UE PLMN Prioritization for Manipulated SoR and VoPS Gaps
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Solution Overview
Problem
Current 3GPP standards fail to address scenarios where a roaming PLMN indicates non-support of voice over packet switching (VoPS) and a manipulated or missing steering of roaming (SoR) container, leading to incorrect UE parameter updates and inefficient network selection.
Innovation Solution
A user equipment (UE) processor determines if a roaming PLMN supports VoPS and if an unmanipulated SoR container is received, adding it to a low priority list if not, and searches for higher priority PLMNs with 5G RAT support before disabling 5G services.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE follows current 3GPP standards for HPLMN parameter updates during roaming, then the UE parameters are updated based on network provider policies, but the UE parameters may not be updated in the correct manner when the roaming PLMN manipulates or omits the SoR container
Solution Approach 1:
The UE implements a feedback mechanism by detecting whether the SoR container is present and unmanipulated in the Registration Accept message. Based on this detection, the UE adjusts its behavior: if the SoR container is manipulated or missing, the UE adds the PLMN to a block list and disables 5G NR services, thereby correcting the parameter update process and preventing incorrect roaming parameter application.
Solution Approach 2:
The UE performs preliminary detection of the SoR container status before applying parameter updates. By checking for the presence and integrity of the SoR container in advance, the UE prevents incorrect parameter updates from being applied, ensuring that only valid and unmanipulated parameter sets are used for roaming configuration.
2Ease of operation
If the UE registers on a roaming PLMN without proper VoPS support detection, then registration is simplified, but voice services may be unavailable in N1 mode
Solution Approach 1:
The UE implements feedback by detecting the VoPS indication in the Registration Accept message. Based on this feedback, the UE determines whether to enable 5G NR services: if VoPS is not supported, the UE blocks 5G NR services and relies on alternative voice services, ensuring voice availability while maintaining registration simplicity.
Solution Approach 2:
The UE changes its service parameter configuration based on VoPS support detection. When VoPS is not supported, the UE modifies its service parameters by disabling 5G NR voice services and adjusting to use alternative voice service modes, thereby maintaining ease of registration while ensuring voice service reliability.
3Reliability
If the UE immediately disables 5G NR services when SoR container is manipulated, then incorrect parameter updates are prevented, but network selection efficiency is reduced
Solution Approach 1:
The UE performs preliminary detection of SoR container manipulation before finalizing network selection. By detecting and blocking manipulated PLMNs in advance, the UE prevents incorrect parameter updates while maintaining efficient network selection through the block list mechanism, which allows rapid identification and exclusion of unsuitable networks.
Data Source
AI summary
A user equipment (UE) transmits a registration request message to a first public land mobile network (PLMN), wherein the first PLMN is a roaming PLMN, receives a registration accept message from the first PLMN, determines that the registration accept message includes a manipulated steering of roaming (SoR) container or does not include a SoR container, wherein the SoR container is configured by a home PLMN (HPLMN) of the UE and transmitted to the first PLMN from the HPLMN, determines that the registration accept message includes an indication that the first PLMN does not support voice over packet switching (VoPS) and adds the first PLMN to a first list of PLMNs in which voice service is not possible in an N1 mode.