WiFi Emergency Call Routing via IMS Location Registration
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Solution Overview
Problem
Emergency calls placed over WiFi networks by mobile client stations often default to their home Public-Safety Answering Point (PSAP) rather than the nearest one, leading to potential delays and complications due to the lack of location information in WiFi connections.
Innovation Solution
Incorporating location information into the registration process with an IP Multimedia Subsystem (IMS) when performing emergency calls over WiFi, ensuring that emergency calls are routed to the nearest PSAP rather than the home PSAP, with a default mechanism for standard location-free calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If emergency calls are placed over WiFi networks without location information, then the calls can be made using available wireless infrastructure, but the calls are routed to the home PSAP rather than the nearest one, causing delays and complications
Solution Approach 1:
The patent performs IMS registration with location information before the emergency call is placed. The client station determines its location and includes it in the registration request to the IMS network, so that when an emergency call is initiated, the network already has the location data needed to route the call to the correct local PSAP, eliminating routing delays
Solution Approach 2:
The patent introduces the IMS (IP Multimedia Subsystem) as an intermediary between the WiFi network and the PSAP routing system. The IMS acts as a mediator that receives location information from the client station during registration and uses this information to intelligently route emergency calls to the appropriate local PSAP, rather than defaulting to the home PSAP
2Reliability
If location information is incorporated into the IMS registration process, then emergency calls can be routed to the nearest PSAP, but the registration process becomes more complex
Solution Approach 1:
The patent enhances the existing IMS registration mechanism to serve multiple functions: it not only establishes the client's network identity and connectivity but also captures and stores location information. This multi-functional approach allows the same registration process to simultaneously handle network authentication and location registration, avoiding the need for separate location setup procedures
Solution Approach 2:
The patent modifies the registration process by adding location information as an additional parameter in the registration request message. This parameter extension allows the system to convey location data through the existing registration signaling framework without fundamentally changing the registration architecture, thereby maintaining compatibility while improving functionality
Data Source
AI summary
A station that performs methods related to emergency calls. In one example, the station determines that a first connection to a cellular network is unavailable, the client station being associated with a home network having a home Public-Safety Answering Point (PSAP), the station disposed at a location outside the home network, the location having a remote PSAP. The station determines a second connection to a WiFi network is available, establishes the second connection to the WiFi network and performs an emergency call over the WiFi network. The emergency call being routed to the remote PSAP associated with the location. In another example, the station determines it is capable of performing an emergency call over a cellular network, receives a request to perform an emergency call, determines whether a circuit switched radio access technology (CS-RAT) is available and performs the emergency call over a WiFi network when the CS-RAT is unavailable.