Narrow-band Wireless Ranging Protocol for Distance Estimation
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Solution Overview
Problem
Conventional wireless ranging systems face limitations such as high power consumption and complexity due to the use of ultra-wideband radios, and they are not suitable for applications requiring low power and simplicity, while also having limited range and resolution.
Innovation Solution
A multi-stage wireless ranging protocol that employs narrow-band radios, utilizing a data collection stage to gather multiple count samples, a processing stage to calculate and prune time-of-flight samples, and a reporting stage to determine distance, with features like frequency hopping for security and efficient power use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultra-wideband radios are used to achieve sufficient distance resolution, then measurement precision is improved, but use of energy increases and device complexity increases
Solution Approach 1:
The patent changes the bandwidth parameter from ultra-wideband to narrow-band, and compensates for the reduced single-measurement precision by increasing the number of measurements and using statistical processing. This allows achieving the required distance resolution with significantly lower power consumption narrow-band radios.
Solution Approach 2:
The patent divides the ranging process into multiple independent measurements rather than relying on a single high-precision measurement. By collecting multiple time-of-flight samples and processing them statistically, the system achieves the required distance resolution through aggregation of multiple low-precision measurements.
2Measurement precision
If ultra-wideband radios are used to achieve sufficient distance resolution, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the radio bandwidth parameter from ultra-wideband to narrow-band, which simplifies the radio hardware and reduces system complexity. The compensation for reduced single-measurement precision is achieved through software-based statistical processing of multiple measurements rather than through complex hardware.
Solution Approach 2:
The patent replaces the hardware-based precision approach (ultra-wideband radios with precise timing) with a software-based statistical processing approach. Multiple measurements are collected and processed using statistical methods to achieve the required distance resolution, substituting computational complexity for hardware complexity.
3Use of energy by moving object
If narrow-band radios are used to reduce power consumption, then use of energy is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent segments the ranging task into multiple independent measurements rather than relying on a single measurement. By collecting multiple time-of-flight samples from narrow-band radios and processing them statistically, the system achieves the required distance resolution that would be difficult to obtain from a single narrow-band measurement.
Solution Approach 2:
The patent performs more measurements than the minimum single measurement would provide, collecting excessive samples and then processing them statistically. This partial redundancy allows the system to achieve the required precision threshold while using low-power narrow-band radios, as the aggregate information from multiple measurements compensates for the lower precision of individual measurements.
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
The protocol achieves enhanced distance resolution and accuracy, improved security, and reduced power consumption, making it suitable for various applications using narrow-band wireless ranging systems.
Implementation Method 1
a radio at each device, with one device communicating an initial packet to the other device
Implementation Method 2
Based on the time at which the initial packet was transmitted and the time at which the return packet is received, the transmitting device can calculate a time-of-flight (ToF) of the packets and, based on the ToF, determine a distance (range) between the two devices
Data Source
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AI summary
A wireless ranging system generates, at a first device, a first plurality of counts, each of the first plurality of counts indicative of a transmit time of a corresponding packet, and further generates a second plurality of counts, each of the second plurality of counts indicative of a receive time of a corresponding packet. In response to a number of samples of the first plurality of counts exceeding a threshold, the system generates a plurality of timestamps based on the first plurality of counts and the second plurality of counts and generates a plurality of time-of-flight values based on the plurality of timestamps. Based on a combination of the plurality of the time-of-flight values, the wireless ranging system generates an effective time-of-flight value and identifies a distance between the first device and as second device based on the effective time-of-flight value.