GNSS Receiver Parallel Search for Faster First Positioning Fix
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Solution Overview
Problem
Existing GNSS receivers face challenges in obtaining a reliable and time-efficient first positioning fix, particularly when powered on, due to unknown time and range errors, atmospheric delays, and receiver hardware delays, which complicate code phase synchronization more than frequency synchronization.
Innovation Solution
A parallel search method is employed using controlled satellite-specific offsets to distribute search starting points, minimizing common mode errors, and iteratively refining prepositioning information as satellites are detected, allowing simultaneous search of multiple satellites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a serial search scheme is used to obtain a first positioning fix, then the search process is simple to implement, but the detection time is prolonged and robustness is reduced
Solution Approach 1:
The search process is segmented into parallel independent search channels, one for each satellite. Each channel performs code phase and frequency search simultaneously, transforming the sequential search into parallel searches that can proceed independently without blocking each other.
Solution Approach 2:
The search approach transitions from a single-dimensional sequential search to a multi-dimensional parallel search space. By introducing parallel search channels as an additional dimension, the system can explore multiple satellites simultaneously rather than sequentially.
2Loss of time
If a parallel search scheme is used to reduce detection time, then the detection time is reduced, but the complexity of code phase synchronization increases
Solution Approach 1:
The system performs preliminary actions by determining prepositioning information, code phase search ranges, and frequency search ranges before initiating the parallel search. This pre-processing step establishes the search parameters in advance, reducing the complexity during the actual search execution.
Solution Approach 2:
The system changes search parameters dynamically by determining code phase search ranges and frequency search ranges based on prepositioning information. This allows the parallel search to operate with optimized parameters for each satellite, managing complexity through parameter adaptation rather than fixed rigid parameters.
3Reliability
If prepositioning information is used to determine search ranges and starting points, then the robustness in obstructed scenarios is improved, but the computational requirements increase
Solution Approach 1:
The system applies local quality by determining satellite-specific code phase search ranges and frequency search ranges based on individual satellite prepositioning information. Each satellite gets customized search parameters tailored to its specific characteristics and obstruction conditions, rather than using uniform parameters for all satellites.
Data Source
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AI summary
The present disclosure relates to a method (100) for performing a parallel search for a first positioning fix in a Global Navigation Satellite System, GNSS, receiver. The method (100) comprises determining (102) prepositioning information, wherein the prepositioning information comprises a receiver information and a satellite information for each satellite in a plurality of satellites. The method (100) further comprises determining (103) 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 (100) further comprises determining (104) 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 (100) further comprises performing (105) 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.