Wireless Terminal Position Estimation Using Signal Power

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Solution Overview

Problem

In densely populated wireless communication networks, existing position estimation methods face challenges in accurately estimating the position of wireless terminals due to limited communication range and difficulty in correcting distance relational coefficients, especially when nodes are closely distributed.

Innovation Solution

A position estimation device and method that select and reselect wireless terminals, calculate distances based on radio signal power, and convert relative positions to absolute positions using a selector, distance calculator, relative position calculator, and absolute position converter, improving accuracy by averaging and weighting absolute positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If nodes are densely distributed in a narrow range, then network coverage is improved, but position estimation accuracy deteriorates due to difficulty in correcting distance relational coefficients

Engineering Contradiction:

Improvenetwork coverage areaVSAvoidposition estimation accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by iteratively reselecting subsets of wireless terminals multiple times rather than using a static selection. The selector reselects N wireless terminals from M wireless terminals in repeated iterations, allowing the system to adapt to the dense distribution environment and improve position estimation accuracy through dynamic adjustment of the terminal subset used for calculation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of terminal selection by replacing at least one wireless terminal between iterations. This parameter change allows the system to explore different combinations of terminals and find optimal subsets for position estimation, thereby improving accuracy in dense network conditions where traditional methods fail.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If hop count is used to correct distance relational coefficient, then position estimation is simplified, but accuracy deteriorates when most packets reach in one hop

Engineering Contradiction:

Improveposition estimation simplicityVSAvoiddistance relational coefficient accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary mechanism by using multiple wireless terminals as mediators in the position estimation process. Instead of relying solely on hop count from a single path, the system uses distance calculations from multiple terminals (N out of M) to triangulate position, providing more accurate distance relational coefficients even when direct one-hop connections dominate the network.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent substitutes the mechanical hop-count-based correction method with a radio signal power-based distance calculation system. By measuring received signal strength and converting it to distance estimates, the system replaces the discrete hop-count mechanism with continuous distance measurements from multiple terminals, improving accuracy in dense networks where hop count provides insufficient differentiation.

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 wireless terminal position estimation in densely distributed networks by iteratively selecting and replacing wireless terminals, calculating distances, and converting relative to absolute positions, thereby improving positional accuracy.

Implementation Method 1

calculate distances among wireless terminals in a group consisting of a parent wireless terminal and the N wireless terminals based on information on power of radio signals of packets transmitted and received among wireless terminals in the group

Methodology Applied

Scientific EffectRadio signal power attenuation: Absorption (EM radiation)

Data Source

PatentUS11070948B2Position estimation device and position estimation method

Publication Date: 2021.07.20 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

A position estimation device includes: a selector configured to select N wireless terminals and reselect N wireless terminals from M wireless terminals; a distance calculator configured to calculate distances among wireless terminals in a group consisting of a parent wireless terminal and the N wireless terminals based on information on power of radio signals of packets transmitted and received; a relative position calculator configured to calculate relative positions of the M wireless terminals based on the distances among the wireless terminals in the group for the N wireless terminals selected and reselected; and an absolute position converter configured to convert a relative position of a child wireless terminal into an absolute positon of the child wireless terminal based on the relative positions of the M wireless terminals and absolute positions of at least three of the M wireless terminals where the absolute positions are known.