最新刊期
卷 ， 期 3 ， 2022
- 摘要：In view of the problem that quadrature amplitude modulation has 1.53 dB capacity gap at the Shannon limit in high signal noise ratio, the paper proposes a joint shaping method of geometry and probability based on mutual information neural estimation. Geometric shaping and probability shaping are combined to improve the mutual information of the communication system. In this paper, the mutual information neural estimation is used to calculate the mutual information of the system, and the encoder of the transmitter is trained for the purpose of maximizing the mutual information, so as to realize geometric shaping and probability shaping. Through the simulation of Additive White Gaussian Noise (AWGN) channels with different signal noise ratios, it is proved that the performance of joint shaping of geometry and probability based on mutual information neural estimation is better than that of geometric shaping or probabilistic shaping separately. In AWGN channel with signal-to-noise ratio of 10 dB, the mutual information of the system has a gain of 0.041 7 bit/symbol over geometric shaping, and a gain of 0.027 9 bit/symbol compared over probability shaping.关键词：deep learning;mutual information neural estimation;physical layer communication
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发布时间：2022-06-15 - 摘要：Aiming at the current eavesdropping security issues in the physical layer of optical networks, a new hybrid optical encryption scheme based on Highly Nonlinear Fiber (HNLF) and Super Structured Fiber Bragg Grating (SSFBG) is proposed in this paper. In the scheme, degenerate Four Wave Mixing (FWM) is used to encrypt and decrypt user information, and optical coding technology is used to encode and decode the key information. Therefore, the encoding and secret transmission of the key signal can be realized simultaneously. The security of the system is measured by comparing the waveform of the encrypted signal transmitted in the channel with the waveform of the original transmitted signal, and the effectiveness of the system is measured by the bit error rate at the system receiver side. The simulation results show that the frequency and phase of the user data information are disturbed, and the optical power of the encoded key signal is as low as -34.4 dBm. Therefore, the eavesdropping channel cannot obtain effective data information nor detect the key signal, which demonstrates the safe transmission of Quadrature Phase Shift Keying (QPSK) signal.关键词：optical encryption;optical coding;hidden transmission;HNLF;SSFBG
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发布时间：2022-06-15 - 摘要：Millimeter wave large-scale Multiple Input Multiple Output (MIMO) system has more radio frequency links that bringing more power consumption, which could be efficiently tackled by using low-resolution Analog-to-Digital Converters (ADCs) in receiver. Considering the influence of the received signal amplitude distortion caused by low-resolution ADCs on the performance of channel estimation, a two-stage millimeter wave channel estimation algorithm is proposed after optimization. In the first stage, we construct the optimization problem which inequality constraints originating from the received signal determined by the quantized received signal and estimate the direction of arrival by using l1-norm to measure the sparsity. In the second stage, according to the estimated direction, Bussgang decomposition has been used to approximate the nonlinear quantization process, and the least square estimation of the complex channel gain is obtained. Simulation results show that the performance of the proposed algorithm is improved by about 5 dB compared with the current state-of-the-art algorithm, and the complexity is reduced to be linear. It can be seen that the proposed algorithm is greatly improved in terms of effectiveness and reliability, and has certain practical value.关键词：millimeter wave communication;massive MIMO;channel estimation;low-resolution ADC;convex optimization
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发布时间：2022-06-15 - 摘要：Wavelength Division Multiplexing (WDM) system has been evolving and upgrading in the direction of high speed, long distance and large capacity. In recent years, with the maturity of high-speed optoelectronic devices, the research and application of beyond 400 Gbit/s has made a rapid progress. Based on the technical status and requirements of 800 Gbit/s transmission systems, this paper discusses the key technical problems, sorts out the latest developments in standardization research. The evolution and application of 800 Gbit/s optical systems is further discussed.关键词：WDM;signal shaping;optical amplifier;standardization
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发布时间：2022-06-15 - 摘要：In this paper, we consider the Internet Protocol(IP) network quality and study the impact of network performance factors, such as delay and packet loss on the end-to-end service quality of major accounts and overall quality of internet. We propose a unified architecture design and conduct an investigation on IP network quality monitoring and optimization solutions through a combination of Telemetry, Twamp, IFIT, Flow and other applications of new technologies. The results indicate that the deployment of proposed design can provide effective improvements in the timeliness, authenticity and reliability of monitoring data. Meanwhile, it will collect and analyze the quality data of massive packet granularity, and realize fault warning with the help of AI intelligent prediction capabilities after the deployment of design. The proposed design can both improve the quality of services, and further enhance the existing network's " autonomous driving" capabilities.关键词：Key works: network quality monitoring;network quality optimization;solution design;intelligent warning
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发布时间：2022-06-15 - 摘要：Fiber Bragg Grating (FBG) has the advantages of anti-electromagnetic interference, corrosion resistance, small size and low cost. Moreover, the FBG fabricated by femtosecond laser has the unique advantages of high temperature resistance. Firstly, three mainstream methods for writing FBG with femtosecond laser are introduced, including femtosecond laser phase mask method, femtosecond laser direct writing method, and femtosecond laser holographic interferometry. The advantages and disadvantages are compared and analyzed. Secondly, the principle and application on temperature, pressure (strain) and refractive index sensing of FBG prepared by femtosecond laser are reviewed. Finally, the future development of FBG fabricated by femtosecond laser in lakes, oceans and other fields is prospected.关键词：femtosecond laser;FBG;sensing applications
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发布时间：2022-06-15 - 摘要：Optical fiber image transmission bundle is a passive device that using a certain number of regularly arranged optical fibers to transmit images. In order to ensure its imaging quality, the detection system for the number of optical fibers is optimized based on the machine vision technology. In view of the incomplete image acquisition of the end face of the optical fiber image transmission bundle or the defect of the edge, this paper proposes an edge optimization processing algorithm based on Euler number calculation, which can identify, mark and classify all the edge contours in the image. It not only realizes the accurate detection of the number of optical fibers, but also improves the performance of the algorithm through Graphic Processing Unit (GPU) processing. The algorithms in this paper are debugged and run in the environment of visual studio 2013, Opencv 3.1 and CUDA 10.1. The experimental results show that the detection error rate of the total number of optical fibers in the image is about 0.27%, and the error rate of optimized detection is about 0.03%, which basically meets the design requirements. Moreover, compared with the conventional detection methods, the optimization algorithm proposed in this paper can greatly reduce the selection requirements of threshold and have higher detection efficiency. With the support of Compute Unified Device Architecture (CUDA), the speed of bilateral filtering is increased by about 20 times, and the optimization algorithm and overall operation time are reduced by nearly 1/2.关键词：optical fiber image transmission bundle;optical systems;image processing;optimal detection;efficiency;Euler number
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发布时间：2022-06-15 - 摘要：The Microwave Photonic Filter (MPF) based on Stimulated Brillouin Scattering (SBS) effect not only has the advantages of low threshold and high gain, but also has the characteristics of reconfiguration and tuning. These characteristics make the filter attract extensive attention in the industry in recent years. By studying the MPF based on SBS, we obtain a filter with a large passband bandwidth and flat passband. Combining the Phase Modulator (PM) with the SBS effect, the bandwidth of the Brillouin gain spectrum can be changed by changing the number and frequency interval of the optical combs input by the pump branch. Therefore, the passband bandwidth and shape of the filter can be changed, and the reconfigurability of the filter bandwidth can be realized. By changing the shape of the pump branch, the flatness of the top of the Brillouin gain spectrum can be changed, as well as the flatness of the filter passband. The simulation results are obtained by Optisystem and Matlab. The characteristics of the MPF based on SBS effect with large passband and flat passband are investigated.关键词：MPF;filter;SBS;reconfigurable
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发布时间：2022-06-15 - 摘要：This paper presents a microfluidic multifunctional device, which can flexibly change the light input energy by using the effect of Electrowetting-on-Dielectric(EWOD). It can also realize multiple functions of variable aperture, variable optical attenuator and optical switch. The utility model has the advantages of simple structure, small volume, simple operation, wide application, flexibility and low cost. In this paper, the optical characteristics of the proposed microfluidic multifunctional device are analyzed and discussed, and the structure is optimized. The results show that the insertion loss of the proposed microfluidic multifunctional device is as small as only 0.014 dB. The aperture of the liquid variable aperture varies from 0 to 0.506 mm. In theory, the variable optical attenuator has a variable attenuation range of 0 ~100%, and the attenuation can reach 40.2 dB when the applied voltage is 91.1 V. The state microfluidic optical switch is " off" when there is no applied voltage and the state is " on" when the applied voltage is greater than 135 V.关键词：optofluidic;EWOD;variable aperture;variable optical attenuator;optical switch
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发布时间：2022-06-15 - 摘要：With the full deployment of 5th generation mobile communication network, the optical communication industry has entered the stage of comprehensive and rapid development. According to the demand of data center optical module market, the optical module will develop to high speed and low price in the future. The 400 Gbit/s Quad Small Form Factor Pluggable-Double Density (QSFP-DD) studied in this paper is based on the theory of near Gauss Beam. The optical path is designed and simulated by ZEMAX software, and the spherical parameters are optimized by the optimization function. The coupling efficiency is 74.8%, and the coupling efficiency under different offset is analyzed to get the error range. After analyzing the Fresnel reflection of the contact surface, and comparing the performance of the device under different grinding angles and the high-temperature fiber transmission test of the module, an oblique 8 ° for adaptation is selected. According to the requirements of the protocol, the optical design of this paper with 8 ° angle optical fiber can meet the requirements of the use of the scene.关键词：dater center;optical communication;400 Gbit/s optical module;simulation of light path;return loss
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发布时间：2022-06-15 - 摘要：The communication system between the islands has the problems of high cost and the transmitted signal may require relay amplification. In order to solve this issue, a novel Free Space Optical (FSO) communication system using Manchester encoded and decoded signals is designed. It can support 10 Gbit/s optical signal transmission over 100 km submarine cable (using G. 654 standard single-mode fiber) cascaded with 1 km FSO wireless link. We evaluate the performance by measuring the time-domain waveform, optical spectrum, eye diagrams and Bit Error Rate (BER) in simulation with Manchester coded signals, under sunny, rainy and foggy day. The measured results show that the receiver sensitivity can reach -18.92 dBm at the back-to-back system. Under the 100 km submarine cable and 1 km FSO wireless link, the receiver sensitivity can reach -17.72, -16.66 and -11.16 dBm in the sunny, rainy and foggy day, respectively. The simulation results prove that the FSO communication system using Manchester code may have potential application in the field of islands information transmission in the future.关键词：FSO communication;Manchester code;island;optical spectrum;BER
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发布时间：2022-06-15 - 摘要：Aiming at the problems of limited communication distance and low transmission rate of underwater radio frequency communication system, Visible Light Communication (VLC) system provides a solution for underwater medium and long distance high-speed wireless communication. In this paper, the underwater short-range channel model is estimated by using the sample water quality test. A test method of attenuation coefficient of short-range optical medium is proposed, and an underwater VLC system is developed. The direct-current bias circuit is designed according to the volt ampere characteristics of Light Emitting Diode (LED), and its spectrum response is analyzed. The underwater full duplex audio experiment with blue 465 nm and white light source is carried out in a water tank. The experimental results show that when the rated optical power is 1 W, the receiving end adopts S6968 silicon Positive Intrinsic Negative (PIN) photodetector, and the system can carry out full duplex communication in the sample water (denoted attenuation coefficient c=0.2067 m-1). The communication distance between the two light sources is more than 5m. The speech communication performance of the experimental system is verified through the analysis of the power spectrum estimation of the receiving signal, the signal-to-noise ratio test and the visual demonstration of the loudspeaker. The experimental results provide a guidance for the development of underwater VLC multi-service transmission system.关键词：VLC;underwater channel;voice communication;attenuation coefficient
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发布时间：2022-06-15 - 摘要：In this paper, time source sinking deployment scheme for the 5th Generation Mobile Communication Technology (5G) synchronization network is analyzed. Compared with the centralized deployment scheme, this paper analyzes the application scenario, advantages and deployment ideas of the source sinking deployment. The techniques of synchronization domain division, synchronization protection and control in the scheme are discussed, and corresponding solutions and suggestions are proposed. Finally, combined with the practice of domestic synchronization network, the evolution mode of time source sinking application is analyzed. The analysis results provide guidance for ongoing 5G synchronous networking technology research and scale deployment.关键词：synchronization network;time source;sink deployment;clock domain
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发布时间：2022-06-15
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