UAV Positioning Using Carrier Frequency Offset Without Range Signals
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Solution Overview
Problem
Existing methods for determining the position of unmanned aerial vehicles (UAVs) require range-related measurements, such as time of arrival, which necessitate high accuracy time synchronization and additional signaling, and are often tailored to specific base stations, making them inefficient and inflexible.
Innovation Solution
The method utilizes carrier frequency offset (CFO) measurements from multiple base stations to determine the position of a moving UAV without requiring range measurements, using a model that incorporates CFO measurements to estimate the UAV's position and velocity, employing an interacting-multiple-model filter process to account for different movement modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If range measurements (time of arrival, radar) are used to determine UAV position, then position accuracy is improved, but device complexity and signaling overhead increase
Solution Approach 1:
The patent extracts and utilizes carrier frequency offset (CFO) measurements from existing uplink signals already present in the wireless communication system. Instead of adding new range measurement signals, the invention extracts positioning information from routine communication signals, thereby avoiding additional signaling overhead while maintaining position determination capability
Solution Approach 2:
The patent replaces traditional mechanical/range-based positioning methods (time of arrival, radar) with a signal processing approach based on carrier frequency offset measurements. This substitution transforms the positioning problem from a geometric range measurement task into a frequency domain analysis task, eliminating the need for complex time synchronization and additional signaling infrastructure
2Measurement precision
If high accuracy time synchronization is implemented for range measurements, then position determination accuracy is improved, but device complexity and implementation difficulty increase
Solution Approach 1:
The patent substitutes time-domain range measurement methods with frequency-domain CFO measurement methods. By measuring carrier frequency offsets in uplink signals from multiple base stations, the system determines UAV position without requiring precise time synchronization between base stations or complex time of arrival calculations, thereby eliminating the time synchronization complexity bottleneck
Solution Approach 2:
The patent introduces carrier frequency offset measurements as an intermediary parameter that bridges communication signals and position information. Instead of directly measuring range or time of arrival, the system uses CFO - a byproduct of signal reception - as an intermediate measurement that indirectly reveals position information, simplifying the overall measurement process
3Reliability
If additional signaling is added for range measurements, then position tracking capability is improved, but loss of time and signaling overhead increase
Solution Approach 1:
The patent enables the existing uplink communication signals to serve dual purposes: both data transmission and position reporting. The UAV's regular uplink signals automatically provide CFO measurements that can be used for positioning, eliminating the need for separate positioning signals or additional signaling protocols, thereby achieving position tracking without additional signaling overhead
Solution Approach 2:
The patent makes the uplink communication signals universal by enabling them to simultaneously perform communication and positioning functions. The same signals used for data transmission also carry position information through their carrier frequency offsets, eliminating the need for dedicated positioning signals and reducing overall signaling requirements
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
Enables accurate tracking of UAVs without additional signaling, allowing for efficient position and velocity determination, even in the absence of range measurements, and reduces computational complexity by using CFO measurements.
Implementation Method 1
obtaining, for each of three or more base stations, one or more measurements of a carrier frequency offset for one or more signals sent between the moving UAV and the respective base station
Data Source
AI summary
A method of determining the position of a moving unmanned aerial vehicle (UAV) is provided. The method comprises obtaining, for each of three or more base stations, one or more measurements of a carrier frequency offset (CFO) for one or more signals sent between a moving UAV and the respective base station. The method further comprises inputting the CFO measurements into a model to determine a position of the UAV, in which inputs to the model do not include range measurements of the UAV with respect to the three or more base stations.