SOOP-Based PNT Architecture for GPS-Denied Navigation
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Solution Overview
Problem
GPS and GNSS signals are susceptible to external interference, such as jamming, due to their low power, and are unreliable in GPS-denied environments, leading to inaccuracies in navigation systems.
Innovation Solution
A system architecture for providing Position, Navigation, and Timing (PNT) services using Signals of Opportunity (SOOP) in a GPS-denied environment, which includes user equipment, network operations centers, and reference stations equipped with SOOP receivers, utilizing time difference of arrival (TDOA) measurements and clock bias modeling to determine position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS and GNSS signals are used for navigation, then navigation accuracy is improved, but the system becomes susceptible to external interference such as jamming
Solution Approach 1:
The patent changes the fundamental parameter of signal characteristics by transitioning from low-power GPS/GNSS signals to high-power signals of opportunity (cellular, Wi-Fi, broadcast radio/TV signals). This parameter change provides both accurate navigation measurements and inherent resistance to jamming, as the high-power opportunity signals cannot be easily overwhelmed by low-power interference
Solution Approach 2:
The system achieves multi-functionality by utilizing existing infrastructure signals (cellular networks, Wi-Fi access points, broadcast towers) that serve multiple purposes - communication, broadcasting, and navigation. These signals provide both positioning information and inherent anti-jamming capabilities through their high power and widespread infrastructure deployment
2Stability of the object's composition
If GPS is integrated with inertial navigation system (INS), then long-term stability is improved, but INS errors increase over time when GPS becomes unavailable
Solution Approach 1:
The system enables self-service positioning by using widely available infrastructure signals that do not require dedicated navigation satellites. The opportunity signals are already present in the environment for communication and broadcasting purposes, providing continuous positioning capability without relying on GPS satellite availability
Solution Approach 2:
The patent transitions from satellite-based signals to terrestrial infrastructure signals, changing the signal source parameter. This provides continuous positioning coverage in urban canyons and indoor environments where GPS signals are blocked, while maintaining long-term stability through diverse signal sources
3Reliability
If a SOOP-based PNT system uses diverse RF signals, then resistance to interference is improved, but system complexity increases
Solution Approach 1:
The receiver is designed with multi-functionality to process multiple types of RF signals (cellular, Wi-Fi, broadcast) through a unified signal processing architecture. This universal approach provides interference resistance through signal diversity while managing complexity by using common processing blocks for different signal types
Solution Approach 2:
The system segments the signal processing into modular functional blocks - signal acquisition, signal tracking, position calculation - that can handle different signal types independently. This segmentation allows the system to process diverse opportunity signals while maintaining manageable complexity through modular design
4Measurement precision
If reference stations are used for SOOP-based PNT, then positioning accuracy is improved, but dependency on infrastructure increases
Solution Approach 1:
The system achieves self-service positioning by directly measuring time of arrival of opportunity signals and calculating position through trilateration or multilateration algorithms. This eliminates dependency on reference stations by using the inherent timing information in the opportunity signals themselves, reducing infrastructure requirements while maintaining positioning accuracy
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
The SOOP-based PNT system provides reliable and accurate navigation by leveraging diverse and high-power RF signals, reducing dependency on reference stations, and using crowd-sourced data for ephemeris determination, thereby enhancing performance, availability, and integrity in GPS-denied environments.
Implementation Method 1
radio-frequency (RF) signals that are not originally designed for navigation, such as television or radio broadcast signals and cellular network signals
Implementation Method 2
utilizing time difference of arrival (TDOA) measurements to determine position
Data Source
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AI summary
Systems and methods for inertial navigation aided by signals of opportunity (SOOP). One system includes a network operations center (NOC), a reference station, and mobile user equipment. Another system includes a NOC and user equipment without a reference station. In the latter system, the NOC comprises an antenna, a NOC receiver that generates SOOP data derived from SOOP, a computer system that generates SOOP source location/ephemeris data and inter-source clock bias data based on SOOP data generated by the NOC receiver, and a communication device to broadcast the data. The user equipment comprises an antenna, a navigation receiver that generates SOOP data derived from SOOP detected by the antenna of the user equipment, and a navigation computer system that calculates a navigation solution, including a SOOP-derived estimated position of the user equipment, based on SOOP source location/ephemeris data and inter-source clock bias data broadcasted by the NOC and SOOP data generated by the navigation receiver.