Wireless Propagation Time Determination Using Local TX-TX and RX-RX Intervals
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Solution Overview
Problem
Existing methods for determining the propagation time of wireless transmissions between two devices, such as those used in keyless vehicle access systems, face inaccuracies due to variations in quartz oscillator accuracy and require additional communication efforts, especially in limited capacity channels.
Innovation Solution
A method that compensates for these inaccuracies by using TX-TX and RX-RX time differences to determine the propagation time, reducing the reliance on RX-TX and TX-RX measurements, and potentially eliminating the need for additional communication by using pre-defined or locally calculated time intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RX-TX and TX-RX time measurements are used to compensate for quartz oscillator variations, then oscillator tolerance is mitigated, but measurement accuracy decreases due to the complexity of receive event measurement
Solution Approach 1:
The patent extracts and eliminates the problematic RX-TX and TX-RX time measurements from the propagation time calculation. By using only TX-TX and RX-RX time differences, the method removes the source of measurement complexity and tolerance issues while retaining the ability to compensate for oscillator variations through the ratio of these time differences.
Solution Approach 2:
Instead of measuring TX-RX and RX-TX time intervals as in conventional methods, the patent inverts the approach by measuring TX-TX and RX-RX time intervals. This inversion allows both devices to measure events of the same type (transmit or receive) locally, avoiding the need to measure across devices which introduces complexity and tolerance issues.
2Reliability
If DS-TWR is used to mitigate quartz oscillator variations, then oscillator tolerance is compensated, but communication overhead increases due to additional information exchange
Solution Approach 1:
The patent extracts and removes the additional information exchange requirement from the DS-TWR protocol. By enabling each device to calculate propagation time independently using only locally measured TX-TX and RX-RX time differences, the method eliminates the need for devices to exchange additional numerical values, thereby reducing communication overhead while maintaining oscillator tolerance compensation.
Solution Approach 2:
Each wireless communication device performs the propagation time calculation independently using its own local measurements. Device A calculates propagation time using its measured T1 and received T2, while Device B calculates using its measured T3 and received T4. This self-service approach eliminates the need for additional communication rounds to share measurement data.
3Measurement precision
If additional numerical values are transmitted for crystal oscillation compensation in DS-TWR, then oscillator accuracy is improved, but communication efficiency decreases in limited capacity channels
Solution Approach 1:
The patent extracts and eliminates the transmission of additional numerical values for crystal oscillation compensation. By enabling each device to perform local calculations using the ratio of TX-TX and RX-RX time differences, the method removes the need for additional data transmission, thereby maintaining measurement precision while improving communication efficiency in limited capacity channels.
Data Source
AI summary
Methods and devices related to determining a propagation time of wireless transmissions between wireless communication devices are provided. A propagation time of wireless transmissions between a first wireless communication device and a second wireless communication device is determined. The determining is based on a roundtrip time of a wireless transmission exchange between the first wireless communication device and the second wireless communication device, a reply time of the wireless transmission exchange, and on the first time interval and the second time interval. The first time interval is a time interval between a first transmit event at the first wireless communication device and a second transmit event at the first wireless communication device. The second time interval is a time interval between a first receive event at the second wireless communication device and a second receive event at the second wireless communication device.