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Widely Linear Filtering for Multi-Impairment Compensation in Coherent Optical Systems
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  • Rekha Yadav ,
  • Lakshmi Narayanan Venkatasubramani ,
  • Ravinder David Koilpillai ,
  • Deepa Venkitesh
Rekha Yadav
Indian Institute of Technology Madras, Indian Institute of Technology Madras

Corresponding Author:[email protected]

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Lakshmi Narayanan Venkatasubramani
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Ravinder David Koilpillai
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Deepa Venkitesh
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Abstract

We propose a blind joint equalization algorithm for M-QAM signals based on a widely linear filtering approach. The proposed scheme jointly compensates receiver IQ imbalance and polarization mixing, along with carrier recovery, followed by transmitter IQ imbalance compensation. We first investigate the proposed scheme’s tolerance to transceiver IQ Imbalance, polarization mixing, phase noise and frequency offset through numerical simulations for 32 GBd PM-16QAM and PM-64QAM signals and compare its performance with the conventional digital processing algorithms. Further, with the proposed algorithm, we experimentally demonstrate the improvement in Q2 value to up to ~ 1.22 dB for a 32 GBd PM-16QAM and ~ 3.72 dB for a 16 GBd PM-64QAM signal with a phase imbalance of 9o. We show that the MSE convergence of the proposed joint equalizer is much faster than conventional DSP algorithms. Deployment of such an equalizer in optical communication systems is beneficial due to its improved tolerance to multiple impairments, albeit with increased complexity.
2022Published in IEEE Access volume 10 on pages 73278-73293. 10.1109/ACCESS.2022.3188633