SIM Network Selection Using Forbidden IMSI Scanning
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Solution Overview
Problem
Existing SIM technologies fail to reliably detect available networks, especially when roaming, as they often attach to non-optimal networks due to limitations in network evaluation and prioritization, particularly within the home country where national roaming is not allowed.
Innovation Solution
The SIM module provides a first subscriber identity that causes updates for a list of forbidden networks, allowing it to detect all available networks by using a forbidden IMSI with an unacceptable MCC and/or MNC, and then selects a network for attachment using the updated list, ensuring all networks are scanned before attaching with a regular IMSI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mobile device uses a regular SIM card with a valid IMSI for network selection, then the device can attach to networks, but it may attach to non-optimal networks because not all available networks are evaluated
Solution Approach 1:
The patent segments the network selection process into two distinct phases: a discovery phase using a test IMSI to identify all available networks, and an attachment phase using the regular IMSI to connect to the optimal network. This segmentation allows comprehensive network evaluation without compromising the reliability of actual network attachment.
Solution Approach 2:
The patent introduces a test IMSI as an intermediary element that enables the device to probe and identify available networks without attempting actual attachment. This intermediary identity allows the device to gather network availability information that would otherwise be inaccessible, improving the accuracy of network evaluation.
2Measurement precision
If the mobile device scans all available networks before attachment, then optimal network selection is achieved, but the process becomes more complex and time-consuming
Solution Approach 1:
The patent leverages the existing network authentication infrastructure to perform network discovery. By using a test IMSI, the device automatically triggers network responses that reveal availability information without requiring complex scanning protocols. The network infrastructure itself provides the discovery service, reducing device complexity.
Solution Approach 2:
The patent performs preliminary network discovery using a test IMSI before the actual network attachment process. This preliminary action identifies all available networks and their characteristics, allowing the device to make an informed selection. The complexity of comprehensive network evaluation is shifted to this preliminary phase rather than being embedded in the attachment process itself.
3Productivity
If the mobile device attaches to the first available network in the priority list, then attachment speed is improved, but the device may miss better networks that were not yet evaluated
Solution Approach 1:
The patent performs preliminary network discovery using a test IMSI to identify and evaluate all available networks before the actual attachment process. This preliminary evaluation ensures that when the device attaches using its regular IMSI, it does so to the optimal network based on comprehensive information, not just the first available option. The speed of attachment is maintained because the evaluation has already been completed in advance.
Solution Approach 2:
The patent segments the network selection process into a discovery phase (using test IMSI to evaluate all networks) and an attachment phase (using regular IMSI to connect quickly to the pre-selected optimal network). This segmentation allows comprehensive network evaluation without sacrificing attachment speed, as the device attaches to a pre-determined optimal network rather than searching during the attachment process.
Data Source
AI summary
A method and an identification module SIM of a device in a mobile communication system wherein the SIM provides a first subscriber identity to the device and receives updates for a list of forbidden networks stored in a memory of the identification module. The SIM uses the received updates as a list of available networks for a second subscriber identity and provides the second subscriber identity to the device.