PDN Connection Optimization in Visited PLMN via TAU
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Solution Overview
Problem
Current 3GPP recommendations do not provide a clear method for establishing PDN connectivity in a Visited PLMN while maintaining a connection to a Home PLMN during UE roaming, requiring an explicit standalone procedure for UE to set up PDN connectivity.
Innovation Solution
A method that automatically allocates a default bearer to UE in the Visited PLMN during the Tracking Area Update procedure, allowing for local breakout of user plane or control plane traffic, with control either by the Home PLMN or initiated by the UE, using a new flag 'extra-default-bearer-request' in the Tracking Area Update message.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE uses the standalone procedure for UE requested PDN connectivity as per current 3GPP recommendations, then the UE can establish connectivity to a new PDN in VPLMN, but the procedure becomes complex and requires explicit standalone steps beyond Tracking Area Update
Solution Approach 1:
The patent merges the PDN connectivity establishment procedure with the existing Tracking Area Update (TAU) procedure. By integrating the default bearer allocation into the TAU process, the system eliminates the need for separate standalone procedures, thereby reducing complexity while maintaining adaptability for PDN connectivity in VPLMN
Solution Approach 2:
The patent performs preliminary action by pre-configuring the UE with a flag indicating whether it is allowed to establish a default bearer in VPLMN. This pre-configuration enables automatic bearer allocation during TAU without requiring complex runtime decision-making procedures
2Ease of operation
If the UE automatically establishes a default bearer in VPLMN upon entry, then seamless connectivity is achieved, but control over bearer allocation becomes more complex requiring new flags and parameters
Solution Approach 1:
The patent implements self-service by enabling the UE to automatically establish default bearers in VPLMN based on pre-configured permissions. The UE autonomously manages bearer allocation during TAU procedures without requiring complex manual control mechanisms, achieving seamless connectivity through self-configuring behavior
Solution Approach 2:
The patent introduces parameter changes by adding a new flag to the TAU request message that indicates whether the UE is allowed to establish a default bearer in VPLMN. This parameter-based control mechanism simplifies the control architecture while enabling flexible bearer management
3Reliability
If the current 3GPP procedure is used for PDN connectivity, then explicit control is maintained, but the procedure requires multiple standalone steps including PDN connectivity request, Create Default Bearer Request, and Bearer Setup Request
Solution Approach 1:
The patent merges multiple standalone procedures (TAU, PDN connectivity request, Create Default Bearer, Bearer Setup) into a single integrated TAU procedure. This consolidation maintains reliable connection control through existing signaling frameworks while significantly reducing the time required by eliminating redundant sequential steps
Data Source
AI summary
The invention concerns a method for optimizing a UE PDN (Packet Data Network) connection when said UE enters a VPLMN (Visited PLMN) characterized by automatically allocating a default bearer to said UE in said VPLMN during Tracking Area Update procedure. The method according to the invention is preferably but not exclusively used for allowing a local breakout of user plane or control plane traffic when the UE is roaming between several PLMNs.