L1/L2 Triggered Mobility for Reduced Inter-gNB-CU Handover Interruptions
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Solution Overview
Problem
Existing 5G wireless communication systems face challenges in managing increased communication traffic and efficiently handling mobility between different base stations/gNB-CUs, particularly in inter-gNB-CU scenarios, leading to increased interruption times due to the need for layer 3-based handovers.
Innovation Solution
A method and apparatus for performing L1/L2 Triggered Mobility (LTM) that includes comparing identification information values of serving and target cells to determine PDCP reestablishment and L2 reset operations, enabling efficient inter-gNB-CU mobility with reduced interruption times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layer 3-based handovers are used for inter-gNB-CU mobility, then mobility between different base stations can be achieved, but interruption time increases
Solution Approach 1:
The patent segments the handover process into multiple stages: L1/L2-triggered mobility for rapid initial handover, followed by asynchronous data forwarding and PDCP reestablishment. This segmentation allows the critical mobility function to be decoupled from the data transfer function, enabling faster handover execution while maintaining data integrity through separate asynchronous data forwarding mechanisms.
Solution Approach 2:
The patent implements preliminary actions by pre-configuring L1/L2 parameters and mobility thresholds before handover is needed. The L1/L2 layer is prepared in advance to trigger mobility decisions autonomously when conditions are met, eliminating the need for higher-layer processing during the actual handover moment, thus reducing interruption time.
2Reliability
If PDCP reestablishment and L2 reset operations are performed during LTM, then data integrity can be maintained, but handover complexity increases
Solution Approach 1:
The patent introduces dynamic conditional execution of PDCP reestablishment and L2 reset operations based on comparison of identification information values. The system dynamically determines whether to perform these operations by comparing cell identity values, adapting the handover procedure complexity to the specific scenario rather than always executing the full sequence of operations.
Solution Approach 2:
The patent changes the state parameters of PDCP and L2 layers conditionally during LTM based on identification information comparison. By monitoring and comparing identification information values, the system selectively updates PDCP and L2 parameters only when necessary, maintaining data integrity while avoiding unnecessary operational complexity.
Data Source
AI summary
Disclosed are a method and apparatus for performing layer 1 (L1)/layer 2 (L2) triggered mobility (LTM) in a wireless communication system. The UE performs first comparison between a first identification information value of a serving cell and a second identification information value of a target cell to determine whether to reestablish a packet data convergence protocol (PDCP) in an LTM procedure. In addition, after performing the first comparison in the LTM procedure, the UE performs second comparison between a third identification information value of the serving cell and a fourth identification information value of the target cell to determine whether to reset the L2. Then, the UE performs an L2 reset operation based on the first comparison and the second comparison in the LTM procedure.