Cooperative Relay Network Positioning with Time-of-Arrival

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Solution Overview

Problem

Conventional real-time location systems (RTLS) face challenges with high energy consumption and deployment costs, particularly in two-way time-of-arrival (TW-ToA) systems, which limit their scalability and commercial viability due to high traffic volume requirements and energy consumption.

Innovation Solution

A positioning and tracking system that reduces energy consumption by using a cooperative wireless relay network with a primary node and secondary nodes to perform two-way ranging, combining time-of-arrival information to achieve 2D position estimates with as few as three transmissions, thereby improving accuracy and reducing overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If two-way time-of-arrival (TW-ToA) systems are used for positioning, then positioning accuracy is improved, but energy consumption and traffic volume increase significantly

Engineering Contradiction:

Improvepositioning accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent combines TOA measurements from multiple anchor nodes with TDOA measurements from relay nodes into a unified positioning framework. This merging allows the system to achieve accurate 2D positioning by integrating information from different measurement types, reducing the need for excessive transmissions while maintaining precision.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The positioning process is segmented into two distinct phases: a calibration phase where reference positions are established using TOA measurements, and a tracking phase where TDOA measurements from relay nodes are used for continuous positioning. This segmentation reduces overall energy consumption by optimizing the frequency and type of measurements in each phase.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If TW-ToA systems are deployed for indoor positioning, then positioning accuracy is improved, but deployment cost increases

Engineering Contradiction:

Improvepositioning accuracyVSAvoiddeployment cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Relay nodes in the system serve multiple functions: they act as both communication relays for normal network operations and as positioning sensors for TDOA measurements. This multi-functionality reduces deployment costs by utilizing existing infrastructure nodes for positioning purposes without requiring dedicated expensive hardware.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the existing communication infrastructure and node transmissions for self-calibration and positioning. Nodes automatically perform calibration procedures and exchange positioning information without requiring external calibration equipment or manual configuration, reducing deployment and maintenance costs.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If conventional TW-ToA systems are used, then positioning capability is achieved, but scalability is limited due to high traffic volume requirements

Engineering Contradiction:

Improvepositioning capabilityVSAvoidscalability

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system implements periodic calibration at reference positions followed by continuous tracking using TDOA measurements. This periodic action pattern allows the system to scale efficiently by performing intensive measurements only when necessary (during calibration) and using lighter-weight measurements for continuous tracking, reducing overall traffic volume.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Relay nodes act as intermediaries that capture and forward positioning information from multiple anchor nodes simultaneously. This intermediary function enables the system to scale to more nodes without proportionally increasing traffic volume, as relay nodes aggregate and process information locally before forwarding to the position solver.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the accuracy of position estimation while minimizing energy consumption and deployment costs, enabling efficient tracking of targets with improved scalability compared to conventional TW-ToA systems.

Implementation Method 1

measure time difference of arrival (TDoA) of radio signals

Methodology Applied

Scientific EffectTime of Flight: Time of Flight

Data Source

PatentUS8259699B2Method and system for target positioning and tracking in cooperative relay networks

Publication Date: 2012.09.04 MITSUBISHI ELECTRIC RESEARCH LABORATORIES INC

AI summary

A method and system locates a position of a transceiver in a cooperative relay network of nodes. A primary node broadcasts a range request (RREQ) message. A target node, in response to receiving the RREQ message, broadcasts a range reply (RREP) message, wherein the RREP message includes a time difference between receiving the RREQ message and broadcasting the RREP message. A secondary node, in response to receiving the RREQ message and the RREP message, broadcasts a range data (RDAT) message, wherein the RDAT message includes a time difference between receiving the RREQ message and the RREP message. Then, a position solver can determine a location of the target node based on the time differences in the RREP message and the RDAT message.