IMS PDN/PDU Fallback for Faster Emergency Call Reattempts
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Solution Overview
Problem
Existing systems face delays and inefficiencies in establishing emergency calls over cellular networks due to domain reselection failures when initial attempts through emergency PDN/EPDU networks fail, leading to potential disconnection and reduced reliability.
Innovation Solution
Prioritizing the use of IMS PDN/PDU sessions over domain reselection by attempting emergency calls first through an EPDN/EPDU and then IMS PDN/PDU, with network policies guiding reattempts based on failure scenarios, ensuring faster and more reliable emergency call connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs domain reselection when emergency call fails over EPDN/EPDU, then the UE attempts to use a different network, but the call connection is delayed and may fail if the other network is unavailable
Solution Approach 1:
The system pre-establishes an IMS PDN/PDU session before the emergency call attempt fails. When the EPDN/EPDU call fails, the UE can immediately use the pre-established IMS PDN/PDU session without performing time-consuming domain reselection, thus reducing call setup time while maintaining reliability
Solution Approach 2:
The IMS PDN/PDU session acts as an intermediary fallback path. Instead of directly switching networks through domain reselection, the system uses the IMS PDN/PDU session as a mediating communication path that can handle emergency calls when the primary EPDN/EPDU path fails, avoiding the delays and failures associated with domain reselection
2Reliability
If the UE attempts emergency call through EPDN/EPDU first, then the call may connect successfully, but if it fails the UE must perform domain reselection which causes delays
Solution Approach 1:
The IMS PDN/PDU session is established in advance before the emergency call attempt. This preliminary action ensures that when the primary EPDN/EPDU path fails, the UE can immediately switch to the pre-configured IMS PDN/PDU session without the productivity loss associated with domain reselection procedures
Solution Approach 2:
The system implements dynamic call routing that adapts based on network conditions. The UE can dynamically switch between EPDN/EPDU and IMS PDN/PDU paths without static domain reselection, allowing flexible and rapid adaptation to network availability while maintaining high call establishment speed
Data Source
AI summary
Solutions for placing an emergency call over a wireless network improve speed and reliability by prioritizing using an internet protocol (IP) multimedia subsystem (IMS) packet data network (PDN) or protocol data unit (PDU) network (PDN/PDU) over domain reselection when a call attempt fails over an emergency PDN/PDU (EPDN/EPDU). Examples include establishing an IMS PDN/PDU session for a user equipment (UE) over a wireless network; attempting, by the UE, an emergency call using an EPDN/EPDU over the wireless network; and based on at least a failure of the emergency call over the EPDN/EPDU, reattempting the emergency call using the IMS PDN/PDU over the wireless network. Based on at least a failure of the emergency call over the IMS PDN/PDU, the UE performs domain reselection and reattempts the emergency call using a second wireless network. In some examples, wireless networks transmit a network policy for handling the emergency call to the UE.