Wireless Distance Estimation via Enhanced ACK Timing
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Solution Overview
Problem
Current indoor navigation methods, such as Time-of-Flight (ToF) measurement, face significant scheduling, medium, and storage overheads, necessitating more efficient approaches to estimate distances between stations in indoor environments.
Innovation Solution
The method involves wirelessly transmitting and receiving message frames, including fine timing measurement (FTM) frames, and calculating distances using the measured departure and arrival times of these frames, with acknowledgement (Ack) frames containing arrival and departure times, to determine station distances efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Time-of-Flight measurement method is used for indoor navigation, then distance between stations can be calculated, but scheduling overhead and medium overhead increase significantly
Solution Approach 1:
The patent combines the distance measurement function with the existing acknowledgment frame structure. The ACK frame that is already part of the communication protocol is enhanced to include timing information (arrival time and departure time), merging the measurement function with the existing acknowledgment mechanism rather than requiring separate measurement procedures.
Solution Approach 2:
The acknowledgment frame is given multiple functions: it serves both as a standard protocol acknowledgment and as a carrier for timing measurement data. This multi-functionality eliminates the need for separate measurement messages, reducing scheduling overhead while maintaining measurement capability.
2Measurement precision
If Time-of-Flight measurement method is used for indoor navigation, then distance between stations can be calculated, but storage overhead increases significantly
Solution Approach 1:
The patent extracts only the essential timing information (arrival time and departure time) needed for distance calculation and embeds it in the ACK frame. This selective extraction of necessary data minimizes storage requirements while maintaining measurement accuracy, avoiding the need to store complete measurement sequences or additional metadata.
3Productivity
If acknowledgment frames include arrival and departure times, then distance estimation becomes more efficient, but frame size increases
Solution Approach 1:
The timing information is merged into the existing ACK frame structure rather than being transmitted in separate messages. This approach increases frame size only minimally (by the bytes required for timing data) while achieving efficient distance estimation, as the ACK frame is already part of the standard communication 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 reduces overheads by providing a more efficient method for estimating distances between stations, enhancing indoor navigation by minimizing scheduling and storage requirements while improving response times and bandwidth utilization.
Implementation Method 1
The ToF may be defined as the time it takes a signal to propagate from a first station, e.g., a user ('client') mobile device, to a second station, e.g., an access point (AP), and back to the first station. A distance between the first and second stations may be calculated based on the ToF value.
Data Source
AI summary
A method of determining a station distance includes a station transmitting a first message including a message frame; the station measuring a first departure time of the message frame; the station receiving a second message in response to the first message, the second message including an acknowledgement (Ack) frame including a first arrival time at which the message frame arrived and a second departure time at which the Ack frame departed; the station measuring a second arrival time at which the Ack frame arrived; and the station determining the station distance from the first departure time, the second arrival time, the received first arrival time, and the received second departure time.