AMF Registration Signaling for 4G-5G Handover Voice Updates
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Solution Overview
Problem
The frequent handovers between 4G and 5G networks result in increased signaling among core network nodes, including redundant registration and update messages to the unified data management node (UDM), leading to inefficiencies and potential loss of information.
Innovation Solution
The access and mobility management function (AMF) sends a registration message with an initial registration flag set to false and refrains from sending an update message to the UDM when the registration request is not initial, storing the imsVoPS indication and only sending an update message if the indication changes, thereby reducing redundant signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the AMF sends update messages to the UDM for each handover, then the voice capability information is updated, but redundant signaling occurs and network efficiency decreases
Solution Approach 1:
The AMF performs preliminary action by including the imsVoPS indication in the initial registration message sent to the UDM during the first handover from 4G to 5G. This preliminary inclusion ensures that the voice capability information is established upfront, eliminating the need for subsequent update messages during normal operation.
Solution Approach 2:
The system discards the redundant update messages that would otherwise be sent after the initial registration. By recovering and reusing the imsVoPS indication that was already provided in the initial registration message, the system avoids unnecessary signaling while maintaining the reliability of voice capability information.
2Loss of information
If the AMF sends registration messages with initial registration flag set to true, then the UDM knows it's an initial registration, but subsequent handovers require redundant update messages
Solution Approach 1:
The system dynamically adjusts the registration message content based on the handover context. During the initial registration from 4G to 5G, the AMF includes the imsVoPS indication and sets the initial registration flag to true. For subsequent handovers, the AMF refrains from sending update messages, creating a dynamic signaling approach that reduces complexity while maintaining information accuracy.
3Reliability
If the AMF includes imsVoPS indication in every registration message, then voice capability is consistently conveyed, but signaling overhead increases
Solution Approach 1:
The system applies local quality by selectively including the imsVoPS indication only in the initial registration message where it is most needed for establishing voice capability. Subsequent registration messages omit this parameter since the capability has already been established, reducing signaling overhead while maintaining reliable voice capability conveyance when required.
Data Source
AI summary
An access and mobility management function (AMF) configured to send a registration message with an initial registration flag set to false to a unified data management node (UDM) and refrain from sending an update message to the UDM is described herein. The AMF receives a registration request from a user equipment (UE) associated with a handover of the UE from a fourth generation (4G) network to a fifth generation (5G) network and determines that the registration request is not for an initial registration. In response to determining that the registration request is not for an initial registration, the AMF sends the registration message to the UDM with an initial registration flag set to false and refrains from sending the update message to the UDM.