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Gerchberg-Saxton Based Pre-Electronic Dispersion Compensation in C-band IM/DD Transmissions over 100-km Dispersion-Uncompensated SSMF

Gerchberg-Saxton Based Pre-Electronic Dispersion Compensatio...

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Asia Communications and Photonics Conference (ACP) / International Conference on Information Photonics and Optical Communications (IPOC)

作者： Wu, Xiong Lu, Chao Karar, Abdullah S. Zhong, Kangping Lau, Alan Pak Tao Lu, Chao Lau, Alan Pak Tao Hong Kong Polytech Univ Photon Res Inst Dept EIE Hong Kong Peoples R China Amer Univ Coll Engn & Technol Kuwait Kuwait Poet Technol Inc Shenzhen Peoples R China Hong Kong Polytech Univ Shenzhen Res Inst Shenzhen Peoples R China

Using Gerchberg-Saxton-based iterative preelectronic dispersion compensation (EDC) and 30-tap post-FFE enables up to 75-GBaud and 100-GBaud OOK transmissions over 100-km dispersion-uncompensated SSMF, under 7% HD-FEC ... 详细信息

ISBN: (纸本)9781665481557

关键词： Gerchberg-Saxton algorithm electronic dispersion compensation intensity modulation and direct detection feed-forward equalizer small-signal analysis

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Filtered Asymmetrically Clipped Optical-OFDM With Index modulation for Optical Wireless Systems

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IEEE COMMUNICATIONS LETTERS 2021年第5期25卷 1592-1595页

作者： Azim, Ali Waqar Le Guennec, Yannis Chafii, Marwa Ros, Laurent CEA Leti MINATEC F-38054 Grenoble France Univ Grenoble Alpes GIPSA LAB Inst Engn CNRSGrenoble INP F-38000 Grenoble France CY Cergy Paris Univ ENSEA UMR 8051 ETISCNRS F-95000 Cergy France

In this letter, we present filtered asymmetrically clipped optical-orthogonal frequency-division multiplexing with index modulation (FACO-OFDM-IM) for optical wireless systems. FACO-OFDM-IM optimizes the baseband bandwidth by filtering out-of-band spectral leakage caused by clipping. Additionally, IM enables FACO-OFDM-IM to impart granularity for spectral efficiency (SE)/energy efficiency (EE) trade-off and to achieve higher SE over established counterparts. Hereby, we elucidate the transceiver architecture, SE/EE trade-off, and bit-error-rate (BER). Simulation results establish that FACO-OFDM-IM attains higher spectral efficiences than classical IM approaches and outperforms them for low alphabet cardinalities while marginally increasing the complexity.

关键词： Indexes OFDM Harmonic analysis Wireless communication Optical filters Bandwidth Transceivers Discrete Fourier transform orthogonal frequency-division multiplexing index modulation intensity modulation and direct detection optical wireless systems Internet-of-Things

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Adaptive bias layered optical OFDM based on precoding for IM/DD systems

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OPTICAL FIBER TECHNOLOGY 2023年第1期80卷

作者： Lu, Jia Jia, Nan Ma, Jie Liu, Jianfei Hu, Yaqi Wang, Yang Hebei Univ Technol Sch Elect & Informat Engn Tianjin 300401 Peoples R China Tianjin Key Lab Elect Mat & Devices Tianjin 300401 Peoples R China Hebei Prov Key Lab Adv Laser Technol & Equipment Tianjin 300401 Peoples R China

An adaptive bias layered optical orthogonal frequency division multiplexing (ABLO-OFDM) scheme based on real-valued precoding is proposed in the intensity modulation and direct detection (IM/DD) system. In ABLO-OFDM scheme, multilayer subcarriers are used to transmit data, which can achieve high spectral efficiency (SE) and reduce the peak average power ratio (PAPR). Compared with layered asymmetrically clipped O-OFDM (LACO-OFDM) scheme, only one inverse Fast Fourier transform (IFFT) block is needed in ABLO-OFDM. At the same time, the signal can be demodulated directly using the standard OFDM receiver. In addition, to resist the selective fading effect of the system, low-complexity real-valued precoding, namely discrete cosine transform (DCT) and discrete Hartley transform (DHT), are used to effectively balance the signal-to-noise ratio (SNR) between subcarriers and further reduce the PAPR. The result shows that the PAPR of the ABLO-OFDM system is reduced by 2.7 dB after adaptive bias layering, and the PAPR is further reduced by 2.4 dB at most after pre -coding. For the layered ABLO-OFDM system with DCT precoding, as the number of subcarrier layers decreases from L = 8 to L = 1, the required receiver optical power (ROP) is reduced by 6 dB. It proves that the ABLO-OFDM system with DCT precoding can achieve higher SE and effectively improve receiver sensitivity.

关键词： Orthogonal frequency division multiplexing intensity modulation and direct detection Adaptive bias Real-valued precoding

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Comparison of post-equalizers for beyond 100-Gb/s/A C-band signal transmission over a 100-km dispersion-uncompensated SSMF

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OPTICS COMMUNICATIONS 2023年第1期542卷

作者： Wu, Xiong Zhang, Junwei Lau, Alan Pak Tao Lu, Chao Hong Kong Polytech Univ Photon Res Inst Dept Elect & Informat Engn Hong Kong Special Adm China Hong Kong Peoples R China Hong Kong Polytech Univ Shenzhen Res Inst Shenzhen Peoples R China Photon Res Inst Dept Elect Engn Hong Kong Special Adm Reg China Hong Kong Peoples R China

A comprehensive comparison among different post-equalizers with relatively low complexity is studied for C -band 100-km dispersion-uncompensated standard single-mode fiber (SSMF) intensity modulation and direct detection (IM/DD) transmission systems with data rate beyond 100 Gb/s/A. These representative post -equalizers include feed-forward equalizer (FFE), polynomial-based nonlinear FFE (P-NFFE), absolute-term based nonlinear FFE (AT-NFFE), FFE combined with decision-feedback equalizer (FFE-DFE), polynomial based nonlinear FFE-DFE (P-NLE), absolute-term based nonlinear FFE-DFE (AT-NLE), and their lower-complexity versions of FFE-DFE-WS, P-NLE-WS, and AT-NLE-WS which use weight sharing (WS) to eliminate weight redundancy. We demonstrate 100-Gb/s/A and 112-Gb/s/A on-off keying (OOK) transmissions over a 100 -km SSMF. For 112-Gb/s transmission, BERs of FFE-DFE(-WS), P-NLE(-WS), and AT-NLE(-WS) can reach 7% hard-decision forward error correction (HD-FEC) limit at 3.8 x 10-3. Under 7% HD-FEC limit, AT-NLE-WS with 32 real-valued multiplications shows similar BER performance as P-NLE and AT-NLE with a small power penalty of < 0.4 dB, but outperforms P-NLE-WS, AT-NLE, and P-NLE in huge complexity reduction of approximately 83.2%, 92.4%, and 92.7%, respectively. Therefore, taking both the BER performance and the operation complexity into account, AT-NLE-WS is the optimal equalizer and is a strong candidate to be applied in low-cost C-band IM/DD interconnections with data rates beyond 100 Gb/s/A and transmission distance up to 100 km.

关键词： intensity modulation and direct detection (IM DD) Nonlinear equalizer (NLE) Absolute-term Weight sharing

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Single-wavelength 100-Gbps PAM-4 TDM-ZR-PON supporting 80-km downstream transmission with Over 31-dB power budget enabled by BDFA and SFO compensation

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OPTICS AND LASER TECHNOLOGY 2025年 189卷

作者： Long, Jianyu Wang, Chen Yu, Jianjun Sang, Bohan Yang, Xiongwei Chen, Yifan Zhang, Long Wu, Ying Wang, Ying Li, Yichen Wang, Kaihui Zhou, Wen Zhao, Li Wang, Tingyun Wen, Jianxiang Zhao, Feng Song, Yingxiong Wang, Yanyi Zhang, Jiao Zhu, Min Fudan Univ State Key Lab ASIC & Syst Key Lab Informat Sci Electromagnet Waves MoE Shanghai 200433 Peoples R China Fudan Univ Sch Informat Sci & Technol Shanghai 200433 Peoples R China Nanjing Univ Posts & Telecommun Sch Commun & Informat Engn Nanjing 210003 Jiangsu Peoples R China Shanghai Univ Key Lab Specialty Fiber Opt & Opt Access Networks Shanghai 200444 Peoples R China Xian Univ Posts & Telecommun Sch Elect Engn Xian 710121 Shaanxi Peoples R China Purple Mt Labs Nanjing 211111 Jiangsu Peoples R China

Single-wavelength intensity modulation/direct detection (IM/DD) passive optical networks (PONs) with less system costs and digital signal processing (DSP) complexity are still promising in the next generation of 100 Gbps PON systems, compared with the coherent scheme. In this paper, we propose to use a digital-interpolation-based sampling frequency offset (SFO) compensation method and bismuth-doped fiber amplifier (BDFA) in a single-wavelength 100-Gbps PAM-4 80-km-reach time-division multiplexing-(TDM-)ZR-PON downstream transmission system in the O-band, achieving a power budget of 31.1 dB by experimental demonstration. The BDFA with lower nonlinearity compared to semiconductor optical amplifier (SOA), ensures superior bit error rate (BER) performance for 50-GBaud 4-level pulse amplitude modulation (PAM-4) signals over 80-km standard single-mode-fiber (SSMF) transmission. Meanwhile, the proposed SFO compensation method maintains steady BER performance below the threshold, effectively addressing SFO up to 1000 ppm or payload durations up to 60 microseconds. In contrast, neglecting SFO or relying solely on the widely-used timing recovery Gardner method with near symbol interpolation proves insufficient for such scenarios. We also analyze SFO-induced inter-symbol interference (ISI) and demonstrate how it disrupts digital equalizers and universal clock recovery algorithms like Gardner's method.

关键词： Sampling frequency offset O-band Passive optical network intensity modulation and direct detection

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Improved SD-FEC with multi-tap error-tracking DFE with partial unrolling in high-speed IM/DD systems

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Chinese Optics Letters 2025年第1期23卷 25-30页

作者： Xue Zhao Jing Zhang Jiahao Zhou Chenye Wang Zhengyu Ma Shaohua Hu Bo Xu Kun Qiu Key Laboratory of Optical Fiber Sensing and Communications(Ministry of Education) School of Communication and Information EngineeringUniversity of Electronic Science and Technology of ChinaChengdu 611731China

We propose a multi-tap look-up-table(LUT)-based error-tracking decision feedback equalizer with partial unrolling(ET-DFEPU)algorithm to improve log-likelihood ratio(LLR)quality with error *** introduce an error-tracking model to obtain the probabilities of different error states,which are input into the decoder to obtain more accurate *** also use LUTs to reduce the computation complexity of ***,we adopt a low-complexity partially unrolled architecture to relax the feedback timing *** conduct experiments to transmit 170-Gb/s 4-ary pulse amplitude modulation signal in intensity modulation and direct-detection system at *** results show that the proposed method can achieve 3-d B receiver sensitivity improvement at the same post-forward error correction bit error ratio compared with the conventional DFE.

关键词： decision feedback equalizer error propagation tracking look-up table log-likelihood ratio intensity modulation and direct detection

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Geometric Constellation Shaping with Pulse Amplitude modulation in Short Reach Optical Links

Geometric Constellation Shaping with Pulse Amplitude Modulat...

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IEEE Microwave Theory and Techniques in Wireless Communications (MTTW)

作者： Singh, Jasmeet Sandmann, Andre Ahrens, Andreas Lochmann, Steffen Benavente Peces, Cesar Hsch Wismar Dept Elect Engn & Comp Sci Phillip Muller Str 14 D-23966 Wismar Germany Univ Politecn Madrid Escuela Tecn Super Ingenierfa & Sistemas Telecomu Carretera ValenciaKm 7 Madrid 28031 Spain

ISBN: (纸本)9781665424691

In optical communication, the higher-order modulation (HOM) schemes have attracted a lot of attention as they provide higher data rates within a defined bandwidth. Due to shot noise, the received data is affected by different noise variances depending upon the received power levels. In such systems, an equidistant constellation is not always optimal. Therefore, a geometric constellation shaping (GCS) approach is proposed. The purpose of this contribution is to investigate the potential of GCS with pulse amplitude modulation (PAM) to improve the bit-error rate (BER) performance. Moreover, this work aims to identify the conditions, e.g. the constellation size, where the GCS enhances the performance of an intensity modulated and direct detected (IM/DD) system. The GCS is realized with the aid of nonlinear optimization. In the analyzed scenarios, the simulation results show that GCS is not beneficial in terms of the BER performance for low constellation sizes. In contrast, GCS for high constellation sizes can significantly improve the BER. The experimental measurement results suggest that GCS can be advantageous.

关键词： Geometric Constellation Shaping intensity modulation and direct detection Higher-Order modulation Short Reach Optical Links

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Performance enhanced probabilistically shaped PAM4 signal based on nonlinear differential coding for IM/DD system

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OPTICAL FIBER TECHNOLOGY 2022年 71卷

作者： Liu, Tianyi Ma, Jie Lu, Jia Liu, Jianfei Zeng, Xiangye Wang, Yang Hebei Univ Technol Sch Elect & Informat Engn Tianjin 300401 Peoples R China Tianjin Key Lab Elect Mat & Devices Tianjin 300401 Peoples R China

In this paper, the probabilistically shaped pulse amplitude modulation (PS-PAM) signal is proposed in intensity modulation and direct detection (IM/DD) system. For the traditional shaping scheme with constant composition distribution matcher (CCDM), there are several problems that high-precision algorithm for long block coding, the loss of information rate for short block coding. In addition, it can increase nonlinear interference. In order to reduce computational complexity and alleviate the influence of nonlinear interference on the system, the nonlinear differential coding (NLDC) scheme is used to realize PS, which can be better integrated with the costeffective optical access network. This paper evaluates seven shaping spectrums obtained by different NLDC coding coefficients. As the coding coefficient increases, the performance of the system gradually improves. Moreover, this paper proposed the machine learning includes neural network (NN) and improved K-means clustering algorithm at the receiver. The results show that the PS-PAM4 signal is significantly better than the ordinary PAM4 signal in improving the channel bandwidth tolerance and signal transmission rate. Under the same data rate, using NLDC can save 5.8 GHz bandwidth for the system. For the bandwidth-limited system, the PS-PAM4 signal can obtain 19Gbit/s bit rate gain compared with the ordinary PAM4 signal. Compared with the typical shaping scheme using CCDM, this scheme can achieve 2.2 GHz band tolerance gain and 5Gbit/s rate gain in nonlinear fiber channel.

关键词： intensity modulation and direct detection Probabilistic shaping Nonlinear differential coding Neural network K-means clustering algorithm

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Theoretical and Experimental Analysis of Asymmetrically Clipped-FSK VLC System

IEEE PHOTONICS JOURNAL

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IEEE PHOTONICS JOURNAL 2022年第3期14卷

作者： Khan, Muhammad Jehangir Azim, Ali W. Le Guennec, Yannis Maury, Ghislaine Ros, Laurent Univ Grenoble Alpes Grenoble INP CNRS GIPSA LAB F-38000 Grenoble France Univ Engn & Technol Dept Telecommun Engn Taxila 39161 Pakistan Univ Grenoble Alpes Grenoble INP CNRS IMEP LAHC F-38000 Grenoble France

In this article, energy efficient asymmetrically clipped frequency-shift keying (AC-FSK) based visible light communication (VLC) system is theoretically and experimentally demonstrated. In order to facilitate straightforward comparison with the experimental results, theoretical expression for hit error probability, based on the Euclidean distance analysis of AC-FSK symbols, is provided. The VLC setup is based on commercial off-the-shelf components and software defined radio. The bit error rate (BER) performance of AC-FSK is evaluated considering maximum likelihood (ML) receiver, 1-tap discrete cosine transform (DCT) based receiver and frequency-domain harmonic receiver. Simulation and experimental results reveal that the performance of harmonic and ML receivers is almost identical. On the other hand, considering harmonic receiver for both AC-FSK and state-of-the-art unipolar (U)-FSK, we also gather that the BER performance of both schemes is almost the same. However, the harmonic receiver complexity of AC-FSK is 41.6% and 33.3% less compared to that of U-FSK for modulation order M = 16 and M = 128, respectively. This is because unlike U-FSK, AC-FSK requires limited number of harmonics for its optimal operation.

关键词： Frequency-shift keying visible light communication intensity modulation and direct detection energy efficient modulation

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Experimental demonstration of low complexity hybrid FFE algorithm for strictly band-limited IM/DD system

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OPTICS COMMUNICATIONS 2022年 505卷 127485-127485页

作者： Huo, Jiahao Sun, Mingwei Zhou, Xian Huangfu, Wei Yuan, Jinhui Ning, Huansheng Long, Keping Univ Sci & Technol Beijing Beijing Engn & Technol Res Ctr Convergence Networ Beijing 100083 Peoples R China

Feed forward equalizer (FFE) has been widely used in high-speed short-haul optical transmission. When system suffers from serious inter-symbol interference (ISI), i.e. low-cost transceiver induced narrow-bandwidth limitation, FFE with large number of taps is necessary, which significantly increases the computational complexity. In this paper, we proposed a hybrid FFE (H-FFE) algorithm with tap delay adjusted between T space and T/2 space. Enabled by the H-FFE and conventional T/2-spaced FFE algorithms, we demonstrated the intensity modulation and direct detection (IM/DD) transmission of 56, 70, and 80 Gbaud PAM4 signals over standard single mode fiber (SSMF) links up to 2, 1 km and 500 m employing the 18 GHz (3 dB) system bandwidth at C band. The experimental results indicate that the proposed H-FFE algorithm has the similar performance with the conventional T/2-spaced FFE algorithm. In addition, using the proposed H-FFE algorithm, the computational complexity is one third of that of the conventional T/2-spaced FFE algorithm.

关键词： intensity modulation and direct detection Inter-symbol interference Feed forward equalizer

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