One-Way Time-of-Flight Localization Using Sonic and Electromagnetic Signals
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Solution Overview
Problem
Existing two-way time-of-flight techniques for mobile ad hoc networks require precise clock sources, are prone to errors due to low reflection areas, multi-path issues, and 1/r^4 losses, and are challenging for uncooperative nodes, limiting their effectiveness in coherent array formation and distance measurement accuracy.
Innovation Solution
Implementing one-way time-of-flight localization using sonic and electromagnetic signals, where a sonic signal travels between nodes, and an electromagnetic signal is used to start or stop a timer, allowing for distance calculation without clock synchronization and avoiding reflection-related problems, enabling accurate positioning and timing synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-way time-of-flight techniques are used for distance measurement, then distance can be calculated, but precise clock synchronization is required and errors occur due to reflection issues
Solution Approach 1:
The patent introduces a passive reflector as an intermediary element that enables distance measurement without requiring active participation or precise clock synchronization from the target node. The reflector passively bounces the acoustic signal back to the source node, allowing the source node to calculate distance based on the round-trip time of the acoustic signal alone, eliminating the need for clock synchronization between source and target nodes
Solution Approach 2:
Instead of using electromagnetic signals that require precise timing and clock synchronization, the patent inverts the approach by using acoustic signals which travel much slower and can be measured with lower precision clocks. The method inverts the conventional radar approach by using acoustic waves rather than electromagnetic waves for the time-of-flight measurement
2Speed
If electromagnetic signals are used for communication, then high-speed data transmission is achieved, but 1/r^4 losses and multi-path issues occur
Solution Approach 1:
The patent replaces electromagnetic field-based communication with acoustic wave-based communication. By using acoustic waves that propagate through the medium rather than electromagnetic waves, the system avoids the 1/r^4 path loss and multi-path interference problems inherent in electromagnetic signal propagation, particularly in indoor environments
3Measurement precision
If two-way time-of-flight methods are used, then distance measurement is possible, but uncooperative nodes cannot be localized
Solution Approach 1:
The passive reflector acts as a mediator that enables measurement without requiring the target node to be cooperative. The reflector passively returns the acoustic signal without needing to process, timestamp, or respond actively, allowing the source node to measure distance to nodes that do not participate in the communication protocol
Solution Approach 2:
The system uses the existing acoustic reflections in the environment as a resource for measurement. Instead of requiring active participation from target nodes, the method utilizes the natural acoustic properties of the environment and passive reflectors to enable distance measurement and localization
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 allows for accurate distance measurement between nodes without precise clock synchronization, reduces errors, and supports coherent array formation, enabling high-gain synthetic aperture antennas and improved communication capabilities at lower costs compared to conventional methods.
Implementation Method 1
an electromagnetic signal is used to start or stop a timer
Implementation Method 2
a sonic signal travels between nodes
Implementation Method 3
using the electromagnetic signal to one of start or stop a timer and using the sonic signal to another of stop or start the timer
Data Source
AI summary
A method includes communicating first and second signals between a first node and a second node, where the first signal includes a sonic signal and the second signal includes an electromagnetic signal. The method also includes using the electromagnetic signal to one of start or stop a timer and using the sonic signal to another of stop or start the timer. The method further includes identifying a one-way time-of-flight associated with the sonic signal traveling between the first and second nodes using the timer. The one-way time-of-flight associated with the sonic signal is indicative of a distance between the nodes.