Secondary Node Counter Rules for Monotonic Handover Updates
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Solution Overview
Problem
Existing communication systems face challenges in determining secondary node counters (sk-counter) for terminal devices during intra-SN and inter-SN handovers, leading to unnecessary updates and non-monotonic increments, especially in NR-NR Dual Connectivity scenarios.
Innovation Solution
A method for determining secondary node counters based on first information, including secondary node counter delta values and candidate cell grouping, to ensure monotonically increasing counters and avoid unnecessary updates, using rules for intra-SN and inter-SN handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary node counter is updated during intra-SN handover, then the security key can be recalculated, but the counter becomes non-monotonic and may be reused, compromising security
Solution Approach 1:
The patent applies local quality by differentiating the counter update behavior based on the handover type. For inter-SN handovers, the counter is incremented to ensure monotonicity and security. For intra-SN handovers, the counter is maintained without update, preserving its monotonic property. This localized differentiation resolves the contradiction by applying appropriate update strategies to different scenarios.
Solution Approach 2:
Instead of universally updating the counter during all handovers, the patent inverts the approach by selectively maintaining the counter in intra-SN handovers. This inversion of the conventional wisdom (that counters should always be updated) resolves the monotonicity issue while still ensuring security through targeted updates only when necessary.
2Stability of the object's composition
If the secondary node counter is not updated during intra-SN handover, then counter monotonicity is preserved, but the terminal cannot distinguish between intra-SN and inter-SN handovers
Solution Approach 1:
The patent introduces an intermediary mechanism through the Master Node that provides handover type information to the terminal device. This intermediary allows the terminal to distinguish between intra-SN and inter-SN handovers without requiring counter updates in intra-SN scenarios, thus maintaining monotonicity while enabling proper handover type identification through network-assisted signaling.
3Adaptability or versatility
If candidate cell configurations include sk-counter configuration, then the terminal can determine the counter for selective activation, but the complexity of configuration management increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring candidate cell grouping information and sk-counter delta values at the network side before handover occurs. The terminal stores these pre-configured parameters and uses them automatically during handover decision-making, eliminating the need for complex real-time configuration management while enabling versatile selective activation across multiple candidate cells.
Data Source
AI summary
A method for determining the secondary node counter includes determining the secondary node counter based on first information. Through the technical solution of the present application, the terminal device can avoid unnecessary updates to the secondary node counter, and/or, when an update to the secondary node counter is required, the secondary node counter is not reused and/or the secondary node counter monotonically increases.