Phase-Coherent Wireless Ranging for RF Interference Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Real Time Location Systems (RTLS) suffer from inaccurate ranging due to phase shift and interference, leading to incorrect location estimation of tagged objects, especially in environments with multiple RF systems operating on the same frequencies.
Innovation Solution
Implement phase-coherent wireless signaling between beacons and tags using Constant Tone (CT) transmission, synchronized through local oscillator adjustment based on measured phase, to ensure accurate ranging data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wireless signaling is used for ranging between beacons and tags, then the system can operate with simple transmission protocols, but phase shift and interference cause inaccurate ranging measurements
Solution Approach 1:
The patent changes the parameter of phase coherence in wireless signaling by implementing synchronized local oscillators at both transmitting and receiving nodes. This synchronization maintains a constant phase relationship between transmitted and received signals, eliminating phase shift errors that normally degrade ranging accuracy. The constant tone transmission at a specific frequency further stabilizes the signal phase, enabling accurate phase-based ranging measurements despite the increased signaling complexity.
2Reliability
If multiple RF systems operate on the same frequencies in the environment, then spectrum utilization is efficient, but interference causes degraded ranging performance
Solution Approach 1:
The patent implements a feedback mechanism where the receiving node measures the phase of the received constant tone signal and uses this phase information to adjust its local oscillator. This feedback loop continuously compensates for phase variations caused by interference from other RF systems, maintaining accurate ranging measurements even in congested spectral environments. The handshaking protocol between transmitting and receiving nodes establishes and maintains this phase-synchronized state.
3Measurement precision
If phase-coherent signaling with local oscillator synchronization is implemented, then ranging accuracy is improved, but system complexity and synchronization requirements increase
Solution Approach 1:
The patent applies preliminary action by establishing phase synchronization between local oscillators before actual ranging measurements are performed. The handshaking protocol executes preliminary phase alignment and constant tone transmission, allowing the receiving node to measure and compensate for phase shifts in advance. This preliminary synchronization simplifies the subsequent ranging process, as the phase relationship is already established and stabilized.
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
Enhances ranging accuracy by compensating for phase shift, allowing precise geolocation of tagged objects even in interference-prone environments.
Implementation Method 1
sampling the complex baseband signal in in-phase and quadrature (IQ) format over a predetermined time to measure a phase of the complex baseband signal
Implementation Method 2
synchronize a frequency of a local oscillator (LO) thereof according to a frequency of the at least a first CT
Implementation Method 3
adjust a phase for the local oscillator (LO), based on the measured phase of the complex baseband signal, to synchronize a phase of at least a second constant tone (CT) to be transmitted from the second wireless communications node with the measured phase of the complex baseband signal
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided are a system and method for generating phase-coherent signaling when ranging between a transmitting node and a receiving node during wireless communication. Phase coherence is established in response to phase adjustment of a signal to be transmitted from the receiving node, in which such adjustment is commensurate with at least an amount of phase attributable to signaling transmitted by the transmitted node and received at the receiving node. Phase shift attributable to the signaling is compensated for upon receipt of the signaling at a tag in communication with the receiving node.