Multipath Signal Positioning in Cluttered Environments

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Solution Overview

Problem

Existing navigation systems in cluttered environments, such as urban canyons or enclosed structures, face challenges due to multipath signals that lead to inaccurate position measurements, requiring costly infrastructure and prior knowledge of the environment.

Innovation Solution

The system utilizes multipath signals by constructing a model using recursive estimation techniques, allowing for real-time tracking of differential delays and estimating multipath parameters, which can be used for three-dimensional localization even when direct paths are blocked, eliminating the need for prior knowledge of the local infrastructure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional navigation systems use direct-path RF signals for positioning, then positioning can be achieved in line-of-sight conditions, but positioning accuracy deteriorates when multipath signals are present in cluttered environments

Engineering Contradiction:

Improvepositioning reliabilityVSAvoidpositioning accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent converts multipath signals from harmful interference into useful positioning information by constructing a signal model that includes both direct and multipath components. The system estimates parameters such as angle of arrival (AOA) and time of arrival (TOA) for multipath signals and uses these estimates to determine position, thereby transforming the previously detrimental multipath effects into beneficial positioning data that improves reliability in non-line-of-sight conditions.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Device complexity

If prior art systems treat multipath signals as errors to be eliminated, then positioning can be simplified, but positioning accuracy deteriorates in cluttered environments where direct paths are unreliable

Engineering Contradiction:

Improvesystem complexityVSAvoidpositioning accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the fundamental parameters used for positioning by estimating AOA and TOA from multipath signal characteristics rather than relying solely on direct-path signals. The system constructs a signal model with parameters including multipath component indices, angles of arrival, and times of arrival, and uses these transformed parameters to achieve accurate positioning in cluttered environments where traditional direct-path methods fail.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If autonomous navigation approaches use inertial systems with special algorithms, then positioning can be achieved without infrastructure, but system cost increases and prior knowledge of building dimensions is required

Engineering Contradiction:

ImproveautonomyVSAvoidsystem cost

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent introduces RF signal characteristics (multipath components) as an intermediary between the positioning system and the environment. Instead of relying on expensive inertial measurement units or prior knowledge of building dimensions, the system uses readily available RF signal information including multipath arrival times and angles to determine position, thereby reducing system cost and complexity while maintaining autonomy.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Measurement precision

If cooperative infrastructure systems use specialized transmitters and receivers, then positioning accuracy can be improved, but infrastructure cost increases and multipath sensitivity remains

Engineering Contradiction:

Improvepositioning accuracyVSAvoidinfrastructure cost

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the positioning system universal by enabling standard RF receivers to perform accurate positioning in cluttered environments through multipath signal utilization. Instead of requiring specialized transmitters and receivers with complex infrastructure, the system uses conventional RF technology combined with advanced signal processing to achieve both accuracy and cost-effectiveness, thereby eliminating the need for expensive specialized infrastructure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 maintains tracking accuracy in scenarios where direct-path techniques fail, reducing costs and utilizing all available information, including multipath signals, to provide reliable positioning without the need for expensive infrastructure or prior knowledge of the environment.

Implementation Method 1

the multipath signals resulting when transmitted signals are reflected by various objects within the local environment

Methodology Applied

Scientific EffectMultipath signal propagation: Reflection

Data Source

PatentUS7679561B2Systems and methods for positioning using multipath signals

Publication Date: 2010.03.16 THE CHARLES STARK DRAPER LABORATORY INC

AI summary

A signal processing technique for RF active, passive, or aided localization approaches that utilizes multipath signals as additional measurements with a filter or estimator, e.g., a nonlinear filter. The filter uses indirect and direct path measurements or any other available signals to build parametric models of observable indirect paths. If one or more direct path measurements are subsequently lost (e.g., due to obstruction), the filter maintains an estimate of the position of the person or object of interest using indirect path measurements.