Cellular Network IMS Emergency Call Capability Broadcasting
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Solution Overview
Problem
Cellular wireless networks face challenges in ensuring timely and reliable emergency call capabilities, particularly in scenarios where a UE is in a limited service state or during network upgrades, as existing methods do not adequately inform the UE about the network's IMS emergency call support, leading to potential delays or failures in emergency call setups.
Innovation Solution
Broadcasting packet-switched emergency call capability information on a broadcast channel within the network, including details on network support, local regulations, and operator policies, allows the UE to determine IMS emergency call capability without requiring network signaling, enabling flexible and efficient emergency call handling even when the UE is in a limited service state or during differential network upgrades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the network uses traditional circuit-switched domain for emergency calls, then emergency calls can be handled reliably, but packet-switched networks cannot natively support emergency calls without additional mechanisms
Solution Approach 1:
The patent extracts the emergency call capability indication from the core network signaling and places it at the access node level. The access node independently indicates its packet-switched emergency call capability through system information broadcasting, separating the capability indication function from the core network's circuit-switched/fallback logic.
Solution Approach 2:
The access node acts as an intermediary between the packet core and the UE regarding emergency call capability information. It receives capability indications from the packet core and translates them into accessible system information for UEs, bridging the gap between packet-switched infrastructure and UE emergency call requirements.
2Productivity
If the core network is upgraded to support IMS emergency calls before base stations, then the packet core has emergency call capability, but UEs cannot make emergency calls because base stations do not support it yet
Solution Approach 1:
The access node performs preliminary action by pre-indicating its packet-switched emergency call capability through system information broadcasting before any UE attempts to make an emergency call. This allows UEs to assess capability in advance and avoid futile call attempts, improving both setup time and reliability during phased network upgrades.
Solution Approach 2:
The system implements feedback by having the access node continuously broadcast its emergency call capability status. UEs receive this feedback information and use it to make informed decisions about emergency call attempts, creating a closed-loop system that adapts to the current network state.
3Measurement precision
If the UE performs signaling procedures to determine network emergency call support, then the UE can verify capability, but UEs in limited service state cannot perform signaling and thus cannot determine capability
Solution Approach 1:
The access node provides self-service by autonomously broadcasting its packet-switched emergency call capability in system information. UEs can directly read this information without needing to engage in complex signaling procedures, making the capability detection process simple and accessible to all UEs including those in limited service state.
Solution Approach 2:
The capability indication is segmented into separate system information blocks that can be independently decoded by UEs. This segmentation allows UEs to extract only the emergency call capability information they need without processing entire signaling procedures, simplifying the operation while maintaining precision.
Data Source
AI summary
A method of operating a cellular wireless network comprises broadcasting information about Internet Multimedia Subsystem (IMS) emergency call capability of the network on a broadcast channel in a cell of the network. This information may in one method concern the IMS emergency call capability of a base station included in the network and in another method it may include IMS emergency call capability of a base station and the core network.