UE Conditional Resume for Unlicensed-Band Handover Recovery
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Solution Overview
Problem
Existing mobile communication systems face challenges in effectively providing services due to listen-before-talk (LBT) failures in unlicensed frequency bands, leading to handover failures and increased latency in next-generation wireless communication systems.
Innovation Solution
A method and apparatus for a user equipment (UE) to perform a conditional resume process by using pre-suspend configuration information to self-trigger a resume in a neighboring cell based on predefined conditions, avoiding direct LBT failures and ensuring seamless handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE uses traditional handover procedure in unlicensed frequency bands, then the handover can be performed, but LBT failure occurs causing handover failure and increased latency
Solution Approach 1:
The gNB performs preliminary actions by transmitting pre-suspend configuration information to the UE before actual handover is needed. This configuration includes resume conditions and neighboring cell information, allowing the UE to prepare for autonomous resume without waiting for traditional handover signals, thereby reducing latency and avoiding LBT failures
Solution Approach 2:
The UE performs self-service by autonomously triggering resume procedure in a neighboring cell when predefined resume conditions are met. The UE independently evaluates conditions, selects appropriate neighboring cells, and executes resume without requiring continuous network control, enabling fast recovery from LBT failures and reducing handover latency
2Loss of time
If the UE performs autonomous resume in neighboring cell based on pre-suspend configuration, then handover latency is reduced and service continuity is maintained, but the system complexity increases due to conditional resume process
Solution Approach 1:
The gNB transmits pre-suspend configuration information containing resume conditions and neighboring cell details before handover is needed. This preliminary preparation simplifies the UE's autonomous resume process by providing all necessary decision criteria in advance, reducing the complexity burden on the UE during actual resume execution
Solution Approach 2:
The system implements feedback mechanisms where the gNB monitors UE conditions and triggers pre-suspend configuration transmission when appropriate. This feedback loop ensures the UE only executes autonomous resume when network conditions are favorable, managing process complexity through intelligent network-controlled activation
Data Source
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AI summary
Provided is a method of obtaining public land mobile network (PLMN) information of a user equipment (UE), the method including receiving, by a UE access stratum (AS), a request for collecting the PLMN information from a UE non-AS (NAS), scanning at least one carrier in a frequency band supportable by the UE, determining, based on a result of the scanning, whether the at least one carrier is a carrier in an unlicensed frequency band, obtaining the PLMN information from at least one cell, based on a result of the determining, and providing, by the UE AS, the obtained PLMN information to the UE NAS.