Null Data Packet Timing for Wireless Distance Measurement
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Solution Overview
Problem
Current location determination techniques for wireless devices, such as those using GPS and cell tower signals, are ineffective indoors due to weak signal strength, and timing measurement frame methods are limited in accuracy and processing-intensive, necessitating enhanced methods for precise distance measurement between wireless devices.
Innovation Solution
A method involving the exchange of Null Data Packet frames between wireless devices to determine distance, where an initiating Station sends a timing measurement request, receives confirmation, and calculates distance based on timing measurements of uplink and downlink Null Data Packet frames, including time-of-departure and time-of-arrival, using supported frame formats and bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing measurement frames are used to determine device location, then location determination is possible without beacons, but measurement accuracy is limited and processing is intensive
Solution Approach 1:
The patent segments the location determination process into multiple independent timing measurements (t1, t2, t3, t4) of separate Null Data Packet frames exchanged between devices. By dividing the measurement into multiple discrete timing events rather than using a single complex beacon signal, the system achieves higher accuracy through accumulated precision while maintaining reliability without requiring multiple beacons.
2Area of stationary object
If multiple beacons are deployed to cover a given area, then location determination coverage is improved, but system cost and complexity increase
Solution Approach 1:
The patent makes existing Wi-Fi infrastructure universal by enabling regular access points and stations to perform location determination functions through Null Data Packet exchanges. Instead of requiring specialized beacon devices, any Wi-Fi equipped device can participate in timing measurements, allowing existing infrastructure to serve dual purposes: data communication and location determination, thereby expanding coverage without increasing device complexity.
3Ease of manufacture
If timing measurement frames are used instead of beacons, then system cost is reduced, but measurement accuracy is limited
Solution Approach 1:
The patent changes the measurement parameters by using Null Data Packet frames with precise timing stamps (t1, t2, t3, t4) exchanged between devices. By modifying the frame type to NDP and utilizing detailed timing parameters for each packet exchange, the system achieves high measurement precision while maintaining the cost advantage of using existing Wi-Fi infrastructure without additional beacons or specialized hardware.
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 method provides accurate and efficient distance measurement between wireless devices, improving location determination within structures where traditional methods fail, leveraging existing Wi-Fi infrastructure without the need for additional beacons, and supporting applications like hyperlocal marketing and equipment tracking.
Implementation Method 1
The initiating Station (STA) then determines a distance between the initiating Station (STA) and the responding Station (STA) based on the one or more timing measurements of the uplink and downlink Null Data Packet (NDP) frames
Data Source
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AI summary
A method of determining a distance between mobile wireless devices can include determining a format and bandwidth supported by an initiating Station (STA) and a responding Station (STA) and exchanging one or more sets of Null Data Packet (NDP) frames between the initiating Station (STA) and the responding Station (STA) using the determined format and bandwidth. The distance between the initiating Station (STA) and the responding Station (STA) can then be determined based on timing measurements of the one or more sets of Null Data Packet (NDP) frames exchanged between the initiating Station (STA) and the responding Station (STA).