LTE Carrier-Phase UAV Navigation With Cycle Slip Detection
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Solution Overview
Problem
Global navigation satellite systems (GNSS) are unreliable and inaccurate in deep urban areas due to signal attenuation and susceptibility to jamming or spoofing, making them unsuitable for unmanned aerial vehicle (UAV) navigation in environments like urban canyons, where accurate and reliable navigation is crucial.
Innovation Solution
A navigation framework using Long-Term Evolution (LTE) carrier phase measurements and an extended Kalman filter (EKF) for UAV navigation, which includes cycle slip detection and compensation to achieve sub-meter-level accuracy, leveraging the stability and geometric diversity of LTE signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS signals are used for UAV navigation, then navigation coverage is provided, but navigation accuracy and reliability deteriorate in deep urban canyons due to signal attenuation and susceptibility to jamming or spoofing
Solution Approach 1:
The patent applies multi-functionality by using LTE signals for both communication and navigation purposes. The system processes LTE signals to extract carrier phase measurements for navigation, enabling the same signal infrastructure to serve dual functions. This resolves the contradiction by providing reliable navigation in urban environments where GNSS fails, while maintaining measurement precision through specialized signal processing of LTE carrier phases.
Solution Approach 2:
The patent changes the fundamental parameter of signal type from GNSS to LTE carrier phase measurements. By detecting and processing LTE carrier phase information, the system achieves sub-meter navigation accuracy in urban canyons where GNSS signals are attenuated or jammed. This parameter change enables reliable operation in environments previously unsuitable for precision navigation.
2Measurement precision
If LTE carrier phase measurements are used for navigation, then navigation accuracy improves to sub-meter level, but measurement errors due to cycle slips must be detected and compensated
Solution Approach 1:
The patent implements feedback through cycle slip detection and compensation mechanisms. The system continuously monitors LTE carrier phase measurements, detects cycle slips when they occur, and compensates for the resulting errors. This feedback loop maintains measurement reliability while preserving the high accuracy benefits of carrier phase measurements, resolving the contradiction between precision and reliability.
Solution Approach 2:
The patent applies beforehand cushioning by preparing compensation strategies in advance for potential cycle slips. The system establishes detection thresholds and compensation algorithms before navigation operations begin, enabling rapid response when cycle slips occur. This pre-prepared approach maintains measurement reliability without sacrificing the high accuracy of carrier phase measurements.
Data Source
AI summary
This disclosure is directed to sub-meter level navigation accuracy for Unmanned Aerial Vehicles (UAVs) using broadband communication signals, such as cellular long-term evolution (LTE) signals. A framework and methods are provided using a receiver and controller to produce at least one of carrier phase, code phase, and Doppler frequency measurements from received LTE signals. Single difference measurements may be used to remove clock bias. LTE ENodeB clock biases are initialized using the known initial position of the UAV. The measurements are fused via an extended Kalman filter (EKF) to estimate the UAV position and integer ambiguities of the carrier phase single difference measurements. LTE signals can have different carrier frequencies and conventional algorithms do not estimate the integer ambiguities. Processes are described to detect cycle slip, where the carrier phase measurements from the LTE eNodeB multiple antenna ports are used to detect cycle slip.