Optical Transceiver Non-Linear Impairment Compensation
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Solution Overview
Problem
Existing optical communication networks face challenges in accurately transmitting and receiving high-data-rate signals due to non-linear, pattern-dependent impairments, which lead to poor bit error rates (BER) and increased infrastructure costs, as current compensation methods require additional hardware and can incorrectly compensate for intentional pre-distortion.
Innovation Solution
The implementation of a pattern-dependent analysis-based compensation system that generates a look-up table (LUT) at the receiver and applies it to the transmitter, allowing for multiple iterations of calibration and compensation to accurately adjust signals, reducing the need for additional hardware and minimizing incorrect compensation of intentional pre-distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional hardware is used for compensation, then signal accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces hardware-based compensation mechanisms with software-based digital signal processing. The digital signal processor implements impairment compensation algorithms that analyze received signals and generate correction data, substituting physical compensation hardware with computational methods. This reduces device complexity while maintaining signal accuracy through software-based equalization and compensation techniques.
Solution Approach 2:
The patent creates a digital model or copy of the channel impairment characteristics by analyzing received signals. The receiver generates compensation data that represents the inverse of the measured impairments, which is then transmitted back to the transmitter. This digital copy allows the transmitter to pre-compensate signals without requiring additional physical compensation hardware, reducing complexity while improving accuracy.
2Reliability
If conventional compensation methods are used, then some impairments are corrected, but incorrect compensation of intentional pre-distortion occurs
Solution Approach 1:
The patent segments the impairment compensation process into distinct phases: measurement of actual channel impairments at the receiver, separation of intentional pre-distortion from unintentional impairments, and selective compensation. The digital signal processor analyzes the received signal to identify which distortions are intentional (for pulse shaping, dispersion compensation) versus unintentional (amplifier non-linearity, crosstalk), and applies compensation only to the unintentional impairments, preserving the intentional pre-distortion.
Solution Approach 2:
The patent implements a feedback mechanism where the receiver measures the actual impairments affecting the transmitted signal and sends compensation data back to the transmitter. This closed-loop system allows the transmitter to adjust its output based on actual received signal quality, enabling selective compensation of impairments while preserving intentional pre-distortion through intelligent feedback control that distinguishes between harmful and beneficial signal modifications.
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AI summary
An optical transceiver comprises a transmitter configured to transmit a first signal, and a receiver coupled to the transmitter and configured to receive a first compensation, wherein the first compensation is based on a pattern-dependent analysis of the first signal, and provide the first compensation to the transmitter, wherein the transmitter is further configured to compensate a second signal based on the first compensation to form a first compensated signal, and transmit the first compensated signal. An optical transmitter comprises a digital signal processor (DSP) comprising a compensator, a digital-to-analog converter (DAC) coupled to the DSP, a radio frequency amplifier (RFA) coupled to the DAC, and an electrical-to-optical converter (EOC) coupled to the RFA. An optical receiver comprises an optical-to-electrical converter (OEC), an analog-to-digital converter (ADC) coupled to the OEC, and a digital signal processor (DSP) coupled to the ADC and comprising a calibrator.