HARQ Feedback Resource Selection in Unlicensed Spectrum
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Solution Overview
Problem
In LTE systems, particularly in 5G new radio (NR), the time delay between data transmission and HARQ feedback results in challenges for terminals to successfully feed back HARQ results over unlicensed spectra, as they must contend for channel usage, and existing methods may not be suitable for unlicensed spectrum operations.
Innovation Solution
Configuring target indication information at the base station to indicate frequency domain resource identification for terminals, allowing them to determine a suitable frequency domain resource for HARQ feedback from a preset resource and candidate resources, using listen before talk (LBT) to ensure successful channel contention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station instructs a terminal to feed back an HARQ result in a certain bandwidth part (BWP), then the HARQ feedback mechanism is established, but the terminal cannot feed back the HARQ result if it does not successfully contend for the current channel in unlicensed spectrum
Solution Approach 1:
The patent makes the HARQ feedback mechanism dynamic by allowing the terminal to adaptively select from multiple candidate BWPs based on channel contention results. Instead of a fixed feedback location, the system dynamically adjusts the feedback BWP according to actual channel access conditions, resolving the contradiction between reliable feedback and channel access adaptability in unlicensed spectrum
Solution Approach 2:
The patent changes the parameter of feedback resource selection from a fixed base station-instructed BWP to a flexible terminal-selected BWP from multiple candidates. The base station configures multiple candidate BWPs with different characteristics, and the terminal selects the appropriate one based on channel contention outcomes, enabling adaptation to unlicensed spectrum conditions while maintaining feedback reliability
2Ease of operation
If a preset frequency domain resource is used for HARQ feedback, then the feedback location is determined, but the terminal fails to feed back the HARQ result when channel contention fails
Solution Approach 1:
The patent applies preliminary action by having the base station pre-configure multiple candidate frequency domain resources (BWPs) before the terminal needs to perform HARQ feedback. These candidate resources are prepared in advance with different characteristics, allowing the terminal to quickly select an appropriate resource based on channel contention results without complex real-time calculations, thus maintaining ease of operation while improving feedback success rate
Solution Approach 2:
The patent introduces candidate BWPs as intermediary resources between the preset feedback location and the actual channel conditions. These intermediary resources serve as alternative pathways for feedback transmission, allowing the terminal to bypass blocked channels by selecting from pre-configured candidates, thereby improving reliability without complicating the feedback mechanism
3Adaptability or versatility
If multiple candidate frequency domain resources are configured, then the terminal has more options for feedback, but the indication information complexity increases
Solution Approach 1:
The patent segments the feedback resource indication into multiple independent candidate BWPs, each with its own identification and characteristics. Instead of one complex resource description, the system divides the indication into several simpler candidate options, making it easier to manage and select from while maintaining high adaptability. The base station can indicate which candidate to use through simplified signaling
Solution Approach 2:
The patent enables self-service by allowing the terminal to autonomously select the appropriate feedback resource from the configured candidates based on its channel contention results. The terminal uses pre-configured selection criteria and its own channel sensing outcomes to make the selection without requiring complex real-time instructions from the base station, reducing indication information complexity while maintaining flexibility
Data Source
AI summary
The present disclosure provides a hybrid automatic repeat request (HARQ) feedback method and apparatus. The method includes: configuring target indication information for a terminal, wherein the target indication information is used to indicate frequency domain resource identification information corresponding to at least one first candidate frequency domain resources; sending the target indication information to the terminal; after a physical downlink shared channel (PDSCH) is sent to the terminal, receiving an HARQ result for the PDSCH fed back by the terminal through the target frequency domain resource; wherein the target frequency domain resource is a frequency domain resource for carrying the HARQ result determined by the terminal from a preset frequency domain resource and at least one first candidate frequency domain resources.