eCall-Only UE Inter-RAT Mobility and Detachment
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Solution Overview
Problem
Current eCall solutions lack comprehensive mobility management procedures during and after inter-Radio Access Technology (RAT) mobility, particularly for UEs in eCall-only mode, leading to issues such as incomplete detach procedures and unreachable states for PSAP calls post-eCall termination.
Innovation Solution
A method for supporting inter-RAT mobility in eCall-only mode involves establishing and releasing communication sessions, starting timers based on access changes, and performing eCall inactivity procedures, which include detaching from the wireless network and refraining from signaling in the absence of further eCalls or test/reconfiguration calls, ensuring proper network detachment and reduced unnecessary network loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE in eCall-only mode performs mobility management procedures during and after inter-RAT mobility, then the UE can maintain network connectivity and reachability, but the network is loaded with unnecessary mobility management procedures
Solution Approach 1:
The patent applies preliminary action by having the UE perform detach procedures in advance after inter-RAT mobility events. The UE is configured to execute detach procedures automatically following specific mobility conditions (such as handover between RATs or expiration of inactivity timers), thereby proactively managing network connectivity rather than reacting to network requests. This ensures the UE detaches appropriately after eCall events while maintaining reachability when needed, optimizing network resource utilization.
2Reliability
If the UE continues mobility management procedures for a limited duration after eCall termination, then the UE can be reached by the network for callback calls, but the UE remains on the network loading resources unnecessarily
Solution Approach 1:
The patent implements periodic action through the use of inactivity timers that periodically check and manage UE connectivity state. The network and UE monitor inactivity periods and automatically execute detach procedures after a predetermined duration without UE activity. This periodic monitoring and conditional detachment ensures the UE remains reachable during necessary periods while automatically releasing network resources after the eCall event and callback window have passed, optimizing the balance between reliability and resource consumption.
Data Source
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AI summary
Disclosed are techniques for supporting inter-RAT mobility of UEs in eCall-only mode. In an aspect, a UE establishes a communication session for an eCall or a test/reconfiguration call (702), releases the communication session for the eCall or test/reconfiguration call (704), starts a timer (706) based on at least one of release (708), by the UE, of a PS signaling connection for a UMTS access for the communication session, (710) expiration at the UE of a READY timer for GPRS, wherein the READY timer was started by the UE following a PS handover of the communication session from an LTE access to a GSM-GPRS access, (712) intersystem change by the UE from an LTE access to a GSM-GPRS access or a UMTS access, or (714) intersystem change by the UE from a GSM access or a UMTS access to an LTE access, and performs an eCall inactivity procedure when the timer expires (716).