Wireless Time Frequency Lock Loop Synchronization
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Solution Overview
Problem
Achieving high degree of frequency and time synchronization in wireless networks is challenging due to the difficulties in wirelessly recreating a phase-locked loop (PLL) system, as existing methods result in unreliable coarse-grained corrections and limited accuracy due to the imprecision and errors inherent in the wireless medium.
Innovation Solution
The Wireless Time and Frequency Lock Loop (WTFLL) system, which uses a digital closed-loop system that simultaneously monitors and adjusts time and frequency offsets using high-resolution interpolators and time stamp exchanges, allowing for accurate synchronization between wirelessly linked nodes by treating time and frequency synchronization as interrelated processes within a single coherent system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional wireless synchronization methods are used, then device connectivity is achieved, but synchronization accuracy deteriorates due to coarse-grained corrections and wireless medium imprecision
Solution Approach 1:
The patent segments the synchronization correction process into fine-grained incremental adjustments rather than coarse-grained corrections. The system divides the frequency and time offset corrections into small steps that can be precisely applied and monitored, allowing the slave device to gradually converge to the master device's timing and frequency with high precision while maintaining stability through controlled incremental changes.
Solution Approach 2:
The patent implements a closed-loop feedback system where the slave device continuously monitors the master device's timestamp and reference signal, computes time and frequency offsets, applies corrections, and verifies the results. This feedback mechanism allows the system to detect synchronization errors, apply precise corrections, and maintain stable locked state by continuously adjusting based on measured deviations.
2Measurement precision
If wired connections with known delays are used, then time and frequency synchronization is achieved, but wireless flexibility and mobility are lost
Solution Approach 1:
The patent introduces timestamp messages as an intermediary carrier that conveys precise timing information from the master device to the slave device through the wireless medium. The timestamp acts as a mediator that encapsulates reference time information, allowing the slave device to extract and compare timestamps to compute time offsets and frequency drifts, thereby achieving wired-level synchronization precision over wireless connections.
Solution Approach 2:
The patent replaces the mechanical wired connection system with a wireless electromagnetic signal-based system. Instead of using physical wires with known propagation delays, the system uses wireless transmission of timestamp messages and reference signals, combined with computational methods to determine and compensate for propagation delays and frequency offsets, achieving the same synchronization function without physical constraints.
3Reliability
If tight synchronization bounds are enforced, then signal lock is maintained, but system adaptability to frequency drift and Doppler effects is reduced
Solution Approach 1:
The patent implements dynamic synchronization bounds that adapt to changing conditions. The system continuously monitors frequency offsets and time drifts, and adjusts the correction parameters and tolerance levels based on the observed rate of change. This allows the system to maintain tight bounds when conditions are stable while accommodating larger variations when Doppler effects or frequency drift occur, ensuring both reliability and adaptability.
Solution Approach 2:
The patent changes the synchronization parameters dynamically based on operating conditions. The system adjusts frequency offset thresholds, time synchronization tolerances, and correction step sizes according to the measured frequency drift rate and signal quality. This parameter adaptation allows the system to maintain signal lock under varying conditions while remaining tolerant to Doppler effects and frequency variations that occur in wireless environments.
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
This approach enables a high degree of synchronization, maintaining time and frequency lock even in the presence of Doppler effects, improving accuracy and stability compared to traditional methods, and enabling applications such as synchronized cellular networks, precise positioning, and autonomous vehicle systems.
Implementation Method 1
adjusting the voltage controlled crystal oscillator based on the voltage generated by the summing junction to maintain frequency lock
Implementation Method 2
The output of the voltage controlled crystal oscillator is fed to a phase detector along with the master device reference signal
Implementation Method 3
The voltage output of the phase detector is fed to a low pass filter to generate a DC control voltage
Implementation Method 4
receiving, at a local device, a master device reference signal in the form of a modulated radio frequency (RF) signal from a master device
Data Source
AI summary
Systems and methods for wireless synchronization are disclosed. In one embodiment, a method is disclosed for synchronizing a slave device to a master device, comprising: receiving, at a local device, a master device reference signal in the form of a modulated radio frequency (RF) signal from a master device; receiving, at the local device, a master device time stamp from the master device; computing a time offset of the master device reference signal relative to a local reference oscillator signal of a local oscillator, using the master device time stamp; computing a frequency offset of the master device reference signal relative to the local reference oscillator signal; generating a local reference oscillator control signal based on the computed time offset and the computer frequency offset; and adjusting the local reference oscillator to maintain a frequency and time lock with the master device reference signal at the local device.