Radio Target Distance Estimation Using Multipath Correlation

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Solution Overview

Problem

Radio wave detection devices lack the ability to accurately estimate distance to a target due to errors caused by multipath waves, which complicate the estimation based on reception power fluctuations.

Innovation Solution

A target distance estimation device that processes reception signals from both direct and multipath waves using a multipath composite wave signal simulation to improve estimation accuracy by correlating these signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If target distance is estimated using propagation loss based on reception power, then distance estimation can be performed without transmission function, but estimation accuracy deteriorates due to multipath wave interference

Engineering Contradiction:

Improvedistance estimation capabilityVSAvoidtarget distance estimation accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The reception signal is segmented into direct wave components and multipath wave components through correlation processing. By generating a multipath composite wave signal that simulates the composite of direct and multipath waves, the system separates the useful direct wave information from the interfering multipath components, enabling accurate distance estimation despite the presence of multipath interference

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A multipath composite wave signal is created as a simulated copy of the expected signal structure. This synthetic signal model incorporates both direct and multipath wave characteristics, allowing the system to compare actual reception signals against the modeled composite wave and extract accurate distance information through correlation analysis

Inventive Principle:

Principle #26Copying

2Device complexity

If simple propagation loss method is used for distance estimation, then device complexity remains low, but measurement precision deteriorates due to reception power fluctuation

Engineering Contradiction:

Improveprocessing complexityVSAvoiddistance estimation accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system replaces simple power-based distance estimation with signal correlation processing. Instead of relying on received power levels alone, the invention uses correlation between the reception signal and a simulated multipath composite wave signal, substituting a more sophisticated signal processing approach for the simpler but less accurate power measurement method

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enhances the accuracy of target distance estimation by considering both direct and multipath waves, providing precise distance measurements.

Implementation Method 1

a radio wave transmitted by a radio source and received by a radio wave detection device includes not only a direct wave propagated on a straight path from the radio source to the radio wave detection device but also multipath waves propagated from the radio source to the radio wave detection device via another path due to reflection or the like

Methodology Applied

Scientific EffectMultipath propagation: Reflection

Implementation Method 2

processing circuitry to generate a multipath composite wave signal that is a simulation signal of a composite wave of the direct wave and the multipath wave received by the reception antenna in a case where a provisional target distance, which is a provisional target distance from the radio wave detection device to the radio source, is set

Methodology Applied

Scientific EffectSignal simulation:

Implementation Method 3

to estimate the target distance from the radio wave detection device to the radio source on a basis of a correlation between the reception signals and the generated multipath composite wave signal

Methodology Applied

Scientific EffectCorrelation analysis:

Data Source

PatentUS12474457B2Target distance estimation device, radio wave detection device, and target distance estimation method

Publication Date: 2025.11.18 MITSUBISHI ELECTRIC CORP

AI summary

A target distance estimation device includes: a multipath composite wave signal generation unit that generates a multipath composite wave signal that is a simulation signal of a composite wave of a direct wave and a multipath wave received by a reception antenna in a case where a provisional target distance, which is a provisional target distance from a radio source to a radio wave detection device, is set; and a target distance estimation unit that estimates a target distance from the radio wave detection device to the radio source on the basis of a correlation between the reception signals and the multipath composite wave signal generated by the multipath composite wave signal generation unit.