Baseband-Coherent Dual-Tone Ranging for Wireless Distance
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Solution Overview
Problem
Existing ranging measurement techniques in multi-path environments, such as Bluetooth and WLAN, suffer from inaccuracies due to multi-path interference and are vulnerable to spoofing, with RTT being less accurate and RTT requiring complex oscillator coordination.
Innovation Solution
A method involving dual tone RF signals with baseband coherence between wireless devices to estimate one-way ranging and multi-path distances, using Discrete Fourier Transform (DFT) processing to compute complex gain responses, allowing for accurate distance and angle measurements without maintaining phase coherence on local oscillators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase-based ranging (RTP) is used to achieve accurate distance measurements, then measurement precision is improved, but the system becomes vulnerable to spoofing attacks and security reliability deteriorates
Solution Approach 1:
The patent combines phase-based ranging (RTP) and time-based ranging (RTT) measurements into a unified system. By merging these two measurement techniques, the system achieves both high accuracy from phase measurements and security robustness from time measurements, resolving the contradiction between precision and reliability
Solution Approach 2:
The system uses feedback by comparing phase-based and time-based measurements to detect potential spoofing attacks. When the two measurement results diverge beyond expected tolerances, the system can identify and reject spoofed signals, maintaining both accuracy and security
2Reliability
If Round Trip Time (RTT) measurements are used to improve security robustness, then reliability against spoofing is improved, but measurement precision deteriorates due to lower accuracy
Solution Approach 1:
The patent merges RTT and RTP measurements to compensate for RTT's lower precision. By combining the security robustness of RTT with the high accuracy of RTP, the system achieves both reliability and measurement precision that neither method could provide alone
3Measurement precision
If proprietary solutions maintain phase coherence on local oscillators to achieve accurate one-way ranging, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the phase coherence requirement from the local oscillator domain and relocates it to the baseband signal processing domain. By taking out the coherence requirement from hardware oscillators and implementing it in software/baseband processing, the system achieves accurate one-way ranging without complex oscillator coordination hardware
Data Source
AI summary
A one way ranging method estimates a distance between first and second wireless devices using a technique that involves exchanging dual tone RF signals between the devices and, at each of the first and second devices, maintaining “baseband coherence” between baseband signals carried by the RF signals transmitted and received by each respective device.