Motion-Compensated Positioning for Urban Multipath Signals
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Solution Overview
Problem
Multipath interference and shadow matching errors significantly degrade positioning accuracy in urban environments, particularly in GNSS systems, leading to ranging errors that hinder lane-level positioning and street determination.
Innovation Solution
A system that includes a local signal generator, receiver, motion module, correlation unit, motion compensation unit, signal analysis unit, and metric determination unit to identify and account for signal reflections, and motion analysis unit to determine the physical metric using motion compensated correlation techniques to determine the physical metric, which includes a correlation and uses motion analysis techniques to enhance positioning accuracy by distinguishing between line-of-sight and reflected signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shadow matching technique is used to improve positioning in urban canyons, then positioning accuracy is enhanced where 3D city model is available, but positioning errors worsen when signals are successfully received after reflection at positions where the 3D city model predicts no reception
Solution Approach 1:
The system dynamically adapts the signal processing approach based on receiver motion. Motion compensation is applied to exploit Doppler frequency shifts that differ between line-of-sight and reflected signals, allowing the system to dynamically identify and preferentially process line-of-sight signals while suppressing reflected signals, thereby resolving the contradiction between enhancing positioning accuracy and avoiding reliability degradation from multipath errors
Solution Approach 2:
The system changes the frequency domain parameters of signals through motion compensation. By applying motion compensation based on receiver velocity and signal direction, the system induces different Doppler shifts for line-of-sight and reflected signals, enabling parameter-based differentiation and selection of reliable line-of-sight signals for positioning calculations
2Measurement precision
If motion compensation is applied to enhance signal gain, then line-of-sight signal reception is improved, but reflected signals may also be enhanced causing positioning errors
Solution Approach 1:
The system applies motion compensation with different characteristics for different signal directions. By determining the direction of line-of-sight signals and applying motion compensation specifically tailored to those directions, the system enhances signal gain locally for line-of-sight paths while avoiding enhancement of reflected signals from other directions, thus resolving the contradiction between improving signal gain and reducing multipath interference
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
Enhances positioning accuracy by identifying and compensating for reflected signals, allowing for improved lane-level positioning and street determination by using motion-compensated correlation to preferentially enhance line-of-sight signal gain and reduce the impact of multipath interference.
Implementation Method 1
this technique builds on the principle that motion compensation can provide enhanced signal gain and reception directionality from a moving antenna
Implementation Method 2
a correlation unit configured to provide a correlation signal by correlating the local signal with the received signal
Implementation Method 3
Multipath interference is a notorious problem for positioning using Global Navigation Satellite System (GNSS) signals. In an urban canyon environment GNSS signals can be reflected one or more times before being received at a receiver
Data Source
AI summary
A system is disclosed for determining a physical metric such as position. The system comprises a local signal generator (8) configured to provide a local signal and a receiver (4) configured to receive a signal having properties corresponding to those in a signal transmitted by a trusted remote source. An inertial measurement unit (12) is configured to provide a measured or assumed movement of the receiver. A correlator (6) is configured to provide a correlation signal by correlating the local signal with the received signal. A motion compensation unit (14) is configured to provide motion compensation of at least one of the local signal, the received signal, and the correlation signal based on the measured or assumed movement. A signal analysis unit (16) is configured to determine whether the received signal includes a component received in a direction that is different to a line-of-sight direction between the receiver and the trusted remote source, wherein the determination is based on the correlation signal. Finally, a metric determination unit or positioning unit (20) is configured to determine a physical metric associated with the receiver, such as its position, based on the determination made by the signal analysis unit (16).