UE Session Key Derivation for Low-Latency Inter-gNB Cell Switching
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Solution Overview
Problem
Existing 5G wireless communication systems face challenges in efficiently managing inter-gNB Layer 2 mobility, particularly in scenarios requiring cell switches between different base stations, which often necessitate RRC reconfiguration and longer latency, overhead, and interruption times, and lack support for seamless security key updates.
Innovation Solution
A user equipment (UE) is equipped with circuitry to store parameter pairs including a next hop (NH) and NH chaining counter (NCC) for each candidate base station, enabling it to derive a session key using a parameter pair associated with a target base station for secure communication without RRC reconfiguration during inter-gNB cell switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RRC reconfiguration is used for inter-gNB cell switches, then communication security is maintained, but latency and overhead increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring candidate base stations with parameter pairs (NH, NCC) before actual cell switch occurs. The UE stores these parameter pairs in advance, so when a cell switch is needed, the security key can be derived immediately using the pre-stored parameters without requiring RRC reconfiguration, thus reducing latency while maintaining security.
Solution Approach 2:
The patent uses copying by creating a list of parameter pairs that replicates the security context information across multiple candidate base stations. Instead of transferring the entire security context during handover, only the necessary parameter pairs (NH, NCC) are copied and stored in the UE, enabling fast key derivation without full RRC reconfiguration.
2Reliability
If RRC reconfiguration is used for inter-gNB cell switches, then security key updates are performed, but overhead and interruption time increase
Solution Approach 1:
The patent extracts only the essential security parameters (NH, NCC) from the complete security context and separates them as independent parameter pairs that can be stored and reused. This extraction allows the UE to derive security keys for candidate base stations without transferring the entire security context, reducing overhead during cell switches.
Solution Approach 2:
The patent segments the security context into discrete parameter pairs (NH, NCC) that can be independently stored and managed for each candidate base station. This segmentation enables the UE to selectively use only the necessary parameters for key derivation, avoiding the complexity of full RRC reconfiguration while maintaining secure key updates.
3Loss of time
If parameter pairs are stored for each candidate base station, then cell switch latency is reduced, but device memory requirements increase
Solution Approach 1:
The patent applies partial action by storing only the essential parameter pairs (NH, NCC) rather than the complete security context for each candidate base station. This partial storage approach provides sufficient information for key derivation and cell switch operations while minimizing the memory footprint, avoiding excessive storage requirements.
Data Source
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AI summary
Provided is a user equipment, user equipment, UE, comprising circuitry which, in operation, stores a list of parameter pairs, wherein each parameter pair includes a next hop, NH, parameter and an NH chaining counter, NCC, and each parameter pair is associated with one of at least one candidate base station. The US further comprises a transceiver which, in operation, receives a cell switch command including an indication of a target cell of a target base station, the target base station being one of the at least one candidate base station. The circuitry which, in operation, derives a session key using a parameter pair associated with a serving base station or a parameter pair associated with the target base station; and uses the derived session key for communication with the target base station.