Geographically Aided GPS Positioning Using Selective Cartography
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Solution Overview
Problem
GPS receivers face challenges in accurately determining position in degraded signal environments, such as urban areas with tall buildings, where satellite signals are weak or blocked, leading to inaccurate calculations.
Innovation Solution
A method and apparatus that utilize selective cartography information from a map database to provide geographic aiding, enhancing the positional accuracy of GPS receivers by overlaying initial location data with navigational state information to derive and apply positional corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS receiver operates in degraded signal environments (e.g., urban areas with tall buildings), then satellite signal reception becomes difficult, but positional accuracy deteriorates
Solution Approach 1:
The patent introduces map database information as an intermediary element that mediates between the GPS receiver and the satellite signals. By using cartography data (road networks, geographic features) as a reference framework, the system can correct positional errors without directly improving satellite signal reception. The map matching algorithm acts as a mediator that translates raw GPS coordinates into accurate positions by referencing known geographic structures.
Solution Approach 2:
The patent changes the parameter space by transitioning from relying solely on satellite signal parameters (pseudorange, carrier phase) to incorporating map database parameters (road coordinates, geographic feature locations). This parameter transformation allows the system to compute positional corrections by comparing GPS-derived positions with map-referenced positions, thereby improving accuracy in degraded signal environments.
2Measurement precision
If map database is embedded within GPS receiver to improve positional accuracy, then device size increases, but compactness deteriorates
Solution Approach 1:
The patent extracts only the essential cartography information needed for positional correction from the complete map database, rather than embedding the entire database in the receiver. By extracting and transmitting only relevant map segments (road networks, geographic features in the receiver's current area), the system achieves positional accuracy improvement without requiring large embedded storage capacity in the GPS receiver.
Solution Approach 2:
The patent transitions from a two-dimensional embedded storage solution to a multi-dimensional architecture involving external map servers, wireless communication channels, and selective data transmission. By moving map database storage to an external dimension (remote servers) and using communication channels as a bridge, the system eliminates the need for large embedded storage while maintaining positional accuracy capabilities.
3Measurement precision
If selective cartography information is used to correct initial location, then positional accuracy improves, but computational complexity increases
Solution Approach 1:
The patent segments the computational process into distinct modules: initial position calculation from satellite signals, map matching to identify candidate road segments, positional correction calculation, and final position determination. By segmenting the algorithm into manageable functional blocks, the system reduces overall computational complexity while achieving improved positional accuracy through the integration of cartography information.
Data Source
AI summary
The present invention is related to position calculation and navigation systems, and more particularly, to a method and apparatus for making accuracy improvements to a GPS receiver's navigation solutions. According to a first aspect, selective cartography information from a map database accessed by a GPS receiver from a location-aiding device is integrated into the position calculations performed by the GPS receiver. According to another aspect, selective cartography information includes indices representing associated attributes of geographical objects, such as, a width-indicator index for a road segment.