Receiver Null Point Scanning for Direct Wave Angle Estimation

Solution Overview

Problem

In multipath environments where delay waves with short delay times overlap with direct waves, existing methods struggle to accurately estimate the arrival angle of the direct wave, leading to degraded estimation accuracy, especially when using a small number of antenna elements.

Innovation Solution

A receiver apparatus and method that utilize a null point scanning technique to separate delay waves by generating and synthesizing electric-power delay profiles, creating a two-dimensional map of delay times and arrival angles, and estimating the arrival angle of the direct wave component with the shortest delay time and largest electric power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the MUSIC method or ESPRIT method is used to measure arrival angles, then the measurement precision is improved, but the device complexity increases because the antenna array must include antenna elements equal to the maximum number of assumed incoming waves

Engineering Contradiction:

Improvearrival angle measurement precisionVSAvoidantenna array size

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the measurement process into two stages: first using a small number of antenna elements to obtain a rough arrival angle estimate, then using this estimate to guide a more precise measurement process. This segmentation allows achieving high measurement precision without requiring a large antenna array, thus resolving the contradiction between measurement precision and device complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary action by first obtaining a rough arrival angle estimate before conducting the final precise measurement. This preliminary estimate is used to configure the measurement process, enabling accurate arrival angle measurement with fewer antenna elements than traditionally required, thereby reducing device complexity while maintaining measurement precision

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If the number of antenna elements is reduced, then the device complexity is decreased, but the measurement precision deteriorates because existing methods can only accurately measure up to N waves with N antenna elements

Engineering Contradiction:

Improveantenna array sizeVSAvoidarrival angle measurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the measurement task into sequential stages: an initial rough estimation phase followed by a refined measurement phase. This segmentation enables the system to achieve high measurement precision with a small number of antenna elements, overcoming the limitation that traditional methods require N antenna elements for N incoming waves

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a temporal dimension to the measurement process by performing measurements at different stages with different levels of precision. The rough estimate obtained first is then used to guide a more precise measurement, effectively adding a time-based dimension that allows accurate measurement with fewer antenna elements, thus resolving the contradiction between device complexity and measurement precision

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Loss of information

If delay waves with short delay times overlap with direct waves, then the loss of information increases, but the device complexity remains unchanged

Engineering Contradiction:

Improveseparation of direct wave and delay waveVSAvoidsignal processing complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent performs preliminary action by first obtaining a rough arrival angle estimate before conducting the final precise measurement. This preliminary estimate is used to configure the measurement process, enabling accurate arrival angle measurement with fewer antenna elements than traditionally required, thereby reducing device complexity while maintaining measurement precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the measurement process into two stages: first using a small number of antenna elements to obtain a rough arrival angle estimate, then using this estimate to guide a more precise measurement process. This segmentation allows achieving high measurement precision without requiring a large antenna array, thus resolving the contradiction between measurement precision and device complexity

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10158436B2Receiver apparatus and reception method

Publication Date: 2018.12.18 MITSUBISHI ELECTRIC CORP

AI summary

A receiver apparatus 1 estimates a plurality of first electric-power delay profiles from a plurality of digital signals based on signals received via an array antenna; generates a synthesized electric-power delay profile q(m, l) by synthesizing these; generates an array process signal y(k) from the plurality of digital signals; estimates a second electric-power delay profile from the array process signal; generates a difference electric-power delay profile d(m, l) by subtracting the second electric-power delay profile from the synthesized electric-power delay profile; and creates a two-dimensional map indicating a relationship between delay times and arrival angles of incoming waves, on the basis of the difference electric-power delay profile and a direction of a null point. The receiver apparatus 1 changes the direction of the null point and repeats the above process, and estimates an arrival angle θ1 of a direct wave on the basis of the two-dimensional map.