HPLMN ePDG Selection in Roaming via ANQP and ANDSF

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Solution Overview

Problem

In cellular networks, particularly in 3GPP LTE and 5G networks, users face challenges when roaming due to constraints in using home network resources and policies, especially when connected to untrusted wireless local area networks, leading to undesirable connectivity scenarios.

Innovation Solution

The implementation of a mechanism that allows users to selectively connect to Home Public Land Mobile Network (HPLMN) Enhanced Packet Data Gateways (ePDGs) based on pre-configured or dynamic preferences, using Access Network Query Protocol (ANQP) and Access Network Discovery and Selection Function (ANDSF) rules, to prioritize HPLMN resources over Visited Public Land Mobile Network (VPLMN) resources during roaming.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE uses VPLMN resources and policies during roaming, then connectivity is maintained in visited networks, but the UE cannot access HPLMN resources and policies which may provide better service quality

Engineering Contradiction:

Improveservice qualityVSAvoidnetwork resource selection flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system dynamically allows the UE to switch between using VPLMN and HPLMN resources based on roaming status and user preferences. When roaming is detected and HPLMN resources are available, the UE can be configured to use HPLMN ePDG for data bearer establishment, providing adaptability while maintaining service quality.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the network selection parameter by introducing a mechanism to prefer HPLMN ePDG over VPLMN ePDG during roaming. This is achieved through configuration parameters that indicate whether to use HPLMN or VPLMN resources, allowing the system to optimize service quality by selecting the appropriate network resources based on the roaming scenario.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the UE connects to untrusted WLAN for network access, then connectivity is established, but security and trustworthiness of the connection is compromised

Engineering Contradiction:

Improveconnectivity establishmentVSAvoidconnection trustworthiness

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention introduces an intermediary mechanism (HPLMN ePDG) that mediates between the UE and the untrusted WLAN network. By establishing data bearers through the trusted HPLMN ePDG even when accessing via untrusted WLAN, the system maintains connection ease while ensuring trustworthiness through the intermediary gateway that enforces security policies.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the UE always uses HPLMN resources during roaming, then service quality is improved, but complexity of network selection and configuration increases

Engineering Contradiction:

Improveservice qualityVSAvoidnetwork selection mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary detection of roaming status and checks for available HPLMN ePDG before establishing data bearers. This preliminary action simplifies the network selection process by automatically determining whether to use HPLMN or VPLMN resources based on pre-defined conditions, reducing the complexity of manual configuration while maintaining service quality.

Inventive Principle:

Principle #10Preliminary action

4Adaptability or versatility

If the UE retrieves ePDG selection information via WLAN ANQP during roaming, then network discovery is enabled, but wrong ePDG selection may occur leading to connectivity issues

Engineering Contradiction:

Improvenetwork discovery capabilityVSAvoidePDG selection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The invention implements feedback mechanisms where the UE receives indication information from the network about whether HPLMN ePDG should be used during roaming. This feedback refines the ePDG selection process by providing accurate guidance based on network conditions and roaming agreements, improving selection accuracy while maintaining the adaptability of network discovery through ANQP.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3298829B1Device, system and method of hplmn preferred epdg selection in roaming scenarios

Publication Date: 2020.09.16 INTEL CORP

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AI summary

User equipment (UE), and access point (AP) of an unsecured network and method of providing a quasi-orthogonal multiple access (QOMA) resources are generally described. The UE may determine whether it is roaming and if not connect to a home public land mobile network (HPLMN) Enhanced Packet Data Gateway (ePDG). The UE, when roaming, may retrieve ePDG selection information indicating to which of the HePDG and a visited public land mobile network (VPLMN) ePDG (VePDG) to attempt to connect, and connect to whichever of the HePDG and the VePDG is indicated by the ePDG selection information. The UE, when roaming and cannot connect to any PLMN, may extract from the ePDG selection information a default fully qualified domain name (FQDN) corresponding to a particular PLMN and connect to the ePDG corresponding to the particular PLMN through the AP based on the default FQDN.