IMS Emergency Call Redirection via Alternative Core Network
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Solution Overview
Problem
Current wireless communication networks face challenges in establishing reliable emergency voice calls, especially when users are roaming or accessing data-only networks, leading to potential failures in connecting with local Public Safety Answering Points (PSAPs) due to lack of local Voice Service Providers (VSP) and limited support for alternative location solutions.
Innovation Solution
A method and apparatus that allow user equipment to transmit an emergency call request to a first serving core network and establish the call with a second serving core network, determined by the first network as an alternative, enabling emergency call establishment even when the user is outside the initial network's emergency serving area or lacks voice call capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a user equipment transmits an emergency call request to a first serving core network while roaming or accessing a data-only network, then the user can initiate an emergency call, but the first serving core network may not be able to establish the call with a local PSAP due to lack of local VSP or voice call capability
Solution Approach 1:
The patent introduces a second serving core network as an intermediary when the first serving core network cannot establish the emergency call. The first network determines it lacks capability and redirects to a second network that has the necessary local VSP and voice call capabilities, allowing the emergency call to be established through this intermediary network
Solution Approach 2:
The patent changes the serving core network parameter from the first network to a second network when the initial network proves inadequate. This parameter change allows the system to adapt to different network conditions and capabilities, ensuring the emergency call can be established with appropriate local services
2Reliability
If the first serving core network rejects the IMS emergency call attempt, then the user equipment must search for alternative networks, but this search process is unreliable and time-consuming
Solution Approach 1:
The first serving core network performs preliminary determination of its own capability to establish emergency calls before the user equipment attempts the call. By proactively identifying its limitations and redirecting to a suitable second network in advance, the system avoids the time loss associated with failed call attempts and subsequent network searching by the user equipment
3Reliability
If the first serving core network determines an alternative serving core network, then the emergency call can be established with a suitable network, but this requires additional network determination and redirection steps
Solution Approach 1:
The first serving core network autonomously determines its own capability to establish emergency calls and self-initiates the redirection to a second serving core network when needed. This self-service approach eliminates the need for complex user equipment-based network searching and trial attempts, as the network itself handles the determination and redirection process
Data Source
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AI summary
Apparatus and methods of establishing an emergency voice call include user equipment transmitting, and a first serving core network receiving, a request for an emergency call via a wireless access network. The apparatus and methods further include a determination by the first serving core network of an alternative serving core network. In some aspects, the determination may be made based on a user equipment location from a location retrieval function, which may obtain such information from other network components or from the user equipment. In other aspects, the determination may be based on lack of capability or lack of capacity. Further, the apparatus and methods also include establishment of the emergency call with a second serving core network different from the serving core network based on the determination.