Wireless Positioning Time Correction via Channel Impulse Response
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Solution Overview
Problem
Current wireless positioning systems face challenges in achieving accurate location tracking of transmitters due to low accuracy in time of arrival measurements, especially in multipath propagation environments, which affects localization and time synchronization among locator nodes.
Innovation Solution
A method that determines an improved time of arrival value by calculating a time correction from the channel impulse response, using a ratio of values associated with a first peak and a leading edge, and applying this correction to obtain a more accurate time of arrival, while also considering multipath propagation, and further enhances accuracy through frequency offset correction and time synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If simple time of arrival measurement methods are used, then device complexity is reduced, but measurement precision deteriorates due to low accuracy in locating the direct signal in multipath environments
Solution Approach 1:
The patent applies preliminary action by using frequency offset correction before time of arrival measurement. The method first corrects frequency offsets in the received signal, then performs correlation to obtain the channel impulse response, and finally measures the time of arrival. This preliminary frequency correction prepares the signal for more accurate subsequent processing, resolving the contradiction by improving measurement precision through preparatory signal conditioning without requiring complex real-time processing during the actual measurement.
2Reliability
If traditional time of arrival measurement methods are used, then device complexity is minimized, but reliability deteriorates due to inaccurate localization affecting safety and security applications
Solution Approach 1:
The patent implements feedback by using the channel impulse response obtained from correlation as input for determining the time of arrival. The method measures the time of arrival based on the correlation output, which contains information about the propagation channel characteristics. This feedback loop where the channel response informs the time measurement improves reliability by accounting for multipath effects, while the systematic approach keeps the added complexity manageable through algorithmic processing.
3Measurement precision
If signal strength-based positioning is used, then device complexity is reduced, but measurement precision deteriorates in areas with insufficient access point density
Solution Approach 1:
The patent replaces signal strength-based positioning with a time of arrival measurement system that uses correlation-based channel impulse response analysis. Instead of relying on signal strength thresholds and database lookups (mechanical/system-based approach), the invention uses signal processing techniques (correlation, frequency correction) to precisely measure the time of arrival. This substitution enables accurate positioning in areas with lower access point density, improving both precision and adaptability coverage.
Data Source
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AI summary
This disclosure concerns estimating the location of a transmitter using multiple pairs of locator nodes with known locations and measuring time of arrival of a signal received from a transmitter. A processor of a location estimation node first determines time difference of arrival values from time of arrival values measured by each pair of locator nodes. The processor then determines likelihood information for multiple candidate locations of the transmitter and estimates the location of the transmitter from the likelihood information. A processor further determines an initial time of arrival value for the received signal and channel impulse response for a radio channel between the transmitter and receiver. The processor then determines a time correction from the channel impulse response based on a first peak of the channel impulse response and a leading edge of the first value. The processor finally determines an improved time of arrival value of the received signal.