Two-Way Phase-Based Distance Estimation Using Packet Synchronized Data Capture
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Solution Overview
Problem
Conventional wireless ranging systems face challenges such as high power consumption, limited range, complexity, and insecurity due to the need for wideband technologies or multiple radios, and narrowband systems struggle with synchronization and accuracy issues, making them unsuitable for many applications.
Innovation Solution
A two-way phase-based distance estimation system that uses packet-synchronized data capture to calibrate and measure distances between wireless devices efficiently, employing a multi-stage protocol involving calibration, data collection, and phase vector processing to achieve precise distance estimation with reduced power consumption and improved security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wideband technologies (UWB or WLAN radios) are employed to achieve sufficient distance resolution, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent changes the fundamental parameter from wideband frequency hopping to narrowband continuous wave transmission at a single frequency. This allows achieving distance resolution through phase measurement of continuous signals rather than through wideband time-of-flight measurement, thereby reducing power consumption while maintaining measurement precision
Solution Approach 2:
The patent replaces the mechanical approach of using wideband radios with multiple frequency hops with a more efficient electromagnetic approach using narrowband continuous wave phase measurement. The phase-based measurement system substitutes the energy-intensive wideband transmission with lower-power narrowband phase comparison
2Measurement precision
If a large number of radios, antennas, or wireless nodes are employed to achieve higher distance resolution, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the distance measurement function into two simple components: a measuring device that transmits continuous wave signals and a reflecting device that reflects these signals. This segmentation allows achieving high distance resolution using only two simple devices rather than multiple complex radios or antennas
Solution Approach 2:
The patent uses phase comparison between transmitted and reflected signals as a simplified copy of the original signal characteristics. By measuring the phase difference of the reflected continuous wave signal, the system achieves high-resolution distance measurement without requiring multiple independent measurement channels
3Use of energy by moving object
If narrowband PDE systems are used to reduce power consumption, then energy efficiency is improved, but synchronization accuracy deteriorates due to time drift and signaling overhead
Solution Approach 1:
The patent employs periodic exchange of measurement packets between measuring and reflecting devices. These periodic packets contain synchronization information that continuously recalibrates the phase reference, thereby compensating for time drift while maintaining the energy efficiency of narrowband operation
Solution Approach 2:
The patent implements a feedback mechanism where the reflecting device sends back reflected continuous wave signals that encode phase information. The measuring device uses this feedback to continuously track and compensate for phase drift, maintaining synchronization accuracy without requiring excessive signaling overhead
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 system provides improved resolution, precision, faster measurement times, reduced power consumption, and enhanced security for wireless ranging, making it suitable for battery-powered devices and various applications.
Implementation Method 1
Phase-based Distance Estimation (PDE) is a technique developed in the defense and satellite domain for estimating the distance between objects by measuring the phase shift or difference (Δφ) between a measuring device (MD), which is the initiator and determines the need to estimate distance, and an active reflector device (RD)
Data Source
AI summary
A wireless ranging system (700) estimates a distance (703) between wireless devices (701, 702) by calibrating the devices through exchanging calibration packets (512, 524) to adjust transceiver settings for performing phase measurements at the wireless devices, and then transmitting a measurement packet (704) from a first wireless device to a second wireless device to synchronize the first and second wireless devices and to perform a two-way IQ data capture sequence at different carrier frequencies during processing of the measurement packet so that the first and second wireless devices each measure phase values for each of the plurality of different carrier frequencies, where the phase values at each of the first and second wireless devices are processed to generate a combined phase offset vector which is processed to determine a first estimated distance between the first and second wireless devices.