Satellite Positioning Assistance Data Ordering for Obstruction Handling
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Solution Overview
Problem
Existing satellite-based positioning systems, such as GPS, face challenges in improving the probability of successful positioning and reducing the time required for mobile stations, particularly due to variations in signal strength affected by terrain and environment.
Innovation Solution
The method involves generating assistance data sequences for mobile stations that account for local obstructions by selecting and ordering satellites based on their likelihood of successful detection, using control data that reflects terrain-specific conditions, such as Azimuth/Elevation distributions and elevation masks, to optimize signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If satellites are selected using a fixed cell-independent scheme based on elevation and azimuth spread, then the measurement geometry is improved, but the probability of successful positioning decreases and time to first fix increases in environments with local obstructions
Solution Approach 1:
The system performs preliminary actions by pre-determining Azimuth/Elevation distributions and control data for each cell based on local obstruction characteristics. This allows the mobile station to receive pre-calculated assistance data ordered according to the specific geographic environment, rather than using a generic fixed selection scheme. The preliminary characterization of each cell's obstruction pattern enables optimized satellite selection tailored to local conditions.
Solution Approach 2:
The invention applies local quality by creating cell-specific Azimuth/Elevation distributions that reflect the unique obstruction characteristics of each geographic location. Instead of using a uniform satellite selection criterion across all cells, the system tailors the assistance data ordering to match local environmental features such as urban canyons, mountains, or indoor structures. This localized approach optimizes the probability of successful positioning for each specific area.
2Device complexity
If satellites are selected using a fixed cell-independent scheme, then the system complexity is reduced, but the average time required for positioning increases
Solution Approach 1:
The system performs preliminary actions by pre-calculating and storing Azimuth/Elevation distributions and control data for each cell during network setup or maintenance periods. This preliminary work eliminates the need for complex real-time calculations when a mobile station needs positioning. The assistance data is pre-ordered based on local obstruction patterns, so the mobile station can immediately use the optimized sequence without performing complex selection algorithms, thus reducing positioning time while maintaining manageable system complexity.
3Ease of operation
If assistance data is transmitted without considering local obstructions, then the transmission process is simplified, but the detection probability of satellites decreases
Solution Approach 1:
The invention applies local quality by ordering assistance data according to cell-specific Azimuth/Elevation distributions that reflect local obstruction characteristics. For each cell, the system determines which satellite elevation and azimuth ranges are most likely to be blocked by local structures, and accordingly prioritizes assistance data for satellites in less obstructed directions. This localized tailoring of data transmission ordering improves detection probability without significantly complicating the transmission process, as the ordering information is pre-calculated and stored in the network.
Data Source
AI summary
A method, an apparatus and a computer program for providing assistance data for satellite based positioning of mobile stations operating in a first cell of a cellular radio communication system utilizing ranging signals transmitted by satellites. A sequence of assistance data for positioning of a mobile station operating in the first cell is generated (306) by including in said sequence assistance data associated with individual satellites in a set of at least four satellites. At least one of said set of satellites and the order in which assistance data associated with individual satellites occurs in said sequence of assistance data is selected (305) utilizing control data associated with the first cell and reflecting local obstructions in the first cell or its immediate surroundings affecting reception of said ranging signals in the first cell. The invention also includes a method, an apparatus and a computer program for updating (311) said control data utilizing information derived from positionings of mobile stations in the first cell.