Emergency Call Routing Over WLAN via ePDG Selection
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Solution Overview
Problem
Current 3GPP systems do not support emergency services over Wireless Local Area Networks (WLAN) such as Wi-Fi, leading to issues in selecting an appropriate evolved packet data gateway (ePDG) for emergency calls, especially for roaming users, which can result in incorrect or inappropriate ePDG selection and failure to establish emergency connections.
Innovation Solution
A method and apparatus that enable user equipment (UE) to initiate emergency calls over non-cellular technologies like Wi-Fi by creating an identifier with emergency indication information, transmitting location information, and selecting an appropriate ePDG capable of supporting emergency services, ensuring the ePDG is located in the visiting public land mobile network (VPLMN) for proper routing of IMS emergency calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DNS mechanisms are used for ePDG selection, then the system is simple and easy to operate, but emergency services cannot be supported over WLAN
Solution Approach 1:
The system performs preliminary actions by determining whether an emergency call is to be initiated before proceeding with ePDG selection. This early determination allows the system to prepare appropriate identification information and select suitable ePDGs in advance, ensuring emergency services can be properly supported without compromising system simplicity during normal operations
Solution Approach 2:
The invention changes the selection parameters by introducing emergency indication information into the identification created for ePDG selection. When an emergency call is detected, the system modifies the identification to include specific emergency indicators, which then directs the selection process to choose ePDGs capable of handling emergency services, thereby enabling emergency support through parameter modification rather than structural complexity
2Measurement precision
If ePDG selection is not controlled in VPLMN, then the selection process is simpler, but incorrect ePDG selection occurs for roaming users
Solution Approach 1:
The system applies local quality by implementing location-aware ePDG selection that adapts to the user's roaming status. When a roaming user initiates an emergency call, the system identifies the VPLMN and selects ePDGs specifically within that local network context. This ensures accurate ePDG selection for roaming users by tailoring the selection criteria to the local network environment rather than using a uniform approach
Solution Approach 2:
The invention incorporates feedback mechanisms by using location information and roaming status to inform the ePDG selection process. The system receives feedback about the user's current network context (whether roaming, which VPLMN is active) and uses this information to adjust the ePDG selection accordingly, ensuring that the selected ePDG is appropriate for the user's location and capability to support emergency services
3Reliability
If emergency calls are initiated over WLAN without proper ePDG selection, then connectivity is faster, but emergency service routing fails
Solution Approach 1:
The system performs preliminary determination of whether an emergency call is to be initiated before the actual call setup. This early detection allows the system to prepare emergency indication information and identify suitable ePDGs in advance, so that when the emergency call is actually initiated over WLAN, the routing is already optimized and can proceed without time-consuming selection delays
Solution Approach 2:
The invention modifies the identification parameters to include emergency indication information, which fundamentally changes how ePDG selection is performed. By embedding emergency indicators in the identification, the system can quickly match the call with appropriate ePDGs that support emergency services, enabling fast WLAN connectivity while ensuring correct emergency service routing through parameter-based differentiation
Data Source
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AI summary
Methods, systems, and devices are described for wireless communication to enable a UE to establish emergency services (e.g., IMS emergency calls) over WLAN (e.g., Wi-Fi) in 3GPP networks. Such mechanisms may help ensure that an ePDG capable of supporting emergency services is selected. Further, such mechanisms may help ensure that an appropriately located ePDG is selected. For example, the selected ePDG may be located in the visiting public land mobile network (VPLMN) for a roaming UE so that IMS emergency calls are routed appropriately. Selection of the ePDG may be under control of the network with which the UE is establishing connectivity for the emergency call, namely the VPLMN, as opposed to the home PLMN (HPLMN), for example. Such mechanisms may rely on knowledge that the connectivity being established is for emergency services, as well as other information regarding the UE, such as a current location of the UE.