Wireless Distance Measurement Using Accumulated Signal Delay
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Solution Overview
Problem
Existing wireless network technologies face challenges in accurately determining the location of client stations using signal propagation delay, particularly due to limitations in timing module resolution and potential inaccuracies in hardware, which affect the precision of distance calculations.
Innovation Solution
A wireless network device equipped with a RF transceiver module, a timing module, and a control module that transmits data frames and receives acknowledgement frames to calculate signal propagation delay, repeating the transmission sequence to accumulate delay periods and reduce errors, allowing for more accurate distance determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal propagation delay is used to determine distance between wireless devices, then location determination is enabled, but timing module resolution limitations cause measurement inaccuracies
Solution Approach 1:
The patent employs periodic transmission of data frames between wireless devices, where multiple frames are exchanged at regular intervals. By accumulating delay measurements from multiple periodic exchanges, the system effectively averages out timing errors and achieves higher measurement precision than a single measurement would provide, thereby overcoming the timing module resolution limitation.
Solution Approach 2:
The patent implements a feedback mechanism where acknowledgment frames are sent back from the receiving device to the transmitting device, confirming receipt and providing return delay information. This bidirectional feedback allows both devices to calculate round-trip delay and compensate for processing times, improving the accuracy of one-way propagation delay measurements despite hardware timing limitations.
2Reliability
If single data frame transmission is used for delay measurement, then measurement process is simple, but hardware inaccuracies cause calculation errors
Solution Approach 1:
The patent combines multiple individual delay measurements from successive data frame transmissions into a single accumulated delay value. By merging multiple measurements and averaging them, the system reduces the impact of random hardware inaccuracies and achieves more reliable distance determination, accepting the trade-off of increased measurement process complexity.
Solution Approach 2:
The patent performs preliminary calibration and synchronization actions before the actual distance measurement begins. Devices exchange synchronization frames and establish timing references in advance, which prepares the measurement system to compensate for hardware variations during the actual delay measurement phase, thereby improving reliability without significantly increasing operational complexity.
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 enhances the accuracy of distance calculations by overcoming resolution limitations and hardware inaccuracies, enabling precise location determination of client stations in wireless networks.
Implementation Method 1
a first RF transceiver module configured to (i) for a predetermined number of times, transmit a data frame to a second RF transceiver module
Implementation Method 2
a timing module configured to generate a timer value corresponding to an accumulated delay period, wherein the accumulated delay period corresponds to each of the respective delay periods
Data Source
AI summary
A first device including a timing module and a control module. The timing module is configured to calculate a first delay period between a first time a data frame is transmitted to a second device and a second time an acknowledgement frame is received from the second device. The timing module is further configured to calculate a second delay period between a third time the data frame is transmitted to the second device and a fourth time the acknowledgement frame is received from the second device. The control module is configured to calculate a total delay period corresponding to a sum of the first delay period and the second delay period and determine a distance between the first device and the second device based on the total delay and a number of times for the data frame to be transmitted to the second device.