LBT Failure Detection and Recovery in 5G NR UEs
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Solution Overview
Problem
Next-generation wireless communication systems, such as 5G NR, face challenges in consistent Listen Before Talk (LBT) failure detection and recovery, particularly in managing UL BWP failures across multiple cells, which can lead to unwanted delays in UL transmissions due to hidden node issues and unpredictable channel conditions.
Innovation Solution
The method involves a UE triggering consistent LBT failure procedures and SR procedures for detected failures on multiple Bandwidth Parts (BWP) of cells, receiving indications for BWP switching from the Base Station (BS), and selectively canceling these procedures to optimize resource allocation and prevent unnecessary actions, ensuring timely UL transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE triggers LBT failure procedures and SR procedures for all detected failures on multiple BWPs, then the detection coverage is improved, but the system complexity and unnecessary transmissions increase
Solution Approach 1:
The patent segments the LBT failure management by associating each failure procedure with a specific BWP and cell identifier. When BWP switching occurs, the UE selectively cancels procedures only for the switched BWP while maintaining procedures for other BWPs. This segmentation allows comprehensive failure detection across multiple BWPs without requiring uniform cancellation of all procedures, thus improving reliability while managing complexity.
Solution Approach 2:
The patent implements dynamic procedure management where the UE maintains multiple LBT failure procedures and SR procedures simultaneously for different BWPs, and dynamically cancels specific procedures based on BWP switching events. This dynamic approach allows the system to adapt to changing channel conditions and BWP configurations, improving detection coverage while avoiding unnecessary actions on unaffected BWPs.
2Reliability
If the UE maintains multiple LBT failure procedures simultaneously for multiple BWPs, then the reliability is improved, but the time management and resource allocation become more complex
Solution Approach 1:
The patent applies preliminary action by having the UE pre-configure multiple LBT failure procedures and SR procedures for different BWPs before failures occur. When BWP switching is indicated, the UE immediately cancels the procedure for the switched BWP without waiting for failure detection, preventing wasted time on procedures that would no longer be relevant. This preliminary cancellation mechanism reduces coordination time while maintaining reliability for active BWPs.
3Productivity
If the UE cancels LBT failure procedures upon BWP switching, then unnecessary transmissions are prevented, but the response time to BWP changes must be optimized
Solution Approach 1:
The patent implements feedback mechanisms where the UE monitors BWP switching indications from the gNB and provides immediate feedback by canceling LBT failure procedures for the switched BWP. This feedback loop ensures that the UE responds quickly to BWP changes, preventing unnecessary transmissions on deactivated BWPs while maintaining efficient uplink transmissions on active BWPs, thus improving overall transmission efficiency.
Data Source
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AI summary
A method performed by a UE for Listen Before Talk (LBT) failure detection and recovery includes the UE triggering a first consistent LBT failure procedure for a first consistent LBT failure detected on a first Bandwidth Part (BWP) of a first cell of a Base Station (BS); triggering a second consistent LBT failure procedure for a second consistent LBT failure detected on a second BWP of a second cell of the BS; triggering a first Scheduling Request (SR) procedure for the first consistent LBT failure; triggering a second SR procedure for the second consistent LBT failure; receiving, from the BS, an indication for BWP switching of the first cell; switching an active BWP of the first cell based on the indication; canceling the first consistent LBT failure procedure in response to receiving the indication; and canceling the first SR procedure in response to receiving the indication.