UE Timer Expiration Handling for 5G Emergency Service Fallback
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Solution Overview
Problem
Existing 5G communication systems lack effective mechanisms for handling timer expiration during emergency service fallback (ESFB) procedures, which can lead to failure of emergency sessions.
Innovation Solution
Implementing specific timer (T3517) expiration handling mechanisms in user equipment (UE) that consider emergency service fallback requirements, allowing the UE to select alternative radio cells connected to the 5G core network or evolved packet core to establish emergency sessions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard service request procedures are used in 5G networks, then normal communication services can be established, but emergency service sessions may fail when timer expiration occurs
Solution Approach 1:
The patent applies preliminary action by detecting timer expiration events (T3517, T3518, T3519) before emergency service sessions fail completely. The UE proactively identifies when these timers expire and triggers alternative establishment procedures, preventing session failure rather than reacting after failure occurs. This early detection and intervention mechanism ensures emergency services can be established through alternative paths before standard procedures fail.
Solution Approach 2:
The patent applies parameter changes by modifying the service request message parameters when timer expiration is detected. Specifically, the UE changes the cause value in the service request message to indicate timer expiration and alters the establishment procedure parameters to use alternative radio access technologies or core networks. This parameter modification enables the network to recognize the abnormal condition and route the emergency service request through appropriate alternative paths.
2Reliability
If alternative radio cells are selected for emergency services, then session establishment reliability improves, but the time required for cell selection and connection increases
Solution Approach 1:
The patent applies preliminary action by pre-identifying alternative radio cells and networks that can support emergency services. The UE maintains information about alternative cells connected to 5G core networks or evolved packet cores before they are needed. When timer expiration occurs, the UE can immediately switch to these pre-identified alternatives rather than performing extensive cell search procedures, significantly reducing the time penalty while maintaining high reliability.
Solution Approach 2:
The patent applies dynamics by enabling the UE to dynamically switch between standard and alternative service request procedures based on real-time conditions. The system can adaptively select which radio cell or core network to use for emergency services, changing the communication path dynamically in response to timer expiration events. This dynamic capability allows the system to optimize between speed and reliability by choosing the fastest available alternative path.
Data Source
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AI summary
An apparatus comprising means for performing: determining an expiration of a service request timer generated in association with a service request message from the apparatus; and handling the expiration of the service request timer based on a determination of a service type of the service request message.