Voice Call Continuity for Wireless Emergency Calls
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Solution Overview
Problem
Current solutions for Voice Call Continuity (VCC) in wireless emergency calls face challenges in distinguishing between new emergency calls and domain transfers, conveying VCC support, and efficiently routing calls between circuit-switched and IP Multimedia Subsystem (IMS) networks, particularly in visited networks, which can lead to delays and inability to maintain call continuity.
Innovation Solution
The proposed solution extends the Service Category parameter in Emergency Setup messages to indicate VCC support and distinguishes between new emergency calls and domain transfers by using multiple SCCP E.164 addresses for GMLC queries and providing modified VDN and VDI for domain transfer requests, allowing for seamless call continuity and reduced resource allocation in emergency scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VCC support is added to distinguish between new emergency calls and domain transfers, then call continuity reliability is improved, but message parameter complexity increases
Solution Approach 1:
The Service Category parameter is segmented into multiple bits, with specific bits allocated to indicate VCC support and call type differentiation. This allows the complex differentiation function to be distributed across multiple parameter bits rather than requiring a single complex field.
Solution Approach 2:
The Service Category parameter is made multi-functional by using it to simultaneously indicate both VCC support status and call type (new call vs. domain transfer). This reduces the need for separate dedicated parameters while maintaining the necessary differentiation capabilities.
2Measurement precision
If multiple SCCP E.164 addresses are used for GMLC queries to distinguish call types, then call routing accuracy is improved, but network configuration complexity increases
Solution Approach 1:
The GMLC addressing is segmented into multiple SCCP E.164 addresses, with each address corresponding to specific call types or network conditions. This segmentation allows accurate routing differentiation while distributing the configuration across multiple standardized address fields.
3Productivity
If modified VDN and VDI are provided for domain transfer requests, then domain transfer efficiency is improved, but signaling message complexity increases
Solution Approach 1:
The modified VDN and VDI are prepared and provided in advance during the domain transfer setup phase. This preliminary provision of transfer-specific parameters eliminates the need for complex real-time negotiation and reduces signaling overhead during the actual transfer execution.
Data Source
AI summary
Apparatus and methods to support Voice Call Continuity (VCC) for emergency calls in a wireless access environment are operable to receive, at a serving domain, a message containing emergency and domain transfer information from a user equipment (UE). The apparatus and methods are further operable to determine a need for emergency call origination or domain transfer based on the emergency and domain transfer information. Additionally, the apparatus and methods are operable to perform the emergency call origination or the domain transfer based on the determining.