Location Server VoIP Emergency Call Routing
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Solution Overview
Problem
Existing wireless communication networks face challenges in routing emergency Voice-over-Internet Protocol (VoIP) calls, particularly for users without a service subscription or roaming agreements, as they struggle to accurately determine the appropriate Public Safety Answering Point (PSAP) for emergency services.
Innovation Solution
A location server and method that enable emergency VoIP calls by obtaining a position estimate for User Equipment (UE) and routing the call to a selected PSAP, even for users without a service subscription, using various location architectures and protocols such as SUPL, 3GPP control plane, and X.S0024, ensuring connectivity to both IP and PSTN capable PSAPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a user without service subscription or roaming agreement places an emergency VoIP call, then the call can be established, but the network cannot accurately determine the appropriate PSAP for routing
Solution Approach 1:
The patent introduces a location server as an intermediary component that the UE communicates with directly to obtain position estimates. This location server acts as a mediator between the UE and the network elements that need location information, enabling the system to function even when the UE has no service subscription or roaming agreement with the network. The location server retrieves location data using alternative methods (cell ID, GPS coordinates) that do not require traditional subscription-based access.
2Productivity
If the network obtains an interim position estimate to route the emergency call, then the call can be routed to a PSAP, but the position estimate accuracy may be insufficient for precise emergency response
Solution Approach 1:
The patent implements a two-stage positioning approach where an interim position estimate is obtained first to enable rapid call routing to the appropriate PSAP, and then a more accurate position estimate is obtained after call establishment. This preliminary action allows the system to prioritize speed in the critical initial routing phase while still achieving high accuracy later for precise emergency response. The interim estimate uses faster but less accurate methods (cell ID), while the subsequent estimate uses more accurate but slower methods (GPS coordinates).
Solution Approach 2:
The patent makes the positioning system dynamic by allowing the position estimate accuracy to evolve over time. The system starts with a quick, less accurate interim position estimate for immediate routing, then transitions to a more accurate position estimate once the call is established. This dynamic approach adapts the measurement precision to the operational phase, optimizing both response time and accuracy at different stages of the emergency call process.
3Measurement precision
If the UE performs positioning with the location server after call establishment, then the position estimate is updated for accurate emergency response, but the positioning process time is extended
Solution Approach 1:
The patent performs the critical routing action (obtaining interim position estimate) before the full positioning process completes. By securing the call routing to the appropriate PSAP using the interim estimate first, the system ensures that time-sensitive routing is handled immediately, while the more time-consuming accurate positioning can proceed in parallel or afterward without delaying the critical initial response.
Data Source
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AI summary
Techniques to support emergency voice-over-Internet Protocol (VoIP) calls are described. The techniques may be used for various 3GPP and 3GPP2 networks, various location architectures, and various types of User Equipment (UE). A UE communicates with a visited network to send a request to establish an emergency VoIP call. The UE interacts with a location server instructed by the visited network to obtain a first position estimate for the UE. The UE performs call setup via the visited network to establish the emergency VoIP call with a PSAP, which may be selected based on the first position estimate. The UE may thereafter perform positioning with the location server to obtain an updated position estimate for the UE, e.g., if requested by the PSAP.