opportunity. By processing feedback and preparing scheduling decisions in advance, the system maintains adaptability while minimizing delay, as the BS can immediately apply adapted parameters when the next transmission slot becomes available.
4Stability of the object's composition
If reordering timer is configured to non-zero value, then in-order delivery is ensured, but transmission flexibility is reduced
Solution Approach 1:
The patent enables dynamic configuration of the reordering timer parameter based on transmission conditions. The timer can be set to zero or disabled to allow out-of-order delivery when flexibility is needed, or set to non-zero values to ensure in-order delivery when stability is prioritized. This parameter adaptability resolves the contradiction between delivery stability and transmission flexibility.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine that a hybrid automatic repeat request (HARQ)-less mode is activated for communication with a base station (BS). The UE may configure a reordering timer based at least in part on the HARQ-less mode being activated for communication with the BS. Numerous other aspects are provided.