Passive Wireless Tag Positioning via Base Station Timestamps
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Solution Overview
Problem
Existing location determination methods using wireless signals often require devices to transmit messages, which can lead to energy consumption and interference issues, and may not support a large number of tags without synchronization of base stations.
Innovation Solution
An apparatus and method that enable tags to determine their location by receiving messages from a master base station and non-master base stations, using timestamps to calculate time differences and ratios between message transmissions, allowing location determination without transmitting messages, utilizing ultra-wide band wireless interfaces and known base station locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If tags transmit messages for location determination, then location accuracy is improved, but energy consumption increases
Solution Approach 1:
Instead of having tags transmit messages to determine location, the patent inverts the approach by having tags receive messages from base stations. The base stations transmit initial messages, response messages, and data messages containing timing information, allowing tags to calculate their location passively without transmitting, thus reducing energy consumption while maintaining location determination capability
Solution Approach 2:
The system enables tags to determine their own location autonomously by processing received messages from base stations. Each tag uses the timing information in received messages to calculate time differences and determine its position without requiring active transmission or external assistance, making the tagging device self-sufficient for location determination
2Loss of information
If tags transmit messages for location determination, then location information is obtained, but interference increases
Solution Approach 1:
The patent extracts the transmission function from tags and relocates it to base stations. By removing the transmitting capability from tags and concentrating transmission at base stations, the system eliminates interference generated by numerous tags transmitting simultaneously, while still obtaining location information through the received timing data at each tag
3Measurement precision
If base stations are synchronized for TDOA positioning, then location accuracy is improved, but system complexity increases
Solution Approach 1:
The patent introduces an intermediary approach where base stations transmit messages with embedded timing information (timestamps indicating transmission times) rather than requiring direct synchronization between base stations. Tags use these timestamps to calculate time differences relative to their own reception times, eliminating the need for complex inter-base-station synchronization infrastructure while maintaining positioning accuracy
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 multiple tags to determine their location efficiently by listening to wireless messages, reducing energy consumption and interference, and supporting a large number of tags without requiring base station synchronization, while providing accurate location estimates.
Implementation Method 1
determine: based on the received wireless messages, for the master base station and each non-master base station, a time difference of arrival from the apparatus, and based at least partly on the determined time difference of arrival, a location of the apparatus
Data Source
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AI summary
According to an example aspect of the present invention, there is provided an apparatus comprising a receiver (110, 120, 130) configured to receive at least the following wireless messages: an initial message (100A) from a master base station (150), at least one response message from each of at least two non-master base stations (160, 170, 180) and a data message from the master base station, and at least one processing core configured to determine, based on the received wireless messages, for the master base station and each non-master base station, a time difference of arrival from the apparatus, and based at least partly on the determined time difference of arrival, a location of the apparatus.