Roaming Network Selection via Encrypted Priority Lists
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Solution Overview
Problem
Mobile operators face challenges in ensuring that a subscriber's terminal connects to the preferred network while roaming, as existing methods rely on SMS updates that can be blocked by visited operators, leading to unintended network selection based on signal strength rather than pre-defined preferences.
Innovation Solution
A method that sends a request for connection with an identifier of the visited area, receiving a response message containing a list of preferred networks, and prioritizing connections to these networks by disconnecting and reconnecting to them, using existing request-response exchanges like attachment or tracking area updates, and encrypting the list with a shared key to prevent tampering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SMS messages are used to push configuration files with preferred network lists to the SIM card, then the terminal can be updated with operator preferences, but the visited operator can detect and block these SMS messages, preventing the terminal from receiving the preferred network list
Solution Approach 1:
The patent introduces an intermediary mechanism where the preferred network list is embedded within standard roaming procedure messages (such as ULR/ULA or attachment requests/responses) rather than being sent via SMS. These intermediary messages are part of the established roaming protocol exchange between the terminal, visited network, and home network, making them difficult to block without disrupting normal roaming operations. The mobility management entity or gateway acts as an intermediary that injects the preferred network list into these standard message flows.
2Reliability
If the SMS message includes a security key specific to the SIM card, then the update can be authenticated as coming from the home operator, but the visited operator can still detect and block the SMS before it reaches the terminal
Solution Approach 1:
The patent combines the preferred network list transmission with existing authenticated roaming procedure messages. The preferred network list is merged into messages that already carry authentication mechanisms (such as signed attachment responses or authenticated location update acknowledgments). This combination ensures that the preferred network list is delivered through an already-authenticated channel, eliminating the need for separate SMS authentication while maintaining security.
3Ease of operation
If the terminal selects the attachment network based on signal strength criteria, then the terminal can connect to available networks, but the selection may unduly favor networks not forming part of the preferred list
Solution Approach 1:
The patent implements a feedback mechanism where the terminal receives the preferred network list and uses it to guide its network selection process. The terminal's network selection logic is updated to prioritize networks from the preferred list while still considering signal strength criteria. This feedback loop ensures that the terminal's automatic selection aligns with operator preferences by continuously referencing the received preferred network list during roaming operations.
Data Source
AI summary
A method for connecting a terminal outside the range of its home network, to a network of a visited area covered by a plurality of networks. The method includes sending a request relating to the connection, including an identifier relating to the visited area, receiving a response message to the request, including a list of at least one network of the plurality of networks, to which the terminal should connect in priority, disconnecting the terminal and connecting the terminal to the priority network of the list. A processing method includes receiving the request including an identifier relating to the visited area, obtaining, on the basis of the identifier, the list of at least one network from the plurality of networks, to which the terminal should connect in priority, and sending a response message to the request, including the list.