Trigger Frame MU Ranging for Indoor Location
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Solution Overview
Problem
Current wireless communication systems, such as WLANs, face challenges in accurately determining the location of communication devices within buildings or tunnels due to the limitations of GPS technology and the need for improved ranging measurement techniques.
Innovation Solution
A method and apparatus for performing ranging measurements using multi-user (MU) frame exchanges, where trigger frames are generated and transmitted to cause multiple communication devices to simultaneously transmit null data packets and feedback packets, allowing for the calculation of distances between devices using the received measurement feedback information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS technology is used for location determination, then outdoor positioning accuracy is improved, but it becomes ineffective in indoor or obstructed environments
Solution Approach 1:
The patent introduces WLAN infrastructure (access points and communication devices) as an intermediary system to enable location determination in environments where GPS is unavailable. Instead of relying directly on satellite signals, the system uses local WLAN transmissions and measurements as a mediator to achieve positioning functionality indoors and in obstructed areas.
2Measurement precision
If traditional WLAN ranging methods are used, then basic distance measurement is achieved, but measurement precision and efficiency are insufficient
Solution Approach 1:
The patent merges multiple ranging measurements into a single coordinated procedure. Multiple communication devices perform ranging measurements simultaneously by transmitting null data packets (NDPs) in response to a trigger frame, combining what would traditionally be separate sequential measurements into one efficient multi-user operation.
Solution Approach 2:
The access point sends a trigger frame in advance that coordinates the timing and content of NDP transmissions from multiple devices. This preliminary action synchronizes the ranging measurements, ensuring that all devices transmit at the correct time with appropriate preamble structures, thereby improving both precision and efficiency.
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 enables accurate location determination of communication devices by employing MU ranging measurement procedures, overcoming the limitations of GPS in indoor or obstructed environments and enhancing the precision of distance calculations.
Implementation Method 1
a distance between a first communication and a second communication device is determined by measuring a time of flight of WLAN transmissions between the first communication device and the second communication device
Data Source
AI summary
A first communication device generates and transmits a first trigger frame. One or more trigger type information fields of the first trigger frame are set to a first one or more respective values that indicates the first trigger frame is for: i) a multi-user (MU) ranging measurement procedure, and ii) causing multiple second communication devices to simultaneously transmit first null data packets (NDPs) as part of a first MU transmission associated with the MU ranging measurement procedure. The first communication device generates and transmits a second trigger frame. One or more trigger type information fields of the second trigger frame are set to a second one or more respective values that indicates the second trigger frame is for i) an MU ranging measurement procedure, and ii) causing the multiple second communication devices to simultaneously transmit feedback packets to the first communication device as part of a second MU transmission associated with the MU ranging measurement procedure.