Dynamic Resource Switching for LBT Failures in Unlicensed Spectrum
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Solution Overview
Problem
In the unlicensed spectrum, Listen Before Talk (LBT) failures in 5G networks lead to transmission issues, such as unsuccessful random access channel (RACH) messages and handover failures due to interference from existing wireless transmissions like Wi-Fi, necessitating a method to reduce LBT failure impact.
Innovation Solution
A dynamic resource switching method where User Equipment (UE) performs LBT attempts over current resources during a RACH procedure and switches to new resources when a pre-configured failure threshold is reached, incorporating a failure count that increments for both LBT and Reference Signal Received Power (RSRP) failures, ensuring reliable transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If LBT is performed before each transmission in unlicensed spectrum, then coexistence with Wi-Fi is ensured, but transmission success rate decreases due to LBT failures
Solution Approach 1:
The patent implements dynamic resource switching where the UE monitors LBT failure counts and switches between different resource sets (first and second resources) based on failure thresholds. This dynamic adaptation allows the system to respond to changing channel conditions and reduce the impact of LBT failures on transmission success.
Solution Approach 2:
The patent changes the parameter of resource selection based on LBT failure statistics. By tracking failure counts and comparing them against thresholds, the system adjusts which resource set to use, thereby modifying transmission parameters to optimize success rate while maintaining coexistence.
2Reliability
If LBT is performed before RACH preamble transmission, then channel availability is checked, but handover fails when LBT fails during handover procedure
Solution Approach 1:
The patent applies dynamic resource switching during handover procedures. When LBT failures are detected in the current resource set, the UE dynamically switches to alternative resources for handover transmission, ensuring handover continuity and preventing handover failure due to LBT failures.
Solution Approach 2:
The system implements feedback mechanisms where the UE monitors LBT outcomes and uses this information to adjust resource selection. This feedback loop ensures that handover procedures can adapt to channel conditions and maintain success rate even when initial LBT attempts fail.
3Reliability
If multiple LBT attempts are performed on same resources, then transmission opportunity increases, but time consumption increases
Solution Approach 1:
The patent dynamically switches between resource sets based on LBT failure counts and thresholds. This prevents endless LBT attempts on failing resources by automatically transitioning to alternative resources, thereby limiting time consumption while maintaining transmission opportunities.
Solution Approach 2:
The system uses feedback from LBT outcomes to determine when to switch resources. By monitoring failure counts and comparing them against configured thresholds, the system avoids redundant time-consuming LBT attempts on unsuccessful resources and efficiently transitions to viable alternatives.
Data Source
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Figure 2A~2B
Figure 3A
AI summary
A method and a user equipment of performing resource switching in an unlicensed spectrum are provided. A current set of resources in the unlicensed spectrum is utilized by a UE for performing LBT attempts for transmission of an RACH message to a base station. One or more LBT attempts for transmissions from the UE to the base station are performed over the current set of resources during a current RACH procedure. The current set of resources is switched to a new set of resources in the unlicensed spectrum to be utilized by the UE in a new RACH procedure after a failure count reaches a pre-configured threshold during the current RACH procedure. The failure count is calculated at least based on a count of LBT failure over the current set of resources during the current RACH procedure.