ePDG Selection Signaling for Lawful Roaming Access
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Solution Overview
Problem
Current cellular network selection methods for 3GPP devices do not adequately address the need for lawful intercept obligations when roaming, particularly in selecting an Evolved Packet Data Gateway (ePDG) in a Visited Public Land Mobile Network (VPLMN), and lack means for verifying if a Home PLMN ePDG can be used, leading to potential abuse and revenue loss.
Innovation Solution
Implementing methods for a 3GPP device to receive ePDG selection indicators via Location Area Update, Routing Area Update, Tracking Area Update, or Attach Accept messages, and using Protocol Configuration Options, to ensure compliance with lawful intercept obligations and proper ePDG selection in VPLMN or Home PLMN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE selects an ePDG in the VPLMN to meet lawful intercept obligations, then compliance with local laws is improved, but roaming revenue may be lost due to forced use of VPLMN infrastructure
Solution Approach 1:
The patent implements dynamic ePDG selection where the UE can switch between VPLMN ePDG (for LI compliance) and HPLMN ePDG (for revenue optimization) based on received indicators. The network can dynamically control UE behavior through selection indicators transmitted in attach accept messages or protocol configuration options, allowing flexible adjustment between compliance and revenue goals.
Solution Approach 2:
The patent changes the selection parameter from static (always VPLMN or always HPLMN) to dynamic by introducing selection indicators that modify the ePDG selection behavior. The UE receives indicators containing PLMN identities or FQDNs that change the selection criteria, enabling the system to adapt between compliance mode and revenue optimization mode based on network policies.
2Reliability
If the UE is instructed to select a VPLMN ePDG without verification means, then LI obligations are enforced, but the mechanism can be abused to capture roaming revenue
Solution Approach 1:
The patent implements feedback mechanisms where the UE verifies VPLMN identity through received indicators and can report back to the network. The selection indicator contains verifiable information (PLMN ID, FQDN) that allows the UE to confirm it is connecting to the intended VPLMN ePDG, preventing unauthorized revenue capture while maintaining LI compliance.
Solution Approach 2:
The patent performs preliminary verification before ePDG selection by transmitting selection indicators in advance (in attach accept messages or protocol configuration options). The UE receives and processes this verification information before establishing the connection, ensuring that only authorized VPLMN ePDGs are selected while preventing abuse of the mechanism.
3Loss of energy
If the UE uses HPLMN ePDG while roaming in VPLMN, then roaming revenue is optimized, but lawful intercept obligations may not be met
Solution Approach 1:
The patent enables dynamic switching between HPLMN ePDG selection (for revenue optimization) and VPLMN ePDG selection (for LI compliance) based on received indicators. The network can dynamically control this behavior by transmitting appropriate selection indicators, allowing the system to optimize revenue in non-LI jurisdictions while ensuring compliance where required.
4Adaptability or versatility
If PLMN is identified by FQDN instead of PLMN ID, then service provider flexibility is improved, but existing LI enforcement mechanisms cannot configure the PLMN
Solution Approach 1:
The patent makes the ePDG selection mechanism universal by supporting both PLMN ID-based identification (for traditional LI enforcement) and FQDN-based identification (for service provider flexibility). The selection indicator can contain either type of identifier, allowing the same mechanism to serve both regulatory compliance needs and commercial flexibility needs.
Solution Approach 2:
The patent introduces FQDN as an intermediary between the UE and the ePDG when PLMN ID is not available or not desired. The FQDN acts as a flexible identifier that can resolve to the appropriate ePDG, enabling service providers to use non-traditional PLMN identifiers while still maintaining functional equivalence with existing LI enforcement mechanisms.
Data Source
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AI summary
A method, computer program product and a user equipment (UE) are provided for selecting a second network node for connection. A first message is sent to a first network node. The first message includes UE request capabilities. A second message is received from the first network node. The second message includes an indication. A second network node is selected for connecting to the network based on the received indication. The second network node may be an Evolved Packet Data Gateway (ePDG). The UE request capabilities may indicate ePDG selection and/or allow discovery of details of one or more ePDGs for connection, the indication contains at least one of a Fully Qualified Domain Name (FQDN) or an indication that the UE must attempt to connect using only an ePDG belonging to a Registered Public Land Mobile Network (RPLMN).