Reduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system

Abstract We propose 1 state and 2 state multi-step Kalman filters (MKFs) to estimate and compensate CFO, LPN and NLPN in long-haul coherent fiber-optic communication systems. The proposed filters generate state estimates once every m symbols and therefore operate at a reduced sampling rate compared...

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Autores principales:	Srishti Sharma, Pradeep Kumar Krishnamurthy
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/603943c283b349219ab3b465ff45a92c
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spelling	oai:doaj.org-article:603943c283b349219ab3b465ff45a92c2021-12-02T13:51:15ZReduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system10.1038/s41598-020-80822-z2045-2322https://doaj.org/article/603943c283b349219ab3b465ff45a92c2021-01-01T00:00:00Zhttps://doi.org/10.1038/s41598-020-80822-zhttps://doaj.org/toc/2045-2322Abstract We propose 1 state and 2 state multi-step Kalman filters (MKFs) to estimate and compensate CFO, LPN and NLPN in long-haul coherent fiber-optic communication systems. The proposed filters generate state estimates once every m symbols and therefore operate at a reduced sampling rate compared to conventional KFs that perform symbol by symbol processing. No computations are performed to obtain phase estimates of the intermediate $$m-1$$ m - 1 samples; instead, the present and previous estimates are averaged and used to derotate the intermediate $$m-1$$ m - 1 samples which are then demodulated to recover the transmitted symbols. This reduces the computational load on the receiver DSP. Further, in order to improve estimation accuracy, we adaptively vary the process noise covariance Q. Simulation results of 200 Gbps PDM 16 QAM system over 12 spans shows that the proposed 1 state MKF can reduce the sampling rate requirement by a factor of $$m = 20$$ m = 20 with Q-factor degradation of 1.32 dB compared to single-step KF at linewidth of 100 kHz. The 2 state MKF tracks PN and CFO with a maximum step size of $$m=10$$ m = 10 for a CFO of 100 MHz at linewidth of 100 kHz. We also study the dynamic performance of the proposed algorithms by applying step change to CFO. The 2 state MKF with adaptive Q is able to track a step change of 400 MHz of CFO with $$m = 1$$ m = 1 and 3 with high estimation accuracy but slower convergence time compared to the non-adaptive 2 state MKF. Finally, we study the computational requirements of the proposed MKFs and show that they offer significant reduction in computations compared to single-step KF thus making the proposed filters suitable for hardware implementation.Srishti SharmaPradeep Kumar KrishnamurthyNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Srishti Sharma Pradeep Kumar Krishnamurthy Reduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system
description	Abstract We propose 1 state and 2 state multi-step Kalman filters (MKFs) to estimate and compensate CFO, LPN and NLPN in long-haul coherent fiber-optic communication systems. The proposed filters generate state estimates once every m symbols and therefore operate at a reduced sampling rate compared to conventional KFs that perform symbol by symbol processing. No computations are performed to obtain phase estimates of the intermediate $$m-1$$ m - 1 samples; instead, the present and previous estimates are averaged and used to derotate the intermediate $$m-1$$ m - 1 samples which are then demodulated to recover the transmitted symbols. This reduces the computational load on the receiver DSP. Further, in order to improve estimation accuracy, we adaptively vary the process noise covariance Q. Simulation results of 200 Gbps PDM 16 QAM system over 12 spans shows that the proposed 1 state MKF can reduce the sampling rate requirement by a factor of $$m = 20$$ m = 20 with Q-factor degradation of 1.32 dB compared to single-step KF at linewidth of 100 kHz. The 2 state MKF tracks PN and CFO with a maximum step size of $$m=10$$ m = 10 for a CFO of 100 MHz at linewidth of 100 kHz. We also study the dynamic performance of the proposed algorithms by applying step change to CFO. The 2 state MKF with adaptive Q is able to track a step change of 400 MHz of CFO with $$m = 1$$ m = 1 and 3 with high estimation accuracy but slower convergence time compared to the non-adaptive 2 state MKF. Finally, we study the computational requirements of the proposed MKFs and show that they offer significant reduction in computations compared to single-step KF thus making the proposed filters suitable for hardware implementation.
format	article
author	Srishti Sharma Pradeep Kumar Krishnamurthy
author_facet	Srishti Sharma Pradeep Kumar Krishnamurthy
author_sort	Srishti Sharma
title	Reduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system
title_short	Reduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system
title_full	Reduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system
title_fullStr	Reduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system
title_full_unstemmed	Reduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system
title_sort	reduced sampling rate kalman filters for carrier phase and frequency offset tracking in 200 gbps 16 qam coherent communication system
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/603943c283b349219ab3b465ff45a92c
work_keys_str_mv	AT srishtisharma reducedsamplingratekalmanfiltersforcarrierphaseandfrequencyoffsettrackingin200gbps16qamcoherentcommunicationsystem AT pradeepkumarkrishnamurthy reducedsamplingratekalmanfiltersforcarrierphaseandfrequencyoffsettrackingin200gbps16qamcoherentcommunicationsystem
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Reduced sampling rate Kalman filters for carrier phase and frequency offset tracking in 200 Gbps 16 QAM coherent communication system

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