VoIP IMS Registration Control for High-Priority RAT Reconnection
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Solution Overview
Problem
Existing configurations in 5G wireless communication systems do not address scenarios where a user equipment (UE) unnecessarily remains connected to a low priority radio access technology (RAT) after voice over Internet Protocol (IP) multimedia subsystem (IMS) becomes unavailable, leading to detrimental user experience due to disconnects and errors.
Innovation Solution
The UE synchronizes the IMS retry-timer with the RAT disable timer, determining whether the IMS failure is temporary or permanent to appropriately enable or disable the high priority RAT, and attempts IMS registration on all available cells before switching to a low priority RAT, leveraging interworking capabilities to re-enable the high priority RAT when conditions improve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE disables the high priority RAT due to voice over IMS failure, then voice service availability is improved, but connection stability deteriorates due to unnecessary remains on low priority RAT
Solution Approach 1:
The UE monitors voice over IMS availability and implements feedback mechanisms by attempting IMS registration on all available cells before switching RATs. When voice over IMS becomes available again, the UE re-attempts registration and can re-enable the high priority RAT, creating a closed-loop feedback system that prevents unnecessary connection instability
Solution Approach 2:
Before completely disabling the high priority RAT, the UE performs preliminary actions by attempting IMS registration on all available cells. This preliminary registration attempt allows the UE to detect if voice over IMS has become available again before making the final decision to switch to or remain on the low priority RAT, preventing unnecessary RAT switching
2Duration of action of moving object
If the UE switches to low priority RAT when voice over IMS is unavailable, then service continuity is improved, but user experience deteriorates due to disconnects and errors
Solution Approach 1:
The UE implements dynamic RAT selection by attempting IMS registration on all available cells and adapting its connection behavior based on registration outcomes. Rather than statically switching to low priority RAT, the UE dynamically evaluates available cells and maintains connections that provide the best user experience while ensuring service continuity
Solution Approach 2:
The UE changes connection parameters by attempting registration on multiple cells with different characteristics before finalizing the RAT selection. This parameter exploration allows the UE to find optimal connection settings that maintain service continuity while avoiding poor user experience associated with arbitrary low priority RAT switching
3Reliability
If the UE attempts IMS registration on all available cells, then registration success rate is improved, but signaling overhead increases
Solution Approach 1:
The UE performs self-service by autonomously attempting IMS registration on all available cells without requiring network assistance. This self-service approach improves registration success rate by independently exploring available cells, while the UE manages its own signaling overhead through efficient registration attempt management and failure handling
Data Source
AI summary
This disclosure describes a communication system associated with a radio access technology (RAT). The communication system includes an Internet protocol (IP) multimedia subsystem (IMS) server, and one or more processors configured to perform operations. The operations include receiving, from a user equipment device (UE) camped on the RAT, a request for IMS Packet Data Unit (PDU) establishment or IMS session initiation protocol (SIP) registration; sending to the UE a rejection message associated with the SIP registration or the IMS PDU establishment; receiving, from the UE, an IMS failure message that comprises an IMS failure cause; determining, based on the IMS failure message, whether the IMS failure cause is temporary or permanent; and responsive to determining that the IMS failure is temporary, temporarily disabling the RAT for the UE.