Multi-LRF Emergency Call Location Continuity via Signal Tunneling
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Solution Overview
Problem
Existing 3GPP networks face challenges in maintaining emergency location services continuity during handovers across multiple Location Retrieval Function (LRF) providers, particularly in IMS emergency calls, due to the lack of signal tunneling mechanisms and decoupled IMS and signaling domains, leading to potential service disruptions and unsupported Public Service Access Points (PSAPs).
Innovation Solution
A network device and method for ensuring voice call continuity during handovers by routing an emergency services routing key (ESRK) or emergency services query key (ESQK) from a source server to a target server in a multi-LRF environment, allowing seamless handover of IMS emergency calls between different emergency services networks, and maintaining continuous location support for Public Service Access Points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple LRF providers are deployed for emergency location services, then service reliability and load balancing are improved, but location continuity during handovers deteriorates due to lack of signal tunneling mechanisms
Solution Approach 1:
The patent introduces an intermediary mechanism (signal tunneling through source and target servers) that enables location information to be seamlessly transferred between multiple LRF providers during handovers. This intermediary approach allows the system to maintain location continuity despite the distributed multi-provider architecture, resolving the contradiction between service reliability improvement and location information loss.
2Adaptability or versatility
If IMS emergency calls are handover between different emergency services networks, then network flexibility and adaptability are improved, but service disruption occurs due to decoupled IMS and signaling domains
Solution Approach 1:
The patent implements preliminary action by pre-establishing signal tunneling paths and maintaining contextual information in source and target servers before handover occurs. This allows the system to rapidly execute handovers between different emergency services networks while maintaining service continuity, resolving the contradiction between network flexibility and service reliability.
3Productivity
If multiple LRFs are used for emergency location services, then load balancing is improved, but device complexity increases due to multiple servers and routing mechanisms
Solution Approach 1:
The patent applies universality by designing source and target servers with multi-functional capabilities that handle both normal operations and handover signaling tunneling. This universal design allows the same infrastructure to support multiple LRFs for load balancing while managing complexity through standardized, multi-purpose components rather than specialized dedicated systems.
Data Source
AI summary
An IMS emergency call is reliably handed off within the PS domain or from the PS domain to the CS domain, by providing continuous support of location of a user device on behalf of a PSAP. The invention provides for handover of an IMS emergency call with EPS/GPRS access in a multi-LRF environment. Emergency location services for CS based emergency and/or IMS based emergency location services are often provided by multiple emergency location service providers. The information element that is critical for supporting Location Continuity in Multi-LRF environment can be either the assigned ESQK or the Serving LRF address. ESQK is assigned by the Serving LRF during IMS emergency call setup, and is used to uniquely identify the emergency service provider that operates the serving LRF. A simpler implementation uses the Serving LRF's address to identify the Serving LRF during and after the handover (PS-PS or PS-CS).