HARQ Feedback Retransmission Across Time-Frequency Resources
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Solution Overview
Problem
In wireless communication systems, particularly in 5G NR-U, HARQ information feedback is not timely due to LBT failures and interference, leading to increased data processing latency, which is critical for URLLC services requiring ultra-reliability and low latency.
Innovation Solution
A method for generating and retransmitting HARQ information on a different time-frequency resource when initial transmission fails, allowing for flexible HARQ retransmission based on data priority and group differences, and utilizing indication mechanisms to optimize HARQ information transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT is performed before signal transmission in NR-U system, then channel access reliability is improved, but HARQ feedback timeliness deteriorates due to possible LBT failures
Solution Approach 1:
The patent applies dynamics by making the time-frequency resource for HARQ feedback flexible rather than fixed. The receiving device can dynamically select different time-frequency resources for retransmitting HARQ information based on channel conditions and LBT outcomes, allowing the system to adapt to varying reliability requirements while maintaining feedback timeliness.
Solution Approach 2:
The patent implements preliminary action by having the receiving device prepare multiple time-frequency resources for potential HARQ retransmission before the initial transmission completes. This advance preparation ensures that when LBT failure occurs, the receiving device can immediately switch to alternative resources without significant delay, thus reducing overall feedback latency.
2Ease of operation
If fixed time-frequency resource is used for HARQ feedback, then transmission procedure simplicity is improved, but adaptability to LBT failures deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the time-frequency resource space into multiple discrete resources that can be independently selected for HARQ feedback. Instead of using a single fixed resource, the system segments the available resources and allows the receiving device to choose from multiple options based on current channel conditions, thereby improving adaptability while maintaining manageable procedure complexity.
Solution Approach 2:
The patent implements parameter changes by allowing the time-frequency resource parameters (time offset, frequency allocation) to be dynamically adjusted based on LBT outcomes and channel conditions. This flexibility enables the system to adapt to various scenarios including LBT failures, while the changes follow predefined rules that maintain operational simplicity.
3Reliability
If HARQ retransmission is implemented, then feedback reliability is improved, but data processing latency increases
Solution Approach 1:
The patent applies dimensionality change by introducing an additional dimension of resource selection beyond the traditional single time slot. By utilizing both time and frequency dimensions together, the system can retransmit HARQ information on different time-frequency resources simultaneously or in parallel, thereby improving feedback reliability without proportionally increasing processing latency.
Data Source
AI summary
A HARQ information transmission method and apparatus, to resolve a problem that HARQ information is not fed back in a timely manner. When a first device cannot successfully send first hybrid automatic repeat request (HARQ) information on a first time-frequency resource, or a second device cannot successfully receive the first HARQ information on the first time-frequency resource, the first device retransmits the first HARQ information on a second time-frequency resource for transmitting second HARQ information corresponding to second data. First data and the second data may be data with different priorities and/or in different groups. In this way, HARQ retransmission flexibility can be improved, and the first HARQ information is transmitted in a timelier manner, so that a data processing latency is reduced as much as possible.