GNSS Receiver Parallel Search for Faster First Positioning Fix
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Solution Overview
Problem
Existing GNSS receivers face challenges in achieving a reliable and time-efficient first positioning fix, particularly when powered on or in scenarios with obstructed or weak satellite signals, leading to variable detection times and reduced robustness in conventional search methods.
Innovation Solution
A parallel search method is employed, utilizing prepositioning information, code phase and frequency search ranges, and satellite-specific offsets to synchronize with multiple satellites simultaneously, reducing the time required for the first positioning fix and enhancing robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a conventional serial search scheme is used to obtain a first positioning fix, then the search process is simple to implement, but the time required for positioning is excessive and detection reliability is reduced
Solution Approach 1:
The search space is segmented into multiple parallel search channels, each dedicated to a specific satellite. This allows simultaneous searching of multiple satellites rather than sequentially, dramatically reducing the time to obtain a first positioning fix while maintaining manageable complexity through structured division of the search task.
Solution Approach 2:
Prepositioning information is determined before the parallel search begins, including initial estimates of receiver position, time, and satellite ephemeris data. This preliminary preparation enables the parallel search to start from informed starting points rather than blind searches, reducing the search time required while maintaining accuracy.
2Loss of time
If prepositioning information is used to accelerate the search process, then the time to first positioning fix is reduced, but the robustness in challenging conditions (obstructed or weak signals) deteriorates
Solution Approach 1:
The search process dynamically adapts to challenging conditions by monitoring signal quality and adjusting the search strategy. When obstructed or weak signals are detected, the system can switch between satellites or adjust search parameters, maintaining robustness while still benefiting from the time-saving parallel search approach.
Solution Approach 2:
Multiple satellites are pre-processed and prepared for parallel searching, with their search parameters and starting points pre-determined based on prepositioning information. This ensures that when a satellite becomes available (even in challenging conditions), the receiver can immediately begin searching with optimized parameters, reducing acquisition time while maintaining reliability through pre-prepared search configurations.
3Speed
If a parallel search scheme is implemented to reduce positioning time, then the speed of obtaining first positioning fix is improved, but the complexity of the search process increases
Solution Approach 1:
The parallel search process is segmented into independent channels, each handling a specific satellite. This segmentation enables simultaneous processing of multiple satellites, achieving high speed in obtaining the first positioning fix. The segmented structure also makes the complex parallel process more manageable through modular design, where each channel operates independently with standardized procedures.
Data Source
AI summary
The present disclosure relates to a method for performing a parallel search for a first positioning fix in a Global Navigation Satellite System (GNSS) receiver. The method includes, in some instances, determining prepositioning information, wherein the prepositioning information includes a receiver information and a satellite information for each satellite in a plurality of satellites. The method further includes determining a code phase search range and a frequency search range, based on the prepositioning information, for each satellite in the plurality of satellites. The method further includes determining a starting point information for each satellite in the plurality of satellites, wherein each respective starting point information is representative of an offset from a center of a search range of the respective satellite. The method further includes performing the parallel search for all satellites in the plurality of satellites based on the respective code phase search range, the respective frequency search range and the respective starting point information.