Inter-Cell Mobility Triggering for Inter-Frequency L1/L2 Handover
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Solution Overview
Problem
Current network-controlled mobility mechanisms, particularly in L1/L2 based inter-cell mobility, fail to support inter-frequency scenarios due to the inability of terminals to perform L1 measurements on inter-frequency neighboring cells, leading to suboptimal cell selection and reduced network capacity.
Innovation Solution
A method and apparatus for inter-cell mobility that includes L1 and L2 based procedures, enabling terminals to perform measurements and report results on inter-frequency cells, allowing the network to trigger handovers to the best quality cell, using L1 or L2 signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If L1 measurement is used for inter-cell mobility triggering, then mobility delay and overhead are reduced, but inter-frequency scenarios cannot be supported because terminals cannot perform L1 measurement on inter-frequency cells
Solution Approach 1:
The patent segments the measurement process into two distinct parts: L1 measurement for intra-frequency cells (providing fast, low-overhead mobility) and L3 measurement for inter-frequency cells (enabling broader frequency support). This segmentation allows the system to leverage the advantages of both measurement types without requiring terminals to perform unsupported L1 measurements on inter-frequency cells.
Solution Approach 2:
The patent introduces L3 measurement as an intermediary mechanism that bridges the gap between the need for fast mobility (L1) and inter-frequency support requirements. The L3 measurement results serve as a trigger for L1/L2-based mobility procedures, enabling the system to handle inter-frequency scenarios while maintaining the performance benefits of L1-based mobility where applicable.
2Adaptability or versatility
If L3 measurement with RRC signaling is used for serving cell change, then inter-frequency scenarios are supported, but full L2 resetting is required resulting in longer delay and greater overhead
Solution Approach 1:
The patent performs L3 measurement in advance to identify suitable target cells for inter-frequency mobility. By pre-acquiring L3 measurement results and using them to trigger L1/L2-based procedures, the system prepares the mobility decision beforehand, enabling faster execution when the handover is actually initiated, thus reducing the overall perceived delay.
Solution Approach 2:
The patent implements a dynamic mobility triggering mechanism that adapts the measurement and handover procedure based on the frequency scenario. For intra-frequency cells, it uses L1 measurement with L1/L2-based triggering (fast path). For inter-frequency cells, it uses L3 measurement with appropriate triggering (standard path). This dynamic adaptation optimizes the balance between delay and support capability for different scenarios.
3Device complexity
If L1/L2 based mobility is implemented, then overhead and interruption duration are reduced, but the mechanism cannot trigger handover to inter-frequency cells with better quality
Solution Approach 1:
The patent creates a universal mobility triggering framework that can handle both intra-frequency and inter-frequency scenarios through a unified L1/L2-based procedure. The framework accepts multiple types of measurement results (L1 for intra-frequency, L3 for inter-frequency) as valid triggers for the same fast mobility procedure, making the system multi-functional without requiring separate handover mechanisms for different frequency scenarios.
Data Source
AI summary
A triggering apparatus for an inter-cell mobility procedure includes: a receiver configured to receive measurement-related information, the measurement-related information including one of the following: a layer 1 measurement result by performing layer 1 measurement on a frequency of an inter-frequency candidate target cell or on an inter-frequency candidate target cell by a terminal equipment, first indication information from a second network device based on a layer 3 measurement result by performing layer 3 measurement on a frequency of an inter-frequency candidate target cell or on an inter-frequency candidate target cell by the terminal equipment, or a layer 1 measurement result associated with a candidate target cell; and triggering processor circuitry configured to, based on the measurement-related information, trigger a layer 1 or layer 2 based inter-cell mobility procedure from a serving cell to a target cell.