Motion-Compensated Signal Correlation for Urban GNSS Positioning
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Solution Overview
Problem
Multipath interference and shadow matching inaccuracies in urban canyon environments significantly degrade the accuracy of GNSS positioning systems, particularly for lane-level vehicle positioning and pedestrian street determination, due to undistinguishable reflected signals.
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 compensate for reflected signals by correlating and motion-compensating received signals, using a 3D city map to enhance positioning accuracy.
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 received in directions different from predicted line-of-sight directions
Solution Approach 1:
The system dynamically adjusts the signal processing approach based on receiver motion. Motion compensation is applied adaptively to account for antenna movement during signal integration, allowing the system to handle signals from varying directions including reflected paths while maintaining accuracy
Solution Approach 2:
The system changes the processing parameters by applying motion compensation transformations to the correlation process. This allows the system to identify and utilize signals from non-line-of-sight directions by compensating for the expected phase and frequency shifts caused by receiver motion
2Measurement precision
If motion compensation is applied to enhance signal gain and reception directionality, then signal detection capability is improved, but system complexity increases
Solution Approach 1:
Motion compensation parameters are calculated in advance based on receiver motion data before the correlation process. This preliminary preparation of compensation values simplifies the real-time processing by pre-establishing the transformation parameters needed for motion compensation
Solution Approach 2:
The system introduces motion compensation as an intermediary transformation step between signal reception and correlation. This intermediary process handles the complexity of motion effects separately, allowing the main correlation unit to focus on signal matching while the motion compensation unit manages the directional and phase adjustments
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
Improves positioning accuracy by distinguishing line-of-sight and reflected signals, allowing for enhanced positioning calculations and identification of counterfeit signals, even in challenging environments.
Implementation Method 1
a correlation unit configured to provide a correlation signal by correlating the local signal with the received signal
Implementation Method 2
this technique builds on the principle that motion compensation can provide enhanced signal gain and reception directionality from a moving antenna
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).