AMF GPSI Association for 5G Lawful Interception
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The Access and Mobility Management Function (AMF) in 5G core networks only knows a list of General Public Subscription Identifiers (GPSIs) for a User Equipment (UE) based on a given Subscription Permanent Identifier (SUPI), which is insufficient for supporting Lawful Interception (LI), as it cannot accurately associate a GPSI with a PDU session, leading to incomplete interception of signaling and user plane traffic.
Innovation Solution
The solution enables the AMF to identify the exact GPSI among a list of GPSIs associated with a PDU session for a UE, allowing for precise interception of relevant traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the AMF stores only a list of GPSIs for a UE, then the storage complexity is reduced, but the ability to support Lawful Interception is insufficient
Solution Approach 1:
The solution segments the GPSI list into individual GPSI entries, each with a unique identifier. This allows the AMF to store multiple GPSIs in a structured manner while maintaining the ability to individually identify and associate each GPSI with specific PDU sessions, thereby supporting Lawful Interception without excessive complexity
Solution Approach 2:
The patent introduces an intermediary mechanism (GPSI association information) that links GPSIs to PDU sessions. This intermediary structure enables the AMF to maintain both the simplified GPSI list storage and the detailed association needed for Lawful Interception, resolving the contradiction between storage simplicity and interception capability
2Ease of operation
If the AMF associates each PDU session with only one GPSI, then the association process is simplified, but the interception coverage is incomplete
Solution Approach 1:
The solution segments the association relationship into multiple independent GPSI-PDU session linkages. Each GPSI can be individually associated with relevant PDU sessions, allowing the system to maintain simplified one-to-one associations while achieving comprehensive multi-GPSI coverage through multiple such associations
Solution Approach 2:
The patent implements a universal association mechanism where each GPSI in the list can serve multiple functions - being associated with different PDU sessions as needed. This multi-functional approach allows complete interception coverage while maintaining the simplicity of individual GPSI-PDU session associations
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
Disclosed herein is a method by an AMF node 120-4 operative in a 5GS that comprises a UE 112 associated with a Subscriber Permanent Identifier (SUPI) that is associated with subscription data of the UE. The method comprises: sending towards a SMF node, a request relating to a PDU Session of the UE and comprising a Request Type that is set to Existing PDU Session; and receiving from the SMF node, a response comprising a Generic Public Subscription Identifier (GPSI) of the PDU session, which GPSI is associated with the SUPI and which GPSI is to be used in networks outside the 5GS for addressing the subscription data of the UE.