Yi, W;
Sillekens, E;
Lavery, D;
Dzieciol, H;
Zhou, S;
Law, K;
Chen, J;
... Killey, RI; + view all
(2020)
Performance of momentum-based frequency-domain MIMO equalizer in the presence of feedback delay.
Optics Express
, 28
(13)
pp. 19133-19143.
10.1364/oe.394304.
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Abstract
A frequency-domain multiple-input multiple-output (FD-MIMO) equalizer employing a momentum-based gradient descent update algorithm is proposed for polarization multiplexing coherent receivers. Its performance in operation with dynamically varying optical channels is investigated and the impact of filter update delays, arising from the latency of the fast Fourier transforms (FFTs) and other digital signal processing (DSP) operations in the feedback loop, is assessed. We show that the proposed momentum-based gradient descent algorithm used to control the equalizer response has significantly greater tolerance to feedback delay than the conventional gradient descent algorithm. We considered a 92 Gbaud dual-polarization 64 QAM receiver, with DSP operating at two samples per symbol, and with the equalizer operating on blocks of 512 and 1024 samples (i.e., 512/1024-point FFT). We found that at an optical signal-to-noise power ratio (OSNR) of 35 dB, the momentum-based gradient descent algorithm can successfully track state-of-polarization (SOP) rotation at frequencies of up to 50 kHz and with filter update delays of up to 14 blocks (39 ns). In comparison, using the conventional gradient descent algorithm in an otherwise identical receiver, the equalizer performance starts to deteriorate at SOP rotation frequencies above 20 kHz.
| Type: | Article |
|---|---|
| Title: | Performance of momentum-based frequency-domain MIMO equalizer in the presence of feedback delay |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1364/oe.394304 |
| Publisher version: | https://doi.org/10.1364/oe.394304 |
| Language: | English |
| Additional information: | Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10101651 |
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