Emergency Call Handover Across Wireless Networks
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Solution Overview
Problem
Current wireless communication systems face limitations in maintaining emergency calls when a user moves between coverage areas of different wireless networks, as handover is typically restricted to one network operator and may result in call dropouts.
Innovation Solution
The implementation of a method that enables handover of an emergency call from one network operator to another by using an Emergency Session Transfer Identifier (E-STI) to establish a continuous connection, allowing the call to be transferred from WiFi access to cellular access across different network operators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If handover is restricted to one network operator, then network management is simplified, but emergency call continuity is compromised when moving between different operator coverage areas
Solution Approach 1:
The patent introduces an Emergency Session Transfer Identifier (E-STI) as an intermediary mechanism that enables handover between different network operators. The E-STI acts as a mediator that carries essential call identification information across network boundaries, allowing the emergency call to be transferred from a first network operator to a second network operator without requiring complex inter-operator agreements or management systems.
2Reliability
If handover between different network operators is enabled, then emergency call continuity is improved, but system complexity increases
Solution Approach 1:
The patent segments the handover process into distinct, manageable components: (1) detection of impaired wireless coverage, (2) identification of alternative network access, (3) establishment of second call with E-STI, and (4) merging of calls. This segmentation allows each component to be implemented independently using existing network infrastructure, avoiding the need for a completely new complex handover system.
Solution Approach 2:
The E-STI mechanism is designed to be universally applicable across different network operators and access types (WiFi, cellular). The same E-STI structure and handover procedure can be used regardless of which network operator or access technology is involved, reducing the need for operator-specific implementations and lowering overall system complexity.
3Adaptability or versatility
If emergency call handover is supported across different operators, then service coverage is extended, but call setup time increases
Solution Approach 1:
The patent performs preliminary actions by pre-establishing the E-STI identifier during the initial emergency call setup. The E-STI is prepared in advance and stored, so when handover is needed, the identifier is already available for immediate use. This eliminates the need for time-consuming identifier generation or negotiation during the actual handover event, reducing call setup time despite cross-operator complexity.
Data Source
AI summary
A method is provided to enable handoff of an emergency services call between different network operators. A UE may establish a first call with a first network for a first network operator based on a first wireless access type, where the first call is an emergency services call to a PSAP. The UE may then determine impaired wireless coverage for the first wireless access type and unimpaired wireless coverage for a second wireless access type for a second network, where the second network is for a second network operator different to the first network operator. The UE may then establish a second call with the second network based on the second wireless access type, where the second call is a continuation of the first call to the PSAP. In embodiments, the first wireless access type is WiFi and the second wireless access type is cellular.