Multi-Antenna TOF Estimation for NLOS Wireless Ranging
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Solution Overview
Problem
Existing time-of-flight (TOF) estimation methods in wireless localization are inaccurate in non-line-of-sight (NLOS) conditions due to signal reflections and multipath scenarios, leading to biased measurements that hinder centimeter-accurate distance estimation.
Innovation Solution
A method for TOF estimation with NLOS compensation using multiple antennas on a handheld device, calculating the difference in arrival times of signals at spaced-apart antennas to compensate for NLOS signal paths, allowing for accurate TOF estimation through computationally inexpensive equations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TOF measurement is used in ranging operation, then measurement accuracy is improved, but measurement reliability deteriorates in NLOS conditions
Solution Approach 1:
The patent segments the signal reception process by using multiple antennas (first antenna and second antenna) to independently receive signals from different spatial paths. This segmentation allows the system to distinguish between LOS and NLOS signal components, improving reliability while maintaining accuracy in ranging operations.
Solution Approach 2:
The patent introduces a spatial dimension by deploying multiple antennas at different physical locations and orientations. This dimensional expansion enables the system to capture signal characteristics from multiple angles, allowing differentiation between direct LOS paths and reflected NLOS paths, thereby resolving the reliability-accuracy contradiction in TOF measurements.
2Measurement precision
If multiple antennas are used for NLOS compensation, then TOF estimation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent divides the signal processing task into separate handling for first antenna and second antenna receptions. Each antenna's signal is processed independently to determine arrival times, and the results are combined for NLOS compensation. This segmented approach achieves accurate TOF estimation while keeping the processing logic manageable and device complexity controlled.
Solution Approach 2:
The patent introduces an intermediary computational step that calculates the difference between arrival times at the first and second antennas. This intermediate value serves as a metric for NLOS detection and compensation, enabling accurate TOF estimation without requiring complex hardware modifications or sophisticated signal processing algorithms.
3Reliability
If NLOS compensation calculation is performed, then measurement reliability is improved, but power consumption increases
Solution Approach 1:
The patent applies partial action by performing NLOS compensation calculations only when necessary - specifically when NLOS conditions are detected through the arrival time difference analysis. This selective application of the compensation algorithm reduces unnecessary computational overhead and power consumption while maintaining measurement reliability when needed.
Solution Approach 2:
The system uses the inherent signal arrival time differences captured by the multiple antennas to automatically detect and compensate for NLOS conditions. The antennas themselves provide the data needed for compensation, eliminating the need for external calibration or additional power-intensive processing, thus achieving reliability improvement with minimal power consumption.
Data Source
AI summary
A method is provided for estimating a time-of-flight (TOF) in a wireless communication between first and second devices. The method includes receiving a signal, transmitted from the second device, at first and second antennas of the first device. The second antenna is spaced apart from the first antenna on the first device. A difference in arrival time of the received signal at the first antenna and at the second antenna is computed by the first device. A non-line-of-sight (NLOS) signal path of the received signal in a TOF estimation is compensated for using the difference in arrival time of the received signal between the first antenna and the second antenna. In another embodiment, a communications device having multiple antennas is provided that compensates for the NLOS signal path using the method.