PLMN Selection Timing Control in Roaming UEs
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Solution Overview
Problem
In a 5G roaming environment, it is challenging to control the timing of network selection by user equipment, which affects the prioritization of Public Land Mobile Networks (PLMNs) and can lead to disruptions during different types of calls, such as voice or data communications, and emergency calls.
Innovation Solution
The solution involves using NAS signaling to transmit priority PLMN lists and trigger information from the Home PLMN to the User Equipment (UE), allowing the UE to perform PLMN selection based on timer values and flags specific to each call type, ensuring optimal network selection timing without disrupting ongoing communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the user equipment automatically performs PLMN selection when SoR information is acquired, then the network selection is executed promptly, but it causes disruptions during ongoing communications such as voice or data calls
Solution Approach 1:
The patent applies dynamics by making the PLMN selection timing adaptive based on the current communication state. The network node determines whether to trigger PLMN selection dynamically depending on whether the UE is engaged in a call or data communication, allowing the system to flexibly adjust between immediate execution and delayed execution to maintain communication continuity while enabling timely network selection when appropriate.
2Productivity
If the user equipment performs PLMN selection immediately upon acquiring SoR information, then the prioritization is applied quickly, but it interrupts ongoing voice or data calls
Solution Approach 1:
The patent applies preliminary action by having the network node proactively determine the appropriate timing for PLMN selection based on the UE's current communication state before actually triggering the selection. The network node assesses whether the UE is in a call or data communication state and only triggers PLMN selection when it is safe to do so, preventing disruptions while ensuring timely network selection.
3Adaptability or versatility
If the user equipment allows PLMN selection during any state, then the network prioritization is flexible, but it causes interruptions during emergency calls and active communications
Solution Approach 1:
The patent applies local quality by differentiating the PLMN selection behavior based on the specific communication state of the UE. Instead of a uniform approach, the network node applies different rules: PLMN selection is triggered when the UE is in idle state, but suppressed when the UE is engaged in voice calls, data communications, or emergency calls. This localized adaptation ensures network selection flexibility where appropriate while protecting call integrity where critical.
Data Source
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AI summary
OBJECT To control a trigger of network selection by a user equipment in a roaming environment. SOLUTION MEANS A user equipment includes a receiving unit configured to receive, from a network node in a VPLMN (Visited Public land mobile network), information indicating a PLMN to be prioritized and information indicating a trigger of PLMN selection; and a control unit configured to execute the PLMN selection, based on the information indicating the PLMN to be prioritized and the information indicating the trigger of the PLMN selection.