Geolocation via Scatterer Virtualization in NLoS
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Solution Overview
Problem
Conventional geolocation techniques fail in true non-line-of-sight (NLoS) environments with severe multipath conditions, where the signal from the transmission source reaches the observer through unknown scatterers, leading to degraded accuracy and potential geolocation errors, especially in environments with no detectable direct line-of-sight (LoS) signal.
Innovation Solution
The described techniques employ a linearized algorithm for geolocation that uses physical layer detection of signals, identifying and estimating the location of LoS scatterers, and their emission times, allowing the reconstruction of the source location even in NLoS conditions by treating scatterers as virtual receiver antenna elements, without requiring sophisticated infrastructure or special receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional geolocation techniques are used in NLoS environments, then the system can operate without specialized infrastructure, but the geolocation accuracy degrades significantly due to severe multipath conditions
Solution Approach 1:
The patent converts the harmful multipath reflections into beneficial information by treating scatterers as virtual antenna elements. Instead of discarding reflected signals as noise, the system identifies and utilizes them to create additional virtual receiving points, transforming the NLoS condition into a usable geolocation resource that improves positioning capability in environments where direct line-of-sight is blocked
Solution Approach 2:
The patent introduces scatterers as intermediary elements between the transmission source and the receiver. By identifying scatterers that reflect signals and treating them as virtual antenna elements, the system creates an intermediary geolocation path that bridges the NLoS gap, allowing position estimation to proceed through reflected signal paths rather than requiring direct line-of-sight
2Measurement precision
If sophisticated infrastructure or special receivers are deployed to improve geolocation in NLoS conditions, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent enables the existing receiver to serve itself by processing multipath signals through physical layer detection and scatterer identification algorithms. The system uses its own received signals, including reflections, to create virtual antenna elements and perform geolocation without requiring external specialized infrastructure, allowing the receiver to improve its own NLoS performance through software-based signal processing
Solution Approach 2:
The patent changes the parameter interpretation by treating time-delayed multipath signals not as degraded versions of the original signal but as distinct signals from virtual antenna elements. By changing how the system parameters (signal arrivals) are interpreted and modeled, the existing hardware can achieve improved NLoS geolocation performance through algorithmic processing rather than hardware modification
3Measurement precision
If conventional techniques are used with detectable LoS signals, then geolocation accuracy is maintained, but the system fails when no direct line-of-sight signal is present
Solution Approach 1:
The patent creates a universal geolocation methodology that functions in both LoS and NLoS conditions. The physical layer detection approach and scatterer identification algorithm provide a unified framework that automatically adapts to the environmental conditions, eliminating the need for separate processing paths for different signal conditions and enabling consistent operation across diverse propagation environments
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate geolocation in severe multipath environments, improving positioning system performance even in cases with impaired or no direct line-of-sight between the receiver and satellites, and does not necessitate a change in methodologies when faced with NLoS conditions, providing a paradigm shift over previous techniques.
Implementation Method 1
The antenna array receives a plurality of RF signals from the transmission source... physical layer detection of signals
Implementation Method 2
signal from the transmission source reaches the observer through unknown scatterers... severe multipath conditions
Data Source
AI summary
In selected embodiments, a process of geolocation of a transmitter uses a receiver with an antenna array that is non-line-of-sight (NLoS) to the transmitter. A first plurality of scatterers within line-of-sight (LoS) of the array is located using multilateration based on time difference of arrival (TDoA) from the first scatterers, and applying a spatial consistency requirement. Time of emission/reflection from the first scatterers is also determined. The coordinates and timing of the first scatterers are used to locate either the transmitter or another set of scatterers, by applying multilateration to the TDoA at the first scatterers, and applying the spatial consistency requirement. The process is iteratively repeated until the transmitter is identified. The multilateration may be linearized without sacrificing precision. In each iteration, a non-singularity requirement is applied to ensure that the selected scatterers produce unambiguous results.