GNSS Receiver Positioning Using 3D Shading Maps
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Solution Overview
Problem
Global navigation satellite systems (GNSS) face significant challenges in urban areas due to blocked lines of sight and signal reflections from tall buildings and obstacles, leading to inaccurate position calculations, with errors ranging from tens of meters to hundreds of meters, and sometimes resulting in an inability to calculate a position at all.
Innovation Solution
The method involves classifying satellites as line-of-sight (LOS) or non-line-of-sight (NLOS) using signal strength and creating a three-dimensional shading map to determine the position of a GNSS receiver by eliminating subregions based on the shading surface defined by these classifications, allowing for improved position calculation by accounting for the presence or absence of line of sight to satellites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional GNSS position calculation methods are used in urban areas, then the calculation can be performed using available satellite signals, but the position accuracy deteriorates significantly due to blocked lines of sight and signal reflections
Solution Approach 1:
The method segments the three-dimensional space into multiple subregions based on satellite visibility. Each subregion is characterized by specific line-of-sight conditions to satellites, allowing the system to identify and eliminate subregions where the receiver cannot be located based on observed satellite signals. This segmentation transforms the continuous space into discrete zones with different visibility properties.
Solution Approach 2:
The invention extends the traditional two-dimensional GNSS positioning problem into three dimensions by creating a three-dimensional shading map that accounts for building structures and their impact on satellite visibility. The method uses elevation angles and azimuth angles to define three-dimensional subregions, adding vertical dimension analysis to improve position accuracy in urban canyons.
2Productivity
If four pseudoranges are used to determine receiver position, then the calculation can be completed with minimal satellite signals, but the position error increases in urban environments with limited sky visibility
Solution Approach 1:
The invention introduces a three-dimensional shading map as an intermediary between the satellite signals and the position calculation. This shading map, derived from urban environment data, acts as a mediator that provides additional constraints on possible receiver locations. By combining signal-based pseudorange measurements with environment-based visibility constraints, the system achieves more accurate positioning than pseudoranges alone.
Solution Approach 2:
The method replaces part of the traditional signal-based positioning mechanism with an environment-based constraint system. Instead of relying solely on mathematical intersection of pseudoranges, the system substitutes in the three-dimensional visibility analysis that eliminates impossible locations, thereby improving accuracy without requiring additional satellite signals.
3Reliability
If signal strength-based satellite classification is implemented, then line-of-sight and non-line-of-sight satellites can be distinguished, but the device complexity increases
Solution Approach 1:
The system performs preliminary classification of satellites into line-of-sight and non-line-of-sight categories before the main position calculation process. By using signal strength thresholds and elevation angle criteria to pre-sort satellites, the method prepares the data in advance, making the subsequent three-dimensional shading map generation and subregion elimination more efficient and manageable.
Data Source
AI summary
The invention, in some embodiments, relates to the field of global navigation satellite systems, and more particularly to the field of methods and devices for improving accuracy of position determination by receivers of global navigation satellite systems. Some embodiments of the invention relate to methods for generating a three-dimensional (3-D) representation of an urban area by a receiver of a global navigation satellite system using blocked lines of sight to satellites of the system. Additional embodiments of the invention relate to methods for transmitting a three-dimensional (3-D) representation of an urban area by a receiver of a global navigation satellite system for improving calculation of location by the global navigation satellite system receiver.