Reference Time Scale Validation for Spoof-Resistant GNSS Timing
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Solution Overview
Problem
Current GNSS receivers lack a security check to determine signal corruption or spoofing, leading to unreliable and untrustworthy Position, Velocity, and Time (PVT) computations, as they directly compute integrity information based on received signals without ensuring the accuracy of the computed PVT.
Innovation Solution
A Reference Time Scale Dissemination System that provides User Terminals with dissemination data indicating the difference between their computed GNSS Time Scale and a Reference Time Scale, allowing for correction and validation to ensure reliable replication of the Reference Time Scale, comprising a Dissemination Data Provider, a Validation Service Provider, and User Terminals equipped with GNSS receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS receivers compute integrity information directly based on received signals, then the computation process is simple and fast, but the reliability and trustworthiness of PVT computations cannot be ensured due to lack of security checks against signal corruption or spoofing
Solution Approach 1:
The patent introduces a Reference Time Scale Dissemination System as an intermediary between the GNSS satellites and user receivers. This system provides a trusted reference time scale that mediates the verification process, allowing receivers to authenticate signals without directly implementing complex security checks. The intermediary validates the integrity of time signals, resolving the contradiction by externalizing the security verification function.
Solution Approach 2:
The system performs preliminary validation of time signals by establishing a trusted reference time scale before the actual PVT computations are performed. By pre-validating the integrity of time signals through the dissemination system, the patent ensures reliability upfront, allowing subsequent computations to proceed with confidence without requiring complex real-time security checks.
2Measurement precision
If GNSS receivers use redundancy of received signals to estimate accuracy of computed PVT, then the estimation process is straightforward, but no security check is available to determine signal corruption or spoofing
Solution Approach 1:
The patent implements a feedback mechanism where the Reference Time Scale Dissemination System provides continuous validation information back to user receivers. This feedback loop allows receivers to compare their computed time scales against the trusted reference, enabling them to detect signal corruption or spoofing attempts. The feedback ensures both precision and trustworthiness by providing ongoing verification of measurement accuracy.
Solution Approach 2:
The Reference Time Scale Dissemination System acts as an intermediary that bridges the gap between signal reception and trust verification. It provides an independent validation layer that confirms the integrity of time signals, allowing receivers to achieve both precise measurements and reliable verification without directly implementing complex security protocols.
3Stability of the object's composition
If User Terminals replicate the Reference Time Scale locally, then the time scale alignment is achieved, but validation of Time Offsets and Scatters is required to ensure integrity
Solution Approach 1:
The Reference Time Scale Dissemination System serves as an intermediary that handles the complex validation of Time Offsets and Scatters. By externalizing this validation function, the patent allows User Terminals to focus on stable time scale replication while the intermediary ensures integrity through automated validation processes, reducing the complexity burden on individual receivers.
Solution Approach 2:
The system enables self-service validation where the dissemination system automatically validates Time Offsets and Scatters against the reference time scale. This self-validating mechanism ensures stability of time scale replication without requiring complex manual validation processes at each User Terminal, as the system performs integrity checks autonomously.
Data Source
AI summary
A Reference Time Scale Dissemination System (RTS-DS) is provided that includes a RTS Dissemination Data Provider (RTS-DDP) and a User Terminal. The RTS Dissemination Data Provider is equipped with a radio receiver designed to receive radio signals and to compute a RTS-DDP Computed Time Scale based on received radio signals. The User Terminal (UT) is equipped with a Radio Receiver designed to receive radio signals and to compute a UT Computed Time Scale based on received radio signals, and with a Clock Device designed to be locked to the UT Computed Time Scale and to provide a UT Local Time Scale resultingly locked to the UT Computed Time Scale. The RTS-DPP is designed to receive a Reference Time Scale, and compute, at a RTS-DDP Computed Time, Time Quantities indicative of a difference between the RTS-DDP Computed Time Scale and the received Reference Time Scale, including a Time Scatter indicative of a difference between the RTS-DDP Computed Time and a corresponding Reference Time, and a Time Offset indicative of a mean value, computed over a timespan, of a number of differences between RTS-DDP Computed Times and corresponding Reference Times.