Dual VLR Issue Resolution via HSS Triggering
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Solution Overview
Problem
The dual Visitor Location Register (VLR) issue in LTE networks, where both VLRs mistakenly register a User Equipment (UE) on their node, leading to failed CS calls and SMS paging due to incorrect routing.
Innovation Solution
A method involving a dual VLR indication transmitted to the Home Subscriber Server/Home Location Register (HSS/HLR) to trigger the Mobility Management Entity (MME) to initiate a process solving the dual VLR issue, including updating the UE's location information and disconnecting the incorrect VLR connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the dual VLR issue is solved by upgrading the MME or UE to support new information elements (like TMSI based NRI), then the reliability of CS call paging is improved, but the device complexity and upgrade requirements increase
Solution Approach 1:
The patent introduces a new information element called 'VLR registration indication' as an intermediary signal transmitted from the MME to the VLR. This indication acts as a mediator that triggers the VLR to send an Update Location Request to the HSS/HLR, thereby resolving the dual VLR issue without requiring complex upgrades to UE or MME architecture. The intermediary element enables the solving mechanism while keeping the existing system structure intact.
Solution Approach 2:
The patent changes the parameter state by introducing a new flag or indication parameter in the signaling messages between network elements. The 'VLR registration indication' parameter, when set by the MME, changes the behavior of the VLR to initiate location update procedures. This parameter change approach allows the system to detect and resolve dual VLR issues without hardware upgrades or complex software modifications.
2Reliability
If the MME determines whether the serving MSC/VLR is changed, then the dual VLR issue can be solved, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent implements a feedback mechanism where the MME monitors and determines whether the serving MSC/VLR has changed, and based on this determination, sends appropriate signaling (the VLR registration indication) to the VLR. This feedback loop enables automatic detection and resolution of dual VLR issues. The MME uses feedback from location update requests and cancellation messages to detect VLR changes and trigger appropriate corrective actions.
3Reliability
If the VLR sends Update Location Request to HSS/HLR, then the location information is updated correctly, but the loss of time occurs during the correction process
Solution Approach 1:
The patent applies preliminary action by having the MME proactively send the VLR registration indication to the VLR when it detects a dual VLR condition. This preliminary signaling triggers the VLR to immediately send the Update Location Request to the HSS/HLR, preventing further incorrect paging attempts. By acting preliminarily rather than waiting for repeated failures, the system reduces the overall time loss associated with correcting the dual VLR issue.
Data Source
AI summary
The present disclosure provides methods, nodes and computer readable medium for solving a dual VLR issue. The method at a first MSC/VLR includes: determining that a dual VLR issue occurs; and transmitting a dual VLR indication to a HSS/HLR for the HSS/HLR to trigger an MME that is serving a UE to initiate a process of solving the dual VLR issue.