P-CSCF Urgency Indication for VoLTE Call Interruption
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Solution Overview
Problem
Current mechanisms for assigning a new Proxy-Call Session Control Function (P-CSCF) address to User Equipment (UE) in communication systems do not provide urgency handling for ongoing calls, leading to unmanageable call interruptions during P-CSCF failures or maintenance scenarios.
Innovation Solution
Incorporating a P-CSCF urgency indication and timer in the bearer modification message sent from the Core Network to the UE, allowing the UE to decide whether to initiate a new IMS registration directly or after completing the ongoing call, based on the urgency level and waiting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network sends a new P-CSCF address in a bearer modification message without urgency indication, then the P-CSCF can be changed for maintenance or failure reasons, but the UE cannot determine whether to interrupt ongoing calls or wait, leading to unnecessary call interruptions in maintenance scenarios
Solution Approach 1:
The P-CSCF address assignment process is segmented into two independent components: the P-CSCF address itself and the urgency indication. This segmentation allows the UE to receive both pieces of information separately and make informed decisions based on the urgency level, resolving the contradiction between reliable P-CSCF assignment and simple UE operation.
Solution Approach 2:
The network performs preliminary action by including the urgency indication along with the P-CSCF address assignment. This preliminary information provision enables the UE to pre-determine its next actions (interrupt or wait) without having to interpret complex scenarios, thus maintaining both reliability and operational simplicity.
2Speed
If the UE directly initiates new IMS registration upon receiving new P-CSCF address, then the P-CSCF change is executed promptly, but ongoing calls are unnecessarily interrupted during maintenance scenarios
Solution Approach 1:
The UE's response behavior is made dynamic based on the urgency indication received. When urgency is high (P-CSCF failure), the UE quickly interrupts calls and reregisters. When urgency is low (maintenance), the UE waits for call completion. This dynamic adaptation resolves the contradiction between execution speed and harm prevention.
Solution Approach 2:
The urgency indication acts as a parameter that changes the UE's behavioral state. By receiving different urgency values, the UE adjusts its timing and action parameters accordingly, enabling fast response when needed and delayed response when harmful, thus resolving the speed-harm contradiction.
3Object-generated harmful factors
If the UE waits for ongoing call to complete before initiating new IMS registration, then call interruptions are minimized, but the P-CSCF change is delayed which may be problematic in failure scenarios
Solution Approach 1:
The urgency indication provides feedback from the network to the UE about the criticality of the P-CSCF change. This feedback mechanism enables the UE to adjust its waiting behavior appropriately - waiting when urgency is low (maintenance) and not waiting when urgency is high (failure), thus resolving the contradiction between minimizing interruptions and ensuring reliability.
Data Source
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AI summary
A communication method in a communication system, wherein the communication system comprises a User Equipment, UE, a Core Network and an IP Multimedia Subsystem, IMS, the method comprising: initiating, from the UE, a registration towards the IMS; engaging in a communication between the UE and the IMS; signaling, from the Core Network to the UE, a P-CSCF address in a bearer modification message, wherein the bearer modification message includes a P-CSCF urgency indication; receiving, at the UE, the P-CSCF address and the P-CSCF urgency indication, wherein if the P-CSCF urgency indication indicates the highest possible urgency, directly initiating, by the UE, a new IMS registration based on the received P-CSCF address and interrupting the communication, wherein if the P-CSCF urgency indication indicates lower urgency and waiting time X, waiting, at the UE, X time for the communication to end and initiating a new IMS registration to the P-CSCF address and interrupting the communication if the communication is still ongoing.