HARQ-ACK Feedback on LBT-Selected PUCCH Channels
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Solution Overview
Problem
The existing cross-carriers feedback mechanism in 3GPP Rel-15 NR is designed for licensed operations where the availability of the UL PCell and/or UL PSCell/PUCCH-SCell is certain, but in NR-U, these components are not always available due to listen before talk (LBT) operations or network configurations, leading to potential overload and inefficiencies in transmitting feedback information.
Innovation Solution
A method and system that allow flexible HARQ-ACK feedback transmission by configuring multiple PUCCH resources across channels based on Listen-before-talk (LBT) categories, channel occupancy, and failure statistics, enabling transmission on available channels even when PCell and/or PSCell are not always accessible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback information is transmitted on PCell or PSCell in unlicensed spectrum, then feedback transmission can be performed using existing mechanisms, but transmission may fail or be blocked due to LBT operations making these channels unavailable
Solution Approach 1:
The patent divides the feedback transmission mechanism into multiple independent transmission options across different channels (PCell, PSCell, and SCell). Instead of relying on a single feedback channel, the system segments feedback transmission across multiple carriers, allowing selective use of available channels based on LBT outcomes. This segmentation enables the system to maintain reliability by distributing feedback transmission across multiple potential pathways.
Solution Approach 2:
The patent implements dynamic channel selection for feedback transmission based on real-time LBT results. The system dynamically determines which channel (PCell, PSCell, or SCell) to use for feedback transmission depending on which channel is currently available. This dynamic adaptation allows the system to switch between different transmission channels based on changing channel availability conditions, resolving the contradiction between reliability and adaptability.
2Reliability
If multiple PUCCH resources are configured across multiple channels, then feedback transmission flexibility increases and reliability improves, but device complexity and signaling overhead increase
Solution Approach 1:
The patent configures multiple PUCCH resources with identical or similar parameters across different channels (PCell, PSCell, SCell), making them universally interchangeable for feedback transmission. Each PUCCH resource serves the same function (carrying HARQ-ACK feedback), but on different channels. This multi-functionality allows the system to use any available channel for feedback transmission without requiring complex channel-specific configurations, thereby improving reliability while limiting complexity growth.
Solution Approach 2:
The patent changes the channel parameter (frequency location) while keeping other PUCCH parameters (format, timing, resources) consistent across multiple channels. By varying only the essential channel identifier parameter and maintaining other parameters unchanged, the system achieves channel diversity for reliability while avoiding the complexity that would arise from configuring different parameters for each channel.
3Reliability
If feedback is transmitted on all available channels, then transmission success probability increases, but signaling overhead and processing load increase
Solution Approach 1:
The patent implements partial action by configuring and potentially using multiple PUCCH resources across different channels, but only actually transmitting feedback on the channel that is available and selected based on LBT results. The system prepares multiple options (excessive configuration) but uses only what is necessary (partial transmission), thereby improving transmission success probability while controlling signaling overhead by avoiding redundant transmissions on all configured channels simultaneously.
Data Source
AI summary
A method, system and apparatus are disclosed for transmitting feedback information when operating in unlicensed portions of the radio frequency spectrum. In one embodiment, a wireless device is configured to receive a configuration for a 5 plurality of channels, the configuration configuring each of the plurality of channels with at least one physical uplink control channel, PUCCH, resource; and transmit feedback on the at least one PUCCH resource that is configured in at least one channel of the plurality of channels. In another embodiment, a network node is configured to transmit a configuration for a plurality of channels, the configuration 10 configuring each of the plurality of channels with at least one physical uplink control channel, PUCCH, resource; and receive feedback on the at least one PUCCH resource that is configured in at least one channel of the plurality of channels.