Emergency Voice Call Fallback After Wireless System Errors
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Solution Overview
Problem
Existing wireless systems often deploy without direct support for emergency voice calls, and when errors occur during the fallback procedure, causing delays or failures in establishing a connection.
Innovation Solution
Implementing a wireless device with a processor that can connect to a first wireless system, determine that an error has occurred, and select a second wireless system based on the determination that the error has occurred, and connect to the second wireless system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wireless device attempts to establish an emergency voice call through the first wireless system, then the emergency call can be initiated, but if an error occurs during the fallback procedure, the connection establishment is delayed or fails
Solution Approach 1:
The wireless device performs preliminary error detection during the fallback procedure by monitoring for specific error conditions (e.g., T310 expiry, RRC connection release). When errors are detected, the device proactively selects an alternative wireless system before the call establishment fails, preventing delays and ensuring reliable emergency call connectivity.
2Reliability
If the wireless device implements automatic error detection and wireless system selection, then emergency call reliability is improved, but the device complexity increases
Solution Approach 1:
The wireless device autonomously monitors its own connection status, detects errors in the fallback procedure, and automatically selects alternative wireless systems without requiring external intervention. This self-service approach improves emergency call reliability while keeping the error handling mechanism relatively simple by leveraging existing device capabilities.
3Reliability
If the wireless device monitors for errors during the fallback procedure, then connection reliability is improved, but the processing overhead and complexity increase
Solution Approach 1:
The wireless device implements a feedback mechanism by monitoring connection status indicators (e.g., T310 timer expiry, RRC connection release messages) during the fallback procedure. When error conditions are detected through this feedback, the device triggers automatic wireless system selection, ensuring reliable emergency call connectivity with a relatively simple monitoring approach.
Data Source
AI summary
A technique for establishing a voice call including receiving an indication that the first wireless system supports emergency service fallback, receiving an indication to establish an emergency voice call, transmitting an emergency service request to the first wireless system, determining that an unexpected error has occurred, selecting a second wireless system based on the determination that the unexpected error has occurred, and connecting to the second wireless system to complete the emergency voice call. Additionally, a technique for cancelling a voice call including receiving an indication that the first wireless system supports emergency service fallback, receiving an indication to establish an emergency voice call, transmitting an emergency service request to the first wireless system, receiving an indication to cancel the emergency voice call, and cancelling a connection to a second wireless system.