Roaming UE ePDG Selection for Lawful Interception
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Solution Overview
Problem
Current mobile communication systems face challenges in monitoring communications of roaming users, especially when they use wireless local area networks (Wi-Fi), making it difficult to legally intercept communications for security purposes such as counter-terrorism efforts.
Innovation Solution
A method and user equipment (UE) that select an enhanced packet data gateway (ePDG) in a visited public land mobile network (V-PLMN) instead of relying solely on the home network's ePDG, by determining the availability of an ePDG indication and list within the V-PLMN, and using system information blocks, attach accept messages, or access network discovery and selection functions to prioritize local ePDG selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If roaming users connect to Wi-Fi networks in visited networks, then communication convenience is improved, but lawful interception capability deteriorates
Solution Approach 1:
The patent introduces an ePDG as an intermediary component in the visited network that acts as a mediator between the UE and the home network. When a roaming UE connects to Wi-Fi, the ePDG intercepts the connection request and establishes a controlled data bearer through which all traffic must pass. This intermediary structure enables lawful interception while maintaining Wi-Fi connectivity, as the ePDG can monitor and forward traffic to the appropriate interception points without disrupting the user's communication experience.
2Reliability
If roaming users connect to home network ePDG, then lawful interception capability is maintained, but network overload increases
Solution Approach 1:
The patent implements local quality by deploying ePDG functionality within the visited network rather than requiring all roaming traffic to route back to the home network. The visited network's ePDG handles local interception and traffic management, meaning that only local traffic needs to be monitored locally, while maintaining the ability to intercept communications. This distributes the network load to where the traffic actually originates, preventing home network overload while preserving interception capability.
3Device complexity
If ePDG selection is centralized in home network, then network control is simplified, but interception effectiveness for roaming users deteriorates
Solution Approach 1:
The patent segments the ePDG functionality into two parts: home network ePDG for initial authentication and policy management, and visited network ePDG for actual traffic interception and forwarding. The UE is instructed to select the visited network's ePDG when roaming, which then establishes the data bearer. This segmentation allows the home network to maintain simplified control logic while the visited network's ePDG handles the complex task of local traffic interception, thereby improving interception effectiveness without significantly increasing overall network control complexity.
Data Source
AI summary
One disclosure of the present invention provides a method for selecting an enhanced packet data gateway (ePDG). The method may be performed by a user equipment (UE) and comprise: determining, by the UE which has roamed from a home public land mobile network (H-PLMN) to a visited public land mobile network (V-PLMN), whether there exists an indication for selecting ePDG in the V-PLMN; determining, by the UE, whether the UE has attached to any PLMN in the V-PLMN, when it is determined that there exists the indication; determining, by the UE, whether there exists an ePDG PLMN list for the any PLMN in the V-PLMN, when it is determined that the UE has attached to the any PLMN; and selecting, by the UE, at least one ePDG in the ePDG PLMN list.