Directional Pruning of Transmitters for Positioning
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Solution Overview
Problem
In urban terrestrial positioning systems, the presence of multipath signals due to obstructions like buildings leads to inaccurate position estimates, as existing techniques struggle to effectively account for errors caused by both multipath and poor geometric distribution of transmitters, resulting in a tradeoff between these errors.
Innovation Solution
The method involves grouping ranging signals based on their quality and geographic characteristics, selecting range measurements from higher-quality signals, and using these measurements to estimate the receiver's position while minimizing geometric position error by forming groups that optimize transmitter distribution around the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multipath signals are excluded from position estimation, then measurement precision improves, but geometric distribution of transmitters deteriorates
Solution Approach 1:
The patent segments the set of all detectable transmitters into multiple groups based on signal quality metrics. By dividing transmitters into quality-based segments, the system can selectively use high-quality transmitters for position estimation while ensuring adequate geometric coverage through the grouping structure, thus resolving the contradiction between precision and distribution.
Solution Approach 2:
The patent applies local quality assessment by evaluating signal quality metrics (such as signal-to-noise ratio, received signal strength) for each individual transmitter and assigning quality values. This allows the system to identify and preferentially use transmitters with better local signal quality while maintaining overall geometric distribution, thereby improving position estimation accuracy without sacrificing coverage.
2Adaptability or versatility
If all detectable ranging signals are used for position determination, then geometric distribution improves, but measurement precision deteriorates due to multipath errors
Solution Approach 1:
The patent implements partial action by using only a subset of detectable transmitters for position estimation. Instead of using all available transmitters, the system selects a quality-based subset that provides sufficient geometric distribution while excluding transmitters that would introduce significant multipath errors, thus achieving both adequate coverage and improved precision.
Solution Approach 2:
The patent changes the selection parameter from purely geometric criteria to quality-based criteria. By introducing signal quality metrics as the primary selection parameter, the system transforms the transmitter selection process to prioritize measurement precision while the grouping mechanism ensures geometric distribution requirements are still met.
3Measurement precision
If a quality criterion is applied to filter ranging signals, then measurement precision improves, but the number of available signals decreases
Solution Approach 1:
The patent segments transmitters into quality-based groups and uses multiple groups for position estimation. This segmentation approach ensures that while individual groups may have fewer transmitters, the combined use of multiple groups provides a sufficient total number of signals, thus maintaining both quality and quantity requirements.
Solution Approach 2:
The patent merges results from multiple quality-based transmitter groups to produce the final position estimate. By combining information from several groups rather than relying on a single filtered set, the system maintains an adequate number of available signals while ensuring each contributing signal meets quality criteria, thus resolving the quantity-precision tradeoff.
Data Source
AI summary
Described are systems and methods for estimating a position of receiver using ranging signals from different regions in a network of transmitters. In some embodiments, each ranging signal that exceeds a quality criterion is assigned to one of several defined regions based on a characteristic of that ranging signal. A maximum number of ranging signals per region may be selected and used during trilateration.