Lawful Intercept Mediation Session Correlation
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Solution Overview
Problem
Existing Lawful Interception systems using NAS-dependent target identities struggle to distinguish between different user sessions, leading to interference with non-LI NAS activities and inability to provide real-time session isolation due to the intrinsic non-session-based nature of these identities, which affects the delivery of Intercept Related Information and Content Communications to Law Enforcement Agencies.
Innovation Solution
A method and device that utilize a session-specific Correlation Identification Number (CIN) to correlate Intercept Related Information and Communications Content data packets, generated using target identification data and Framed-IP-addresses from accounting server messages, allowing for real-time identification and differentiation of user sessions even in NAS-dependent scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If NAS-dependent target identities are used for lawful interception, then many user sessions can be intercepted at once with just one warrant, but different user sessions cannot be distinguished among each other
Solution Approach 1:
The patent segments the target identity into two distinct parts: the NAS-dependent target identity (for efficient bulk interception) and a session-specific identifier (for distinguishing individual sessions). This segmentation allows the system to maintain both high interception efficiency and precise session identification by treating these as separate correlatable elements.
Solution Approach 2:
The patent introduces an intermediary correlation mechanism that links the NAS-dependent target identity with session-specific identifiers. This intermediary layer enables the system to bridge between the coarse-grained NAS-level interception and fine-grained session-level identification, allowing Law Enforcement Agencies to reconstruct individual user sessions from aggregated interception data.
2Ease of operation
If warrant activation command is sent only once to the NAS, then NAS equipment performance is maintained, but real-time session isolation cannot be provided
Solution Approach 1:
The patent applies preliminary action by pre-configuring the NAS with the target identity and interception parameters before actual user sessions are established. This allows the NAS to be prepared for interception without being flooded with activation commands, while session-specific identifiers are generated and correlated as sessions are created, maintaining both NAS performance and session isolation.
Solution Approach 2:
The patent adds another dimension to the interception system by introducing session-specific identifiers that operate at a different level than the NAS-dependent target identity. This dimensional addition enables session isolation without requiring changes to the NAS configuration or performance, as the session-level correlation happens at the mediation function level.
3Quantity of substance
If traffic mirroring is performed at the NAS, then intercepted data can be captured, but NAS performance is heavily influenced
Solution Approach 1:
The patent extracts the heavy traffic mirroring operation from the NAS and relocates it to the Mediation Function. The NAS only performs lightweight identification and forwarding of traffic based on pre-configured target identities, while the Mediation Function handles the resource-intensive tasks of session correlation, data aggregation, and session reconstruction, thus reducing NAS power consumption while maintaining interception capability.
Data Source
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AI summary
This disclosure relates to a method S100 and a device for correlating in a Lawful Intercept Mediation system, LIMS, received Intercept Related Information, IRI, and, Communications Content, CC, data packets of a 5 target's lawfully intercepted session for deliverance over HI2 and HI3 interfaces, respectively, by means of a session-specific Correlation Identification Number, CIN.