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Channel estimation-based time-frequency neural network for post-equalization in underwater visible light communication

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chinese Optics Letters 2024年第6期22卷 116-122页

作者： Haoyu Zhang Li Yao Chaoxu Chen Yuan Wei Chao Shen Jianyang Shi Junwen Zhang Ziwei Li nan chi Key Laboratory for Information Science of Electromagnetic Waves(MoE) Department of Communication Science and EngineeringSchool of Information Science and TechnologyFudan UniversityShanghai 200433China Shanghai CIC of LEO Satellite Communication Technology Fudan UniversityShanghai 200433China Shanghai ERC of LEO Satellite Communication and Application Fudan UniversityShanghai 200433China

This Letter proposes a post-equalizer for underwater visible light communication(UVLC) systems that combines channel estimation and joint time-frequency analysis, named channel-estimation-based bandpass variable-order time-frequency network(CBV-TFNet). By utilizing a bandpass variable-order loss function with communication prior knowledge, CBVTFNet enhances communication performance and training stability. It enables lightweight implementation and faster convergence through a channel estimation-based mask. The superior performance of the proposed equalization method over Volterra and deep neural network(DNN)-based methods has been studied experimentally. Using bit-power loading discrete multitone (DMT) modulation, the proposed method achieves a transmission bitrate of 4.956 Gbps through a 1.2 m underwater channel utilizing only 38.15% of real multiplication calculations compared to the DNN equalizer and achieving a bitrate gain of440 Mbps and a significantly larger dynamic range over the LMS-Volterra equalizer. Results highlight CBV-TFNet's potential for future post-equalization in UVLC systems.

关键词： underwater visible light communication channel estimation post-equalizer neural network

High-speed GaN-based laser diode with modulation bandwidth exceeding 5 GHz for 20 Gbps visible light communication

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Photonics Research 2024年第6期12卷 1186-1193页

作者： JUNFEI WANG JUNHUI HU CHAOWEN GUAN YUQI HOU ZENGYI XU LEIHAO SUN YUE WANG YUNING ZHOU BOON S.OOI JIANYANG SHI ZIWEI LI JUNWEN ZHANG nan chi SHAOHUA YU CHAO SHEN School of Information Science and Technology Fudan UniversityShanghai 200433China Peng Cheng Laboratory Shenzhen 518000China ZGC Institute of Ubiquitous-X Innovation and Applications Beijing 100876China Photonics Laboratory King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia

Visible light communication(VLC)based on laser diodes demonstrates great potential for high data rate maritime,terrestrial,and aerial wireless data ***,we design and fabricate high-speed blue laser diodes(LDs)grown on c-plane gallium nitride(GaN)*** was achieved through active region design and miniaturization toward a narrow ridge waveguide,short cavity length,and single longitudinal mode Fabry–Perot laser *** fabricated mini-LD has a low threshold current of 31 mA and slope efficiency of 1.02 W/A.A record modulation bandwidth of 5.9 GHz(−3dB)was measured from the *** the developed mini-LD as a transmitter,the VLC link exhibits a high data transmission rate of 20.06 Gbps adopting the bit and power loading discrete multitone(DMT)modulation *** corresponding bit error rate is 0.003,satisfying the forward error correction *** demonstrated GaN-based mini-LD has significantly enhanced data transmission rates,paving the path for energy-efficient VLC systems and integrated photonics in the visible regime.

关键词： communication diode waveguide

基于离散采样模型的三自由度双旋翼直升机的控制器设计

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系统科学与数学 2024年第9期44卷 2588-2602页

作者：迟楠曾诚贵州理工学院理学院

三自由度纵列式双旋翼直升机模型是动力学系统研究中的一类重要实验对象,也是研究直升机飞行控制技术的平台.文章首先针对非线性三自由度纵列式直升机模型的系统描述,在其标准形描述和一般采样保持条件下,导出了比经典的Euler模型更精... 详细信息

三自由度纵列式双旋翼直升机模型是动力学系统研究中的一类重要实验对象,也是研究直升机飞行控制技术的平台.文章首先针对非线性三自由度纵列式直升机模型的系统描述,在其标准形描述和一般采样保持条件下,导出了比经典的Euler模型更精确的非线性近似离散时间模型,并进一步计算可得出,它们的近似离散模型的局部截断误差和全局截断误差分别为T5和T2,其中T为采样周期.其次,文章对非线性三自由度双旋翼直升机进行了系统辨识及其相应的简单讨论.最后,在导出的近似直升机离散采样模型的基础上,对非线性三自由度双旋翼直升机,文章给出了连续时间输入控制设计和李雅普诺夫再设计两种方法来开展对比研究,并通过实例表明李雅普诺夫再设计可增强系统的控制性能.

关键词：三自由度双旋翼直升机离散采样分析系统辨识采样控制器设计

Photonics-assisted THz wireless communication enabled by wide-bandwidth packaged backilluminated modified uni-traveling-carrier photodiode

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Opto-Electronic Science 2024年第7期3卷 20-29页

作者： Yuxin Tian Boyu Dong Yaxuan Li Bing Xiong Junwen Zhang Changzheng Sun Zhibiao Hao Jian Wang Lai Wang Yanjun Han Hongtao Li Lin Gan nan chi Yi Luo Beijing National Research Center for Information Science and Technology(BNRist) Department of Electronic EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Information Science of Electromagnetic Waves(MoE) Department of Communication Science and EngineeringFudan UniversityShanghai 200433China Flexible Intelligent Optoelectronic Device and Technology Center Institute of Flexible Electronics Technology of THUJiaxing 314000China

This paper presents a wide-bandwidth back-illuminated modified uni-traveling-carrier photodiode(MUTC-PD)packaged with standard WR-5 rectangular waveguide for high-speed wireless *** optimized epitaxy structure and coplanar waveguide electrodes,the fabricated 4-μm-diameter PD exhibits ultra-flat frequency response and high saturation *** passive circuits including low-loss bias-tee and E-plane probe are designed to package the PD into a compact module with waveguide *** packaged PD module has demonstrated a flat frequency response with fluctuations within±2.75 d B over a broadband of 140–220 GHz and a high saturated output power of-7.8 d Bm(166μW)at 140 *** wireless communication applications,the packaged PD is used to implement 1-m free space transmission at carrier frequencies of 150.5 and 210.5 GHz,with transmission rates of 75 and 90 Gbps,respectively.

关键词： modified uni-traveling-carrier photodiode integrated bias-tee E-plane probe flat frequency response high saturation power WR-5 output THz wireless communications

Lens-free wavefront shaping method for a diffuse non-lineof-sight link in visible light communication

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chinese Optics Letters 2024年第2期22卷 81-87页

作者：陈超旭周晓萌李子薇沈超张俊文施剑阳迟楠 Key Laboratory for Information Science of Electromagnetic Waves(MoE) Fudan UniversityShanghai 200433China Peng Cheng Laboratory Shenzhen 518038China

In this Letter,we propose and experimentally demonstrate a lens-free wavefront shaping method that utilizes synchronized signal block beam alignment and a genetic algorithm(SSBGA)for a diffuse non-line-of-sight(NLOS)visible light communication(VLC)*** proposed method effectively controls the position and mobility of visible light beams by partitioning spatial light modulator pixels and manipulating beams to converge at distinct spatial positions,thereby enhancing wavefront shaping efficiency,which achieves a significant 23.9 dB optical power enhancement at+2 mm offset,surpassing the lens-based continuous sequence(CS)scheme by 21.7 ***+40°angle,the improvement reaches up to 11.8 dB and 16.8 dB compared to the results with and without lens-based CS,respectively.A maximum rate of 5.16 Gbps is successfully achieved using bit-power loading discrete multi-tone(DMT)modulation and the proposed SSBGA in an NLOS VLC system,which outperforms the lens-based CS by 1.07 Gbps and obtains a power saving of 55.6%during the transmission at4 *** the best of our knowledge,this is the first time that high-speed communication has been realized in an NLOS VLC system without a lens.

关键词： non-line-of-sight lens-free wavefront shaping visible light communication

Flexible 2 × 2 multiple access visible light communication system based on an integrated parallel GaN/InGaN micro-photodetector array module

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Photonics Research 2024年第4期12卷 793-803页

作者： ZENGYI XU XIANHAO LIN ZHITENG LUO QIANYING LIN JIANLI ZHANG GUANGXU WANG XIAOLAN WANG FENGYI JIANG ZIWEI LI JIANYANG SHI JUNWEN ZHANG CHAO SHEN nan chi Key Laboratory for Information Science of Electromagnetic Waves(MoE) Department of Communication Science and EngineeringFudan UniversityShanghai 200433China National Institute of LED on Silicon Substrate Nanchang UniversityNanchang 330096China

In recent studies, visible light communication(VLC) has been predicted to be a prospective technique in the future 6G communication systems. To suit the trend of exponentially growing connectivity, researchers have intensively studied techniques that enable multiple access(MA) in VLC systems, such as the MIMO system based on LED devices to support potential applications in the Internet of Things(IoT) or edge computing in the nextgeneration access network. However, their transmission rate is limited due to the intrinsic bandwidth of ***, the majority of visible light laser communication (VLLC) research with beyond 10 Gb/s data rates concentrates on point-to-point links, or using discrete photodetector(PD) devices instead of an integrated array PD. In this paper, we demonstrated an integrated PD array device fabricated with a Si-substrated GaN/InGaN multiple-quantum-well(MQW) structure, which has a 4 × 4 array of 50 μm × 50 μm micro-PD units with a common cathode and anode. This single-integrated array successfully provides access for two different transmitters simultaneously in the experiment, implementing a 2 × 2 MIMO-VLLC link at 405 nm. The highest data rate achieved is 13.2 Gb/s, and the corresponding net data rate(NDR) achieved is 12.27 Gb/s after deducing the FEC overhead, using 2.2 GHz bandwidth and superposed PAM signals. Furthermore, we assess the Huffman-coded coding scheme, which brings a fine-grain adjustment in access capacity and enhances the overall data throughput when the user signal power varies drastically due to distance, weather, or other challenges in the channel condition. As far as we know, this is the first demonstration of multiple visible light laser source access based on a single integrated GaN/InGaN receiver module.

关键词： communication visible light

基于波前整形和自适应光学的水下可见光通信系统

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重庆邮电大学学报（自然科学版） 2024年第1期36卷 166-171页

作者：陈超旭徐迟施剑阳迟楠复旦大学电磁波信息科学教育部重点实验室上海200433

为了解决水下可见光通信中复杂的水下湍流、散射环境对光束造成的畸变而导致信号传输失败的问题,使用随机相位屏方法模拟了水下湍流信道,在发射端对光束进行波前整形实现远距离聚焦,接收端使用自适应相位恢复算法对接收端光斑进行恢复。... 详细信息

为了解决水下可见光通信中复杂的水下湍流、散射环境对光束造成的畸变而导致信号传输失败的问题,使用随机相位屏方法模拟了水下湍流信道,在发射端对光束进行波前整形实现远距离聚焦,接收端使用自适应相位恢复算法对接收端光斑进行恢复。在1.2 m水下实验平台使用比特功率加载技术发射离散多音信号(discrete multi-tone, DMT)信号测量接收光功率与数据传输速率的对应关系,基于此,预测了100 m湍流环境下可见光信号的传输速率,与经过波前整形以及自适应相位恢复后的结果对比得到,所提出的方法可以使得水下可见光系统的传输速率得到极大提升。

关键词：水下可见光通信波前整形随机相位屏湍流自适应光学

维普期刊数据库博看期刊

Demonstration of radar-aided flexible communication in a photonics-based W-band distributed integrated sensing and communication system for 6G

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chinese Optics Letters 2024年第4期22卷 119-124页

作者：贾俊连董博宇陶理施剑阳迟楠张俊文 Key Laboratory of EMW Information(MoE) Fudan UniversityShanghai 200433China Shanghai ERC of LEO Satellite Communication and Applications Shanghai CIC of LEO Satellite Communication TechnologyShanghai 200433China Science and Technology on Electromagnetic Compatibility Laboratory China Ship Development and Design CentreWuhan 430000China Peng Cheng Laboratory Shenzhen 518055China

This paper experimentally demonstrates a distributed photonics-based W-band integrated sensing and communication(ISAC) system, in which radar sensing can aid the communication links in alignment and data rate estimation. As a proof-of-concept, the ISAC system locates the users, guides the alignment, and sets a communication link with the estimated highest data rate. A peak net data rate of 68.6 Gbit/s and a target sensing with a less-than-1-cm error and a sub-2-cm resolution have been tested over a 10-km fiber and a 1.15-m free space transmission in the photonics-based W-band ISAC system. The achievable net data rates of the users at different locations estimated by sensing are experimentally verified.

关键词： integrated sensing and communication photonics-aided technique W-band radar-aided flexible communication

Support vector machine based machine learning method for GS 8QAM constellation classification in seamless integrated fiber and visible light communication system

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Science china(Information Sciences) 2020年第10期63卷 182-193页

作者： Wenqing NIU Yinaer HA nan chi Key Laboratory for Information Science of Electromagnetic Waves (MoE) Fudan University

Visible light communication(VLC) network over optical fiber has become a potential candidate in ultra-high speed indoor wireless communication. To mitigate signal distortion accumulated in optical fiber and VLC channel, we present to utilize support vector machine(SVM) for constellation classification in two kinds of geometrically-shaped 8 QAM(quadrature amplitude modulation) seamless integrated fiber and VLC system. We introduce 4 sub-bands to simulate multi-user. Experimental results show that system performance can be significantly improved, and transmission at-2.5 dB m input optical power under 7%forward error correction(FEC) threshold can be realized employing Circular(7, 1) geometrically-shaped8 QAM and SVM. At overall capacity of 960 Mbps, Q-factor increases by up to 11.5 dB.

关键词： visible light communication VLC support vector machine SVM geometrically shaping GS VLC network constellation classification