Phase Offset Tracking for Free Space Digital Coherent Optical Communication System

Li, Hongwei; Huang, Yongmei; Wang, Qiang; He, Dong; Peng, Zhenming; Li, Qing

doi:10.3390/app9050836

Cited by 4 publications

(3 citation statements)

References 20 publications

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“…The authors have evaluated the performance of the system by deriving novel mathematical expressions for the outage probability and the average bit error rate performance. Li et al have considered coherent FSO systems [3] and propose a new method for the measurement and estimation of the phase offset introduced by the atmospheric channel. The method combines the existing Viterbi-Viterbi phase offset estimation method with Kalman filter, which leads to lowering the estimation error by no less than 60%, even when the signal to noise ratio (SNR) is low.…”

Section: Outdoor Systemsmentioning

confidence: 99%

Special Issue on Light Communications: Latest Advances and Prospects

et al. 2022

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Section: Outdoor Systemsmentioning

confidence: 99%

Special Issue on Light Communications: Latest Advances and Prospects

et al. 2022

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“…The scintillation in atmospheric channel will bring amplitude noise, and the smaller the amplitude is, the easier it is close to the decision threshold under phase noise, which will increase the probability of error. A combination of Viterbi-Viterbi phase estimation and linear kalman filter (LKF) was presented to improve estimating accuracy in low signal-to-noise case [16]. However, this combination algorithm used linear approximation could discard the nonlinear components and did not take the amplitude noise into account.…”

Section: Introductionmentioning

confidence: 99%

Flexible Phase Synchronization for Wireless Optical Coherent Communication System With Adaptive Fractionally-Spaced Blind Equalization Combined With Adaptive Kalman Filter

Zhang,

Tan,

2023

IEEE Photonics J.

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Wireless optical coherent communication can be used as the backbone supporting technology of air-space-spacesea-integrated network. In wireless optical coherent communication, the information can be demodulated from the carrier correctly only when the phase synchronization is accurate. Operating in different systems and diverse environments presents challenges for phase synchronization, especially lasers with different line-widths and atmospheric turbulence channels that cause scintillation and wave-front distortion. We propose a combination of adaptive fractionally-spaced blind equalization and adaptive kalman filter to realize phase synchronization under different line-widths and different scintillation and wave-front distortion. This combination which changed the limitation that the original settings of each part is not directly applicable to atmospheric channel combines spatial diversity in a natural way, jointly removes amplitude noise and phase noise more thoroughly with the optimal bandwidth, and can realize phase synchronization under time-varying conditions. The signal quality of the proposed scheme with constant parameter output can be improved 1-2dB in both mean square error (MSE) and symbol to error ratio (SER) compared to traditional equal gain combining (EGC) followed by Viterbi-Viterbi phase estimation (VVPE) and the proposed constant parameter scheme has more laser linewidth options. The proposed scheme with noise parameter corrected by Autoregressive method outperforms the constant parameter scheme 1-2dB at both MSE and SER and has higher and wider line-width selections. With this design, phase synchronization can be more flexible to adapt to dynamic changes, which will be more suitable for future applications of wireless optical networks with dynamic ,noisy, diverse environment.

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“…Compared to the conventional AFTs, auto-focusing methods based on digital image processing (DIP-AF) have been found to have the advantages of integrated, miniaturized, and low-cost applications [13], such as digital camera, video camera, and microscope imaging [14,15]. However, little attention has been paid to AFTs with telescope systems, which are critical for capturing large amounts of image information through high-resolution CCDs in applications of astronomy observations [16,17]. To investigate the focusing performance of the telescope system, in this paper, we analyzed the effect of the image estimation function and focusing window selection, and we propose a novel adaptive dynamic focusing window selection method with high sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Accurate and Rapid Auto-Focus Methods Based on Image Quality Assessment for Telescope Observation

Yang

Chen

Zhou³

et al. 2020

Applied Sciences

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Aiming at improving the speed and accuracy of auto-focus for telescope observation, algorithms for image estimation and auto-focus were investigated and are discussed in this article. Based on the image quality assessment, the auto-focusing process of the telescope system is realized by using the mountain-climb search method. Several evaluation functions were tested in different scenarios. It is demonstrated that the Tenengrad image estimation function (IEF) is suitable for an instant and accurate auto-focus process of the telescope. Furthermore, we implemented sampling and dynamic adaptive focusing window (ES-DAFW) methods with the Tenengrad IEF to enhance the sensitivity and accuracy of the auto-focus process. The experimental results showed that our ES-DATW method can provide more accurate results in less time for the auto-focus process compared to the conventional approaches, especially for a sparse image. These results promise significant applications to the auto-focusing of other telescopes with image quality assessment.

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Phase Offset Tracking for Free Space Digital Coherent Optical Communication System

Cited by 4 publications

References 20 publications

Special Issue on Light Communications: Latest Advances and Prospects

Special Issue on Light Communications: Latest Advances and Prospects

Flexible Phase Synchronization for Wireless Optical Coherent Communication System With Adaptive Fractionally-Spaced Blind Equalization Combined With Adaptive Kalman Filter

Accurate and Rapid Auto-Focus Methods Based on Image Quality Assessment for Telescope Observation

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