Satellite Position Verification for Spoof-Resistant Mobile Terminals
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Solution Overview
Problem
Current satellite-based positioning methods are vulnerable to falsified GNSS positions reported by mobile terminals, particularly in asset tracking applications, where malevolent agents can manipulate data for their benefit, and existing techniques lack inherent security and verification mechanisms.
Innovation Solution
A method involving air-based or space-based positioning using a constellation of satellites that transmits a first radio signal to a mobile terminal, which responds with a second signal, allowing multiple receivers to determine the terminal's position based on transmission and reception times, incorporating identifiers and frequency measurements to verify authenticity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If satellite-based positioning relies on signals broadcast by GNSS, then positioning coverage is achieved, but the position can be falsified by malevolent agents
Solution Approach 1:
Instead of the traditional one-way GNSS signal transmission from satellite to receiver, the patent implements a two-way communication scheme where the satellite transmits a first signal to the mobile terminal, which then responds with a second signal back to the satellite. This inverted communication flow enables the satellite to verify the terminal's position independently of the terminal's self-reported GNSS data, thereby resolving the vulnerability to falsification while maintaining system reliability.
Solution Approach 2:
The patent introduces a feedback mechanism where the mobile terminal receives a first signal from the satellite, processes it, and sends a second signal back containing position information and authentication data. The satellite then uses this feedback to verify the terminal's position through cost function evaluation. This closed-loop feedback system ensures position verification reliability without significantly increasing overall system complexity.
2Reliability
If two-way position validation is implemented, then spoofing resistance is improved, but system complexity increases
Solution Approach 1:
The patent implements partial two-way validation by having the satellite transmit a first signal and receive a second signal from the terminal, but not requiring full bidirectional verification for all scenarios. The system evaluates a cost function based on the exchanged signals to determine position validity, applying verification only when necessary. This partial action approach provides spoofing resistance while avoiding the complexity of complete two-way validation in all cases.
Solution Approach 2:
The patent changes the parameters of signal exchange by using specific message formats containing authentication data, position coordinates, and timing information. The first signal from the satellite contains verification challenges, while the second signal from the terminal contains responses and position data. These parameter changes enable efficient spoofing detection without requiring complex additional hardware payloads.
3Measurement precision
If multiple airborne or spaceborne receivers are used to determine position, then position accuracy is improved, but the number of required receivers increases
Solution Approach 1:
The patent segments the positioning function by having different satellites perform different roles: one satellite transmits the first signal to the terminal, while one or more satellites (including the same one) receive the second signal. This segmentation allows the system to use multiple receivers for position determination without requiring a fully redundant constellation, as each satellite can contribute to both transmission and reception functions.
Solution Approach 2:
The patent implements multi-functionality where satellites in the constellation serve multiple purposes: they can act as transmitters of the first signal, receivers of the second signal, and processing nodes for position determination. This universal approach allows the same satellite infrastructure to perform multiple functions, reducing the total number of receivers needed while maintaining position determination accuracy through cooperative multi-satellite operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures reliable positioning of mobile terminals by reducing spoofing and manipulation, with minimal increase in complexity, and enables secure verification of reported positions using a cost function and least-squares techniques.
Implementation Method 1
determining or verifying the position of the mobile terminal based on a time of transmission of the first radio signal at the airborne or spaceborne transmitter and times of reception of the second radio signal at respective ones of the plurality of airborne or spaceborne receivers
Implementation Method 2
transmitting a first radio signal to the mobile terminal for prompting the mobile terminal to transmit a second radio signal
Data Source
AI summary
A method of air-based and/or space-based positioning of a mobile terminal for determining or verifying a position of the mobile terminal includes: at an airborne or spaceborne transmitter, transmitting a first radio signal to the mobile terminal prompting the mobile terminal to transmit a second radio signal, wherein the first radio signal corresponds to a first message; at the mobile terminal, in response to receiving the first radio signal, transmitting the second radio signal, wherein the second radio signal corresponds to a second message; receiving the second radio signal at a plurality of airborne or spaceborne receivers; and determining or verifying the position of the mobile terminal based on a time of transmission of the first radio signal at the transmitter and times of reception of the second radio signal at respective ones of the receivers. Further disclosed is a constellation of satellites for space-based positioning of a mobile terminal.