Network Node SMS Restoration via Triggered TAU
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Solution Overview
Problem
In wireless communication networks, particularly for NB-IoT devices, the inability to support IMSI detach during EPS attach with SMS only leads to challenges in restoring Short Message Service (SMS) service after a VLR failure, resulting in delayed service restoration and potential disruption of ongoing PS services.
Innovation Solution
A method is introduced where a network node sends a message to a radio network node to trigger a UE to send a Tracking Area Update (TAU) request with SMS only, using a new cause code, thereby enabling the network node to restore the SMS service without waiting for a UE-initiated TAU procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network node waits for a UE-initiated TAU procedure to restore SMS service after VLR failure, then the UE can initiate the procedure, but the service restoration is delayed and PS services may be disrupted
Solution Approach 1:
The network node performs preliminary action by proactively triggering the TAU procedure before the UE initiates it. The network node sends a trigger message to the radio network node, which then initiates the TAU procedure on behalf of the UE, thereby reducing the restoration delay and preventing PS service disruption.
2Productivity
If the network node triggers UE to send TAU request with SMS only, then SMS service can be restored faster, but the network node must implement new cause codes and messaging mechanisms
Solution Approach 1:
The network node utilizes existing TAU request messaging mechanisms and cause codes, extending their functionality to include SMS-only restoration scenarios. By making the existing messaging system multi-functional, the patent avoids introducing entirely new communication protocols while still achieving faster service restoration.
3Adaptability or versatility
If NB-IoT devices use EPS attach with SMS only, then the devices can access SMS service, but they cannot support IMSI detach during the attach procedure
Solution Approach 1:
The patent extracts the SMS restoration functionality from the standard IMSI detach procedure and implements it as a separate, network-initiated TAU trigger mechanism. This allows NB-IoT devices to maintain their simplified EPS attach with SMS only capability while still achieving reliable SMS service restoration after VLR failure, without requiring full IMSI detach support.
Data Source
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AI summary
A method performed by a network node for restoring a Short Message Service (SMS) service in a connection between a User Equipment (UE) and a communications network is provided. The UE is attached to the communications network with Evolved Packet System (EPS) attach and SMS only, via a radio network node, a Visitor Location Register (VLR) Mobile Switching Centre (MSC), and the network node. When receiving information that indicates a restart of the VLR MSC in the connection, network node sends (202) to the radio network node, an indication to trigger the UE to send a Tracking Area Update (TAU) request with SMS only. The network node receives (203) the TAU request with SMS only, triggered by the UE according to the indication sent to the radio network node. The network node then restores (204) the SMS service based on information in the TAU request with SMS only, received from the UE.