IMS Emergency Call Routing via Proxy-CSCF Redirection
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Solution Overview
Problem
There is no effective measure to realize a connection to the most suitable network for emergency call services in 5G systems, as existing technologies lack mechanisms for exchanging capabilities between core network apparatuses and between terminals and IMS apparatuses for emergency call services.
Innovation Solution
A user equipment and communication control method that transmits IMS emergency call connection signals to a Proxy-CSCF, determines the appropriate core network for emergency call connections by receiving rejection or redirection messages, and prioritizes voice service and PDU session functions through the AMF and Proxy-CSCF to ensure optimal network connectivity for emergency calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a core network supports only voice service function, then voice service is provided, but emergency call service cannot be supported
Solution Approach 1:
The patent introduces a Proxy-CSCF as an intermediary element between the terminal and the core network. When a terminal needs emergency call service but the core network only supports voice service, the Proxy-CSCF mediates the connection by redirecting the emergency call request to an appropriate core network that supports emergency call functions, thus enabling emergency service support without requiring every core network to have full emergency call capabilities
Solution Approach 2:
The patent segments the core network into different types: voice service core networks and emergency call service core networks. By dividing the core network functionality, the system allows terminals to connect to voice-only core networks for regular calls while routing emergency calls to specialized core networks, thereby supporting emergency call services without complicating the configuration of all core networks
2Reliability
If capability exchange mechanisms are established between core network apparatuses and between terminal and IMS apparatus, then appropriate network connection for emergency calls is achieved, but system complexity increases
Solution Approach 1:
The patent implements preliminary action by having the terminal advertise its emergency call capability during the initial IMS registration procedure. The terminal includes capability information in the registration request message sent to the Proxy-CSCF, so that the network is预先 informed of the terminal's emergency call capability. This allows the Proxy-CSCF to make appropriate routing decisions later when emergency call services are needed, without requiring complex real-time capability negotiation
Solution Approach 2:
The patent establishes feedback mechanisms where the Proxy-CSCF receives capability information from the terminal during registration, stores this information, and uses it to determine appropriate core network routing decisions. The network also provides feedback to the terminal through redirection messages that indicate the selected core network supports emergency call services, ensuring reliable connection while managing system complexity through structured information exchange
Data Source
AI summary
In an IMS emergency call connection of a call which a user equipment cannot recognize as an emergency call, a user equipment transmits to an IMS an IMS emergency call connection signal of the call which the user equipment cannot recognize as the emergency call, and in a case that a reject or redirection message indicating an emergency call connection is received from the IMS, the user equipment determines whether to transmit the IMS emergency call connection signal again to a core network to which the user equipment is connected or whether to transmit the IMS emergency call connection signal again to another core network in the same PLMN. Accordingly, a user equipment, a core network apparatus, a control method to be performed by an IMS apparatus, and the like are provided for the user equipment to connect to a network suitable for an emergency call service in the 5th generation (5G) mobile communication system, which is a next-generation mobile communication system.