L1/L2 Triggered Mobility Reporting for Low-Latency Cell Switching
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Solution Overview
Problem
Current mobility mechanisms in 5G wireless communication systems, such as L3 measurements and RRC signaling, result in high latency and service interruption during cell changes, necessitating a more efficient mobility mechanism with reduced interruption time.
Innovation Solution
Implementing L1/L2 Triggered Mobility (LTM) with event-based CSI reporting, where UEs receive RRCReconfiguration messages for LTM configurations, evaluate trigger events, initiate measurement reporting, and transmit MAC CEs for periodic reporting to facilitate seamless cell switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If L3 measurements and RRC signaling are used for cell switching, then mobility management is achieved, but latency and service interruption increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring LTM parameters, LTM candidate cell configurations, and measurement resources before mobility is needed. The UE performs L1 measurements and evaluates LTM events in advance, preparing measurement reports that can be quickly activated when cell switching is required, thus reducing latency and service interruption during actual mobility events.
2Reliability
If complete L2 and L1 resets are performed during serving cell change, then reconfiguration is achieved, but overhead and interruption time increase
Solution Approach 1:
The patent segments the mobility reconfiguration process into independent LTM measurement reporting procedures that operate separately from complete L2/L1 resets. By dividing the reconfiguration into modular LTM-specific steps (measurement configuration, event evaluation, report transmission), the system achieves necessary reconfiguration without the overhead and interruption of full protocol stack resets.
Solution Approach 2:
The patent introduces dynamic LTM event-based triggering that adapts the measurement reporting procedure to actual mobility conditions. Instead of static complete resets, the system dynamically activates LTM reporting only when LTM events are triggered, allowing flexible, condition-based reconfiguration that reduces overhead and interruption time while maintaining reliability.
Data Source
AI summary
A method for event-based CSI reporting is provided. The method includes receiving from base station RRCReconfiguration message that comprises various parameters for LTM such as LTM event configurations; evaluating whether LTM event is triggered; initiating LTM measurement reporting procedure if LTM event is triggered; transmitting LTM MR MAC CE for initial reporting; and transmitting periodically LTM MR MAC CEs for subsequent reporting. Subsequent reporting is performed periodically.