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Low-complexity coherent DSCM system with precise transceiver IQ skew calibration and simplified equalization
Optics Letters
|November 27, 2024
Summary
This study introduces a low-complexity method to calibrate transceiver IQ skew in digital subcarrier multiplexing (DSCM) coherent systems. The new approach achieves performance comparable to complex MIMO equalizers with reduced computational load.
Area of Science:
- Optical Communications
- Digital Signal Processing
- Coherent Systems
Background:
- Digital subcarrier multiplexing (DSCM) is a promising technique for coherent optical systems.
- Transceiver IQ skew in DSCM systems causes conjugate interference in symmetric subcarriers (SC).
- Existing calibration methods, like MIMO, are computationally intensive.
Purpose of the Study:
- To develop a low-complexity transceiver IQ skew calibration method for coherent DSCM systems.
- To propose a simplified equalizer with embedded phase tracking (SEQPT) for reduced computational complexity.
- To validate the proposed methods experimentally.
Main Methods:
- A specially designed training signal is used for transceiver IQ skew calibration, avoiding MIMO operations.
- A simplified equalizer with embedded phase tracking (SEQPT) is proposed for polarization de-multiplexing, channel equalization, and phase noise compensation.
- Experimental validation in a 16-channel WDM system with 50 GBd 4SC-16QAM DSCM signals.
Main Results:
- The proposed skew calibration method achieves performance comparable to an 8x8 real-valued MIMO equalizer.
- The SEQPT offers polarization de-multiplexing, channel equalization, and phase noise compensation simultaneously.
- SEQPT incurs minimal performance penalty compared to conventional equalizers while maintaining low complexity.
Conclusions:
- The proposed low-complexity skew calibration method effectively mitigates IQ skew issues in DSCM coherent systems.
- SEQPT provides an efficient solution for equalization and phase noise compensation, reducing computational load.
- These advancements contribute to more practical and efficient coherent DSCM system designs.
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