Multi-Node Phase Ranging With Passive Listeners for NLOS Accuracy
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Solution Overview
Problem
Existing distance measurement techniques between wireless devices face challenges in accuracy and reliability, particularly under non-line-of-sight conditions and deep fading, and lack efficient methods to improve measurement precision without increasing energy consumption or communication overhead.
Innovation Solution
A multi-node system involving an initiator, reflector, and passive listeners performs phase-based ranging using continuous wave signals, where passive nodes observe and compute phase measurements to enhance distance estimation accuracy without additional communication, leveraging known distances and phase relationships to determine spatial positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phase-based ranging is performed between two wireless devices, then distance measurement capability is provided, but measurement accuracy deteriorates under non-line-of-sight conditions and deep fading
Solution Approach 1:
The patent introduces passive listener nodes as intermediaries that observe and measure phase information of continuous wave signals exchanged between the initiator and reflector. These passive nodes serve as mediators that capture additional phase measurement data without actively participating in the two-way signal exchange, thereby improving measurement reliability under non-line-of-sight conditions without adding communication overhead
Solution Approach 2:
The patent combines phase measurements from multiple sources (direct measurement between initiator and reflector, and passive observations from listener nodes) into a unified distance estimation process. By merging multiple phase measurement datasets, the system achieves more robust and accurate distance measurements that overcome the limitations of single-pair measurements
2Measurement precision
If additional measurement nodes are added to improve accuracy, then measurement precision improves, but device complexity and energy consumption increase
Solution Approach 1:
Passive listener nodes are introduced as intermediaries that only observe and measure phase information without actively transmitting or managing the ranging protocol. This mediator role allows multiple measurement points to be added to improve precision while keeping each node's functionality simple and energy-efficient
Solution Approach 2:
The passive listener nodes perform self-service by autonomously measuring phase information of the continuous wave signals they receive and reporting their measurements to the initiator. Each passive node independently contributes its local phase measurements without requiring coordination or management from other nodes, simplifying the overall system architecture
3Measurement precision
If passive nodes are used to observe and compute phase measurements, then measurement accuracy improves, but communication overhead increases
Solution Approach 1:
The patent extracts only the essential phase measurement data from the passive listener nodes and transmits this extracted information to the initiator. By taking out only the critical phase values rather than transmitting complete measurement datasets or raw signal information, the system achieves high measurement precision while minimizing communication overhead
Solution Approach 2:
The passive listener nodes create simplified copies of the phase information they observe, reporting only the phase measurement values to the initiator rather than transmitting complete signal waveforms or detailed measurement metadata. This copying approach enables accurate phase measurement while keeping communication efficient
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 significantly improves distance measurement accuracy and security by utilizing passive nodes to supplement measurements, reducing energy consumption and communication overhead while enhancing resistance to phase attacks.
Implementation Method 1
receiving a first continuous wave signal from the first wireless device and receiving a second continuous wave signal from the second device
Implementation Method 2
generate phase data based on receiving the first continuous wave signal and the second continuous wave signal
Data Source
AI summary
A system includes an initiator, a reflector, and one or more passive nodes. The initiator and the reflector may participate in a channel sounding procedure, and the one or more passive nodes may listen in on the channel sounding procedure. The passive nodes may measure phase offset relative to their local oscillators and then transmit phase data to the initiator, the reflector, and/or a control node separate from the initiator and the reflector. The device receiving the phase data may then use that phase data to calculate distance and, from the distance, calculate spatial position. The system may be used to calculate a position of the initiator or of the reflector.