Bounded Time Delay Estimation for Wireless Positioning
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Solution Overview
Problem
Existing self-localization methods for wireless devices in multi-path environments, such as densely built-up areas, face inaccuracies due to multi-path errors in time delay estimation, which conventional processing techniques fail to adequately address.
Innovation Solution
The method involves linking motion/position tracking feedback to the time delay estimation process to limit non-direct path signal estimates, using bounded time delay estimation to filter out multi-path errors by setting range values based on known characteristics, mobility, and relative displacements between devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional processing techniques (thresholds, filtering, averaging) are applied to time delay estimation, then motion smoothing is achieved, but multi-path errors remain significant and position accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by using feedback from the tracker to establish expected time delay ranges before performing time delay estimation. This pre-establishment of bounds based on known mobility characteristics prevents multi-path errors from corrupting the estimation, thereby maintaining both motion smoothing and position accuracy
Solution Approach 2:
The patent implements feedback by using the tracker's position estimates to constrain the time delay estimation process. The expected range of time delays is determined based on feedback about the device's known mobility and previous position estimates, creating a closed-loop system that maintains accuracy while smoothing motion
2Device complexity
If earliest arrival signal selection is used to determine direct path, then processing complexity is reduced, but multi-path errors cause erroneous range calculations in dense environments
Solution Approach 1:
The patent uses feedback from the tracker about expected position changes to validate whether the earliest arrival signal is indeed the direct path signal. By comparing the time delay of the earliest signal against the expected range based on mobility feedback, the system can confirm or reject the earliest signal as valid, maintaining low complexity while improving accuracy
Solution Approach 2:
The patent performs preliminary action by calculating expected time delay ranges based on known mobility characteristics before selecting the direct path signal. This pre-computation of valid ranges allows the system to quickly validate candidate signals without complex processing, reducing errors while maintaining simplicity
Data Source
AI summary
A method and apparatus for estimating the position of a mobile device in a multi-path environment. In one example, the method includes receiving a plurality of reference signals from a corresponding plurality of reference devices, for each reference signal, calculating expected time delay boundaries, for each reference signal, estimating a range between the device and the corresponding reference device based on a measured time delay of the reference signal falling within calculated time delay boundaries to produce a plurality of range estimates, and filtering the plurality of range estimates to generate a composite estimate of the position of the device.