Application of Kalman filter in frequency offset estimation for coherent optical quadrature phase-shift keying communication system

Jiang, Wen; Yang, Yanfu; Sun, Yunxu; Zhong, Kangping; Zhou, Xian; Yao, Yong

doi:10.1117/1.oe.55.9.096102

Cited by 13 publications

(8 citation statements)

References 11 publications

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“…The block length is 2 10 , and the total length is 2 15 . The power ratio between the QPSK and 16QAM is set as 6.5 dB, which can maximize the power efficiency [16]. The key parameter to be discussed in the following is the format ratio (FR).…”

Section: Simulation Resultsmentioning

confidence: 99%

“…The algorithms that were mentioned above such as CMA+BPS can be used for polarization tracking and carrier phase recovery. While we also have another choice, the extended Kalman filter (EKF) has been demonstrated in coherent optical transmission systems [15][16][17][18][19]. This is a joint scheme and can be used for polarization tracking and carrier phase recovery simultaneously, the overall computational complexity is lower than CMA+BPS.…”

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A Pilot Symbols Aided Adaptive Kalman Filter for Joint Carrier Phase and Polarization Tracking in Coherent Optical System

et al. 2018

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Featured Application: This work can good candidate for parameter estimation and channel equalization in elastic optical networks (EON).Abstract: A joint compensation scheme based on pilot symbols aiding adaptive Kalman filter (AKF) for phase noise and polarization cross-talk is proposed and investigated via numerical simulation and experimental demonstration. In the proposed scheme, the optimizing parameter Q is adaptively adjusted according to signal parameters or channel conditions. This improvement avoids the drawback of conventional extended Kalman filter (EKF), and its performance is strongly dependent on Q. Another improvement is that the convergence speed of AKF is improved. Pilot quadrature phase shift keyin (QPSK) symbols are inserted into 16 quadrature amplitude modulation (QAM) signals periodically. Besides accelerating convergence speed, the employment of pilot symbols also improves the tracking capability of AKF. The format ratio between pilot symbols and payload symbols is suggested under different system environments, for instance, optical signal-to-noise rate, polarization rotation frequency drift rate, and laser linewidth. With the proposed scheme, it has excellent tolerance to initial parameter Q and dramatically improves the performances in convergence speed, polarization rotation frequency drift rate tracking, and carrier phase recovery. Both the numerical simulation and experimental demonstration achieve convergence improvement for around 40 times than the original AKF. Additionally, the improvements in tracking ability are also demonstrated.Regarding polarization tracking, the traditional algorithms are the constant modulus algorithm (CMA) and its variants [11][12][13]. The CMA algorithm is capable of tracking polarization rotation of up to 1 Mrad/s [14], which is not enough for meeting the requirements imposed by dynamic or burst optical detection scenarios.For coherent optical communication system, both polarization tracking and carrier phase recovery are essential. The algorithms that were mentioned above such as CMA+BPS can be used for polarization tracking and carrier phase recovery. While we also have another choice, the extended Kalman filter (EKF) has been demonstrated in coherent optical transmission systems [15][16][17][18][19]. This is a joint scheme and can be used for polarization tracking and carrier phase recovery simultaneously, the overall computational complexity is lower than CMA+BPS. However, it is commonly known that the tuning parameters' Q value is significant for determining EKF performance. The higher laser linewidth, the larger Q value should be configured theoretically. The same rule exists in the case of tracking polarization rotation. Therefore, an adaptive Kalman filter (AKF) scheme is expected, in which Q value can change along with the conditions in an intelligent manner [20]. The convergence speed should be improved further in the case of high-order modulation format to meet the requirement of the next-generation dynamic optical transmission.Based on our prev...

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Section: Simulation Resultsmentioning

confidence: 99%

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confidence: 99%

A Pilot Symbols Aided Adaptive Kalman Filter for Joint Carrier Phase and Polarization Tracking in Coherent Optical System

et al. 2018

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“…The simulation results in [60] concludes that the Kalman filter can achieve faster convergence and outperforms the conventional FO estimation at low OSNR. In [64], FOE schemes based on blind and training data, using LKF and EKF have been proposed for QPSK systems. These Kalman based FOE algorithms are evaluated both numerically and experimentally, and are compared to FFT based FOE methods.…”

Section: Lkf and Ekf For Fo Estimationmentioning

confidence: 99%

“…These Kalman based FOE algorithms are evaluated both numerically and experimentally, and are compared to FFT based FOE methods. The investigations in [64] report that the training data based Kalman FOE methods show better accuracy in estimating the FO in case of fewer symbols and high OSNR, compared to FFT based methods. However, a separate phase estimation has to be carried out after FO compensation.…”

Section: Lkf and Ekf For Fo Estimationmentioning

confidence: 99%

“…This has attracted the Kalman filters for numerous real-time applications in the fields of navigation, radar, mobile communications, speech signal processing and so forth. Currently, EKF is under wide investigation in coherent optical communication systems for tracking and mitigating linear and nonlinear phase noise, amplitude noise, phase and frequency offsets as well as polarization de-multiplexing [12,13,31,[52][53][54][55][56][57][58][59][60][61][62][63][64][65][66].…”

Section: Introductionmentioning

confidence: 99%

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Applications of Kalman Filters for Coherent Optical Communication Systems

Pakala¹,

Schmauß²

2018

Kalman Filters - Theory for Advanced Applications

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In this chapter, we review various applications of Kalman filtering for coherent optical communication systems. First, we briefly discuss the principles of Kalman filter and its variations including extended Kalman filter (EKF) and adaptive Kalman filter (AKF). Later on, we illustrate the applicability of Kalman filters for joint tracking of several optical transmission impairments, simultaneously, by formulating the state space model (SSM) and detailing the principles. A detailed methodology is presented for the joint tracking of linear and nonlinear phase noise along with amplitude noise using EKF. Also, approaches to enhance the performance obtained by EKF by combining with other existing digital signal processing (DSP) techniques are presented. Frequency and phase offset estimation using a two stage linear Kalman filter (LKF)/EKF is also discussed. A cascaded structure of LKF and EKF by splitting the SSM to jointly mitigate the effects of polarization, phase and amplitude noise is also presented. The numerical analysis concludes that the Kalman filter based approaches outperform the conventional methods with better tracking capability and faster convergence besides offering more feasibility for real-time implementations.

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Joint polarization tracking and channel equalization based on radius-directed linear Kalman filter

Zhang

Zhong

Liu

et al. 2018

Optics Communications

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Application of Kalman filter in frequency offset estimation for coherent optical quadrature phase-shift keying communication system

Cited by 13 publications

References 11 publications

A Pilot Symbols Aided Adaptive Kalman Filter for Joint Carrier Phase and Polarization Tracking in Coherent Optical System

A Pilot Symbols Aided Adaptive Kalman Filter for Joint Carrier Phase and Polarization Tracking in Coherent Optical System

Applications of Kalman Filters for Coherent Optical Communication Systems

Joint polarization tracking and channel equalization based on radius-directed linear Kalman filter

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