Phase Offset Compensation in Dynamic Frequency Deviation Schemes
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Solution Overview
Problem
Digital coherent receivers face errors and potential communication interruptions due to phase offsets when dynamically changing frequency deviation compensation, especially in non-differential coding modes.
Innovation Solution
A frequency deviation compensation scheme that includes phase offset compensation, calculating and adjusting for phase offsets caused by changes in frequency deviation compensation, using phase rotation to correct these offsets in both frequency and time domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency deviation compensation amount is dynamically changed, then communication system can adapt to frequency fluctuations, but phase offsets occur causing errors and communication interruptions
Solution Approach 1:
The patent calculates and compensates for phase offsets in advance before they cause errors. The phase offset calculation unit computes the phase offset based on the changed frequency deviation compensation amount, and the phase offset compensation unit applies compensation before the phase offset affects communication reliability.
Solution Approach 2:
The patent implements a feedback mechanism where the phase offset calculation unit continuously monitors changes in frequency deviation compensation amounts and calculates corresponding phase offsets. This feedback loop ensures that phase offsets are dynamically compensated to maintain communication stability during frequency fluctuations.
2Manufacturing precision
If overlap-type FFT and IFFT are used to prevent discontinuous points, then waveform distortion is compensated, but phase offsets still occur when frequency deviation compensation changes dynamically
Solution Approach 1:
The patent introduces a phase offset calculation unit and phase offset compensation unit as intermediary components between the FFT/IFFT processing and the output. These intermediary units specifically address the phase offset issue without disrupting the existing waveform distortion compensation mechanism, allowing both functions to coexist and maintain communication reliability.
3Reliability
If local oscillation light frequency control is implemented, then frequency deviation can be compensated, but device complexity increases due to additional control configuration
Solution Approach 1:
The patent replaces the mechanical/optical approach of controlling local oscillation light frequency with a digital signal processing approach. Instead of physically adjusting the local oscillation frequency, the system uses FFT-based frequency domain processing and digital phase offset compensation, which simplifies the device configuration while maintaining frequency deviation compensation capability.
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
Prevents errors caused by phase offsets during dynamic frequency deviation compensation, ensuring stable communication even when compensation amounts change.
Implementation Method 1
a frequency shift unit which shifts the signal in a frequency direction by a determined amount
Implementation Method 2
a phase offset compensation unit which compensates for a phase offset by inversely rotating a phase of data included in a process block
Data Source
AI summary
Because a phase offset occurs between adjoining input blocks of multiple divided blocks when the amount of frequency deviation compensation is dynamically changed, there is the possibility that a restored bit string contains an error. This frequency deviation compensation scheme is equipped with: a frequency deviation compensation means for compensating for a frequency deviation in a frequency-domain signal; and a phase offset compensation means for compensating for a phase offset caused to the signal due to change in an amount of compensation during the frequency compensation.