Passive FTM Positioning Using Single-Burst Timing Exchanges
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Solution Overview
Problem
Existing position determination techniques for mobile devices face issues of privacy compromise, high power consumption, and scalability challenges due to active signal transmission and reception, which are not effectively addressed by current methods.
Innovation Solution
A passive positioning technique using a single burst Fine Timing Measurement (FTM) session is employed, where an observing station listens to FTM messages exchanged between two messaging stations, determining its position based on arrival and transmission-related times, without actively participating in these exchanges, and utilizing a modified FTM frame format for deterministic scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active transmission and reception of positioning signals is performed, then position determination can be achieved, but privacy is compromised
Solution Approach 1:
The patent inverts the traditional active positioning approach by implementing passive positioning. Instead of the mobile device actively transmitting and receiving positioning signals, the mobile device passively receives positioning signals from access points while access points transmit signals that can be detected by multiple devices. This inversion allows position determination without the mobile device actively participating in signal exchange, thereby preserving privacy.
Solution Approach 2:
The patent introduces access points as intermediaries in the positioning process. Rather than mobile devices directly exchanging positioning signals, access points serve as mediators that transmit signals detectable by multiple mobile devices. The positioning calculation is then performed by a server or the mobile device itself based on received signal timing information, with the access points acting as intermediary signal sources that enable positioning without direct device-to-device signal exchange.
2Measurement precision
If active transmission and reception of positioning signals is performed, then position determination can be achieved, but power consumption increases
Solution Approach 1:
The patent inverts the traditional active positioning approach by implementing passive positioning. Instead of the mobile device actively transmitting and receiving positioning signals, the mobile device passively receives positioning signals from access points while access points transmit signals that can be detected by multiple devices. This inversion allows position determination without the mobile device actively participating in signal exchange, thereby preserving privacy.
Solution Approach 2:
The patent enables access points to serve multiple functions simultaneously. Access points transmit positioning signals as part of their normal operation, and these same signals are used by multiple mobile devices for positioning without requiring additional dedicated signaling resources. The infrastructure serves itself by utilizing existing signal transmissions for multiple purposes including both data communication and positioning, thereby avoiding additional power consumption at the mobile device end.
3Measurement precision
If a large number of mobile devices perform active positioning simultaneously, then position determination is available to all devices, but system scalability is limited
Solution Approach 1:
The patent makes the positioning system universal by enabling a single set of access point transmissions to serve multiple mobile devices simultaneously. The access points transmit positioning signals that can be detected by any number of mobile devices in range, and a central server coordinates positioning calculations for all devices using the same signal infrastructure. This multi-functional approach allows the system to scale to large numbers of devices without requiring proportional increases in signaling resources or system complexity.
Solution Approach 2:
The patent introduces access points as intermediaries in the positioning process. Rather than mobile devices directly exchanging positioning signals, access points serve as mediators that transmit signals detectable by multiple mobile devices. The positioning calculation is then performed by a server or the mobile device itself based on received signal timing information, with the access points acting as intermediary signal sources that enable positioning without direct device-to-device signal exchange.
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 privacy, reduces power consumption, and improves scalability by allowing numerous devices to perform position estimation simultaneously with minimal impact on messaging stations, while maintaining accurate positioning through hyperbolic curve intersection.
Implementation Method 1
determining a first time of arrival corresponding to a time at which the first FTM message arrives at the observing station... determining a second time of arrival corresponding to a time at which the second FTM message arrives at the observing station... obtaining a first transmission-related time associated with transmission or reception of the first FTM message... obtaining a second transmission-related time associated with transmission or reception of the second FTM message
Data Source
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AI summary
Techniques for estimating a position of an observing station are disclosed based on capturing, at the observing station, a first and a second FTM message exchanged between a first messaging station and a second messaging station. At the observing station, a first time of arrival of the first FTM message and a second time of arrival of the second FTM message may be determined. Based on contents of one or more FTM messages, a first transmission-related time associated with the first FTM message and a second transmission-related time associated with the second FTM message may be obtained. The position of the observing station may be estimated based on (1) a position of the first messaging station, (2) a position of the second messaging station, (3) the first time of arrival, (4) the second time of arrival, (5) the first transmission-related time, and (6) the second transmission-related time.