PLMN Reselection via PSAP Termination Failure Metrics
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Solution Overview
Problem
Existing public land mobile networks (PLMNs) face challenges in identifying and mitigating fraudulent cell sites that cause E911 public safety answer point (PSAP) termination failures.
Innovation Solution
The system and method involve user equipment (UE) attempting connections to PSAP, communicating metrics upon failure, and peer-to-peer communication with other UEs to identify fraudulent cell sites. The PLMN determines a probability score based on these metrics and updates a forbidden public land mobile network (FPLMN) list to prevent connections to fraudulent sites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the PLMN network allows UEs to connect to any cell site, then network coverage and accessibility are improved, but fraudulent cell sites can exploit this to cause PSAP termination failures and compromise emergency service reliability
Solution Approach 1:
The system implements feedback by having UEs report PSAP termination failure metrics back to the PLMN. When a UE experiences a PSAP termination failure, it communicates metrics corresponding to the failure to the PLMN, which then uses this feedback to identify fraudulent cell sites and update the FPLMN list, preventing future connections to these sites.
Solution Approach 2:
The PLMN acts as an intermediary between UEs and cell sites. It receives metrics from UEs about PSAP termination failures, processes this information to determine probability scores for fraudulent activity, and then communicates updated FPLMN lists to UEs. This intermediary role allows the system to maintain open network accessibility while filtering out fraudulent sites through the FPLMN mechanism.
2Reliability
If the PLMN implements strict verification of all cell sites, then network security is improved, but the complexity of network operations and the time required for verification increase
Solution Approach 1:
The system implements self-service by enabling UEs to autonomously detect PSAP termination failures and report metrics to the PLMN. Individual UEs perform verification functions by attempting PSAP connections and communicating failure metrics, distributing the verification burden across the network rather than requiring centralized verification of all cell sites, thus reducing operational complexity while maintaining security.
Solution Approach 2:
The PLMN uses parameter changes by analyzing metrics from multiple UEs and determining probability scores based on aggregated data. Instead of verifying each cell site individually through complex procedures, the system changes the verification approach to statistical analysis of termination failure metrics, updating the FPLMN list based on probability thresholds, which simplifies the verification process while maintaining security.
3Measurement precision
If the PLMN collects and analyzes metrics from multiple UEs to identify fraudulent cell sites, then detection accuracy is improved, but the amount of data communication and processing increases
Solution Approach 1:
The system applies partial action by having UEs report only when PSAP termination failures occur, rather than continuously reporting all connection metrics. This event-driven approach collects sufficient data for fraud detection without requiring constant data communication, balancing detection accuracy with reduced data traffic. The PLMN processes metrics from multiple UEs to determine probability scores, using just enough data to achieve reliable fraudulent site identification.
Data Source
AI summary
Systems and methods are provided for automatic PLMN serving system reselection based on E911 PSAP termination failures. For example, a UE may initiate a call for emergency services on a network provided by a cell site simulator. When the connection fails, metrics corresponding to the termination failure are communicated to the PLMN the next time the UE connects to a legitimate network. The fraudulent cell sites may be communicated by the UE to other UEs via peer-to-peer communication and/or added to an FPLMN list to prevent other UEs from connecting to networks provided by the fraudulent cell sites.