User Equipment LBT Failure Feedback via PUCCH
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Solution Overview
Problem
In thing-to-thing direct-connection communication systems or sidelink communication systems, when a data packet needs to be transmitted over an unlicensed band, listen before talk (LBT) failures occur due to occupied transmission resources, preventing data packet transmission and subsequent feedback to the network device.
Innovation Solution
The user equipment sends a negative acknowledgement (NACK) or acknowledgement (ACK) to the network device on a target physical uplink control channel (PUCCH) when an LBT failure indication is received, allowing for hybrid automatic repeat request (HARQ) feedback and potentially obtaining a new transmission resource.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If listen before talk (LBT) is performed before transmitting data packet on unlicensed band resource, then transmission collision is avoided, but transmission failure occurs when resource is occupied by other user equipment
Solution Approach 1:
The patent implements HARQ feedback mechanism where the receiving end sends ACK/NACK feedback to the transmitting end. When LBT failure occurs, the transmitting end can send NACK feedback to indicate transmission failure, enabling the network device to reconfigure transmission resources. This feedback loop resolves the contradiction by providing a mechanism to handle transmission failures caused by LBT while maintaining overall system reliability.
Solution Approach 2:
The patent performs LBT procedure before actual data transmission to check if the unlicensed band resource is available. This preliminary action prevents transmission collisions and identifies occupied resources in advance, allowing the system to switch to alternative resources (licensed band or other unlicensed resources) before transmission failure occurs, thus maintaining productivity while ensuring reliability.
2Reliability
If HARQ feedback is sent on target PUCCH corresponding to first transmission resource, then feedback channel availability is ensured, but feedback cannot be sent when LBT failure prevents uplink transmission
Solution Approach 1:
The patent introduces the network device as an intermediary in the feedback process. When the user equipment experiences LBT failure and cannot send feedback directly, the network device receives and processes the feedback information (ACK/NACK) and manages the HARQ process. This intermediary approach ensures feedback delivery reliability while simplifying the operation for user equipment, as they only need to send feedback when able without managing complex fallback mechanisms.
3Adaptability or versatility
If unlicensed band resource is used for transmission, then spectrum utilization is improved, but transmission availability decreases due to LBT failures
Solution Approach 1:
The patent implements dynamic resource selection where the system can switch between licensed band resources and unlicensed band resources based on LBT outcomes and channel conditions. When unlicensed band transmission fails due to LBT, the system dynamically transitions to alternative resources. This dynamic approach maintains high spectrum utilization flexibility while ensuring transmission availability through multiple resource options.
Solution Approach 2:
The patent changes the transmission resource parameter (from unlicensed band to licensed band or other unlicensed resources) when LBT failure occurs. The network device can reconfigure the transmission resource based on feedback, changing the frequency band or time resource parameters to ensure successful transmission while maintaining overall spectrum utilization efficiency.
Data Source
AI summary
A feedback method, a user equipment, and a storage medium are provided in implementations of the disclosure. In the feedback method, when a data packet of a second user equipment is to be transmitted and the second user equipment receives a listen before talk (LBT) failure indication, the second user equipment sends a negative acknowledgement (NACK) or an acknowledgement (ACK) to a network device on a target physical uplink control channel (PUCCH), where the target PUCCH is a PUCCH corresponding to a first transmission resource used for transmitting the data packet.