Home Router LMSI Mapping for Mobile Message Routing
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Solution Overview
Problem
The existing Home Router systems in GSM networks face issues with mis-delivery of short messages due to the risk of generating a single MT Correlation ID for two different MSISDNs in a short period, leading to potential mis-delivery of messages to the wrong recipient.
Innovation Solution
The method involves using a Local Mobile Subscriber Identity (LMSI) as a correlation key, which is randomly mapped to multiple MSISDNs, ensuring uniqueness and unpredictability, and incorporating MSISDN prefixes into the LMSI with random padding to prevent fraudulent guessing, thereby decoupling subscriber identity and correlation key for enhanced security and message delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an MT Correlation ID is generated sequentially or at random by the Home Router, then message routing is enabled, but the risk of generating a single MT Correlation ID for two different MSISDNs increases, leading to mis-delivery
Solution Approach 1:
The patent introduces LMSI as a new dimension in the message routing process. Instead of relying solely on MT Correlation ID generated by the Home Router, the system now uses LMSI which is provided by the visited network and embedded in the SRI-SM request. This additional dimension (LMSI) allows the system to cross-reference and verify message routing information, thereby preventing mis-delivery while maintaining efficient routing.
2Object-affected harmful factors
If the Home Router provides a fake IMSI (MT Correlation ID) for security purposes, then subscriber identity protection is improved, but the ability to detect spoofed messages and prevent spam is reduced
Solution Approach 1:
The patent implements a feedback mechanism where the LMSI is used to verify message authenticity. The visited network provides LMSI in the SRI-SM request, which serves as feedback to confirm that the message routing request is legitimate. This feedback loop enables the system to detect spoofed messages and prevent spam while still protecting subscriber identity by using fake IMSI/MT Correlation ID, as the LMSI verification provides the necessary authenticity check.
3Productivity
If the Home Router maintains a cache for MSISDN recall based on IMSI, then service lookup efficiency is improved, but the complexity of managing identity mapping increases
Solution Approach 1:
The patent extracts the identity verification function from the Home Router's cache management. Instead of relying solely on the Home Router's cache of MSISDN-IMSI mappings, the system now extracts and uses LMSI from the visited network's SRI-SM request. This extraction approach simplifies the Home Router's complexity by reducing its cache management burden, while still enabling efficient service lookup through the available LMSI information.
Data Source
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Figure 3
AI summary
A home router network element assigns a correlation key including an LMS1 to an MSISDN in such a way that the risk of short message mis-delivery to a wrong mobile subscriber is very much reduced. This is achieved by projection of MSISDN ranges on correlation key ranges while the correlation key is still unpredictable. The level of correlation key unpredictability is determined by applicable numbering plans and for practical purposes avoids the chance that an MT message originated by a fraudulent party is successfully delivered via the home router.