最新刊期
卷 ， 期 6 ， 2016
- 摘要：Aiming at the problem of high computational complexity of existing Blind Phase Search（BPS）algorithm,the thesis proposes a two stage carrier phase estimation algorithm based on improved QPSK partition algorithm.The first stage of the algorithm is based on traditional P3 algorithm,which is used to realize rough estimation.The second stage of the algorithm is based on the proposed improved QSPK partition algorithm,which is used to compensate the residual phase noise.The simulation results show that the performance of this algorithm is similar to that of BPS algorithm.However,the computational complexity is about 13 times lower than that of the BPS algorithm.关键词：coherent optical communication;carrier phase estimation;QPSK partition
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发布时间： - 摘要：To reduce the coherent Rayleigh noise,a Brillouin Optical Time Domain Reflectometer（BOTDR）system based on self-heterodyne detection of Rayleigh and Brillouin scattering employing multi-wavelength source is proposed.The mechanism of multi-wavelength probe light generation by phase modulation and the principle of self-heterodyne detectionfor three-wavelength system are analyzed.A self-heterodyne detection BOTDR system employing single-wavelength and three-wavelength probe lights are constructed,and the self-heterodyne detection signal power and Brillouin frequency shift along the sensing fiber are obtained.The experiment results show that the power fluctuation generated by the coherent Rayleigh noise can be reduced effectively.The increment of signal-to-noise ratio is approximately to be 4.56 dB by employing three-wavelength probe light,and the root-mean-square error of Brillouin frequency shift fluctuation is reduced by 2.2 MHz when compared with that in the single-wavelength system.关键词：fiber optics;multi-wavelength probe light;self-heterodyne detection;Brillouin frequency shift;power
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发布时间： - 摘要：In order to solve the issue of energy-saving protection in IP over WDM networks,a Hold-Time-Aware Green Shared Path Protection（HTAGSPP）algorithm is proposed.The algorithm also considers the issues of holding-time of traffic and use of renewable energy.It encourages choosing the path with the least additional traditional energy consumption during the holding-time of traffic.The simulation results show that our proposed algorithm can not only maintain a low blocking probability and use renewable energy effectively,but also reduce traditional energy consumption and carbon emissions by using more renewable energy,when comparing with other traditional energy-saving shared path protection algorithms.关键词：IP over WDM network;hold-time of traffic;renewable energy;shared path protection;low carbon emissions
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发布时间： - 摘要：The dynamic range of Rayleigh Brillouin Optical Time Domain Analysis（BOTDA）system is analyzed theoretically.A method using pulse coding is proposed to improve the signal-to-noise ratio and dynamic range of the system.The encoding and decoding principle of Simplex code and Golay code in Rayleigh BOTDA systemis introduced.Based on the analysis and comparison of signal-to-noise ratio improvement quantity using the method of superimposed averaging and pulse coding in Rayleigh BOTDA system,it is found that the pulse coding technology has more advantages in increasing dynamic range of the Rayleigh BOTDA system.The performance comparison is verified by using Matlab simulation.The simulation results show that the coding technology can significantly improve the signal-to-noise ratio as well as the dynamic range.关键词：Rayleigh BOTDA;dynamic range;pulse coding;superimposed averaging
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发布时间： - 摘要：The Software Defined Network（SDN）can provide simple and flexible network configuration and management.Recently,many proposals utilize the SDN controller as the Address Resolution Protocolproxy（ARP）,which obviously reduces the volume of broadcast flow in data plane and avoids the waste of bandwidth.However,since the recent controller has to use pro-active way to setup flow entries,it will cause the scalability problem when dealing with large amount of broadcast packets.Therefore,we propose a novel approach named Gater,which is a SDN-based distributed ARP proxy.Our approach uses the gateways as the ARP proxies,and they will respond to the ARP request in the corresponding LAN.According to the experimental results,our approach not only reduces the broadcast flow data in the network and the ARP response delay,but also lightens the payload of controller to achieve higher scalability.关键词：software defined network;broadcast;ARP proxy
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发布时间： - 摘要：The orbital angular momentum of vortex beams can be used to realize micromanipulation of the particles.It can also encode the particles to realize free space optical communication.Because of its wide potential applications,the characteristics of vortex beams have become a hot topic in recent years.In this paper,the propagation characteristic of integer order double-vortex beam is studied.The propagation expression of double-vortex beam is derived by using ABCD optical matrix firstly.Then under the condition of same topological charges,the evolution of double-vortex beam spotwith transmission distanceis observed by MATLAB software.The simulation results show that the spotcharacteristics of double-vortex beam can be preserved after propagation without affecting the orbital angular.It shows that the double-vortex beam is stable in the process of transmission,which is suitable for free-space optical communication system.关键词：double-vortex beam;propagation characteristic;light distribution;stability
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发布时间： - 摘要：A optical fiber communication system simultaneous transmitting millimeter-wave、Ultra Wide Band（UWB）signal and baseband signal is proposed.In central station,a 10 GHz radio frequency signal is used to drive two parallel Phase Modulator（PM）to produce third-order sideband.In base station,60 GHz millimeter wave is generated from the beating of optical detector.Electronic Gaussian pulses are utilized to drive dual Mach-Zehnder Modulator（MZM）to generate the second-order UWB signal.The UWB and baseband signals are modulated on the same optical carrier through polarization multiplexing.Simulation results show that the eye pattern is still clear after the 2.5Gbit/s signal transmitting over 20 km signal model fiber.The generated UWB signal meets the criterion of the U.S.Federal Communications Commission（FCC）,which has a central of 5.5GHz and a relative bandwidth of 98%.关键词：millimeter-wave;UWB;parallel PM;MZM;polarization multiplexing
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发布时间： - 摘要：With the construction of smart grid in recent years,as a service in the electric power industry,the power communication network has become important components in the system.Its reliability plays an important role in the normal production of electric power system.This paper presents a fuzzy analytic hierarchy process,which uses the fuzzy consistent matrix to quantitatively analyze the influence of each component on the reliability of power communication network.This approach greatly improves the scientific evaluation.By analyzing the calculation results,it is found that the failure time of power supply system,the rate of double channelization,the ring formation rate and the cable interruption time have great influences on the reliability of power communication networks.关键词：power communication network;reliability;fuzzy analytic hierarchy;quantitatively analyze
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发布时间： - 摘要：To generate all-optical domain monocycle UWB and doublet signals,and reduce the cost of UWB over-fiber system,a methodbased on polarization modulationisproposed.Two Gaussian pulses with opposite polarity arephase-modulated to theorthogonal optical carrierswith the Polarization Modulator（PM）.Then an appropriate group delayis introduced by Polarization Maintaining Fiber（PMF）to generate monocycle UWB signal.By changing the angle between the signal polarization direction and PMF principal axis,two monocycles UWB with opposite polarity can be generated.Then by introducing appropriate time delay to one of them before the combination of the two monocycles UWB,a doublet UWB can be obtained.Monocycle and doublet UWB have a central frequency about 5.36 GHz and 5.83 GHz,a-10 dB bandwidth about 8.96 GHz and 7.36 GHz,and a fractional bandwidth about 167 % and 126%,which both meet the FCC standards.The performance effects of the delay are analyzed.The result shows that whenτ= TFWHM,the generated doublet UWB signal meets the FCC standards best.关键词：monocycle and doublet UWB signals;polarization modulation;PMF
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发布时间： - 摘要：In this paper,a new type of double-mode photonic crystal fiber with flattened-dispersion is designed.The transmission and dispersion properties are simulated by Finite Element Method（FEM）.The impacts of the parameters of the PCF on the dispersion properties are analyzed.The results show that the double-mode PCF can gain stable transmission of the two modes when the structural parameters of PCF areΛ=10μm,d1/Λ=0.55,d2/Λ=0.65,d3/Λ=0.75.The confinement loss of each mode is less than 1dB/m,and the effective refractive index difference is larger than 10-3.The dispersion slope values ranges from-0.012 36ps/（nm2·km）to 0.321 91ps/（nm2·km）in the C band.The dispersion slope value in 1 550 nm of each mode are 0.093 80ps/（nm2·km）、0.038 97ps/（nm2·km）,which means that the PCF can achieve dispersion-flattened transmission in the wavelength range of communication.关键词：few-mode fiber;photonic crystal fiber;finite element method;dispersion
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发布时间： - 摘要：Life expectancy by an optical fiber screening test model shows that the main parameters affecting the life of the optical fiber are Weibull exponent m,stress corrosion susceptibility parameter nand the ratio of screening stress and static stress.This paper mainly focuses on the effects and determination of axial tension method and two-point bending method to the value of Nd,which is a key parameter to evaluate the fiber life.The values of Ndunder the two test methods for G.652 Dare statistically measured.The advantages and disadvantages of these two methods are also analyzed.Axial tension stretching method can find good fiber strength issue,but the implementation of optical fiber can be slippery.The bending method can well avoid fiber slippage problem,but it is difficult to find the strength of the optical fiber.Based on the above results,we suggest that both the test methods should be used in real application scenario.关键词：dynamic fatigue parameter;fiber life;axial tension method;two-point bending method
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发布时间： - 摘要：The angular absorber based on one-dimensional Photonic Crystal（PC）has been proposed and investigated.The absorber consists of multiple one dimensional PC,which has different periodicities.Both the real part and the imaginary part of the wave vector of the absorber will only have solutions at the Brewster angleby tailoring the overlap of the band gaps of these multiple one-dimensional PC.The absorber exhibits angular selectivity（the Brewster angle）in absorption within a broad waveband from 380 nm to 700nm（the visible wavelengths）under p-polarized illumination.It is also noted thatthe angular width in absorption is less than 5°.The simulation results show that the angular absorbance is above 99%,i.e.,perfect absorptionhas been achieved,when the incident lights illuminate on the absorber with the incident angle equalingto the Brewster angle.This feature of absorbing lights in a certain direction may have the potential in some new applications,such as solar thermophotovoltaic systems.关键词：photonic crystal;angular selectivity;the Brewster angle;absorber
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发布时间： - 摘要：To widen the frequency tunable range of the Optoelectronic Oscillator（OEO）,a frequency tunable OEO based on a chirped Phase-Shifted（PS）is simulated and designed by the Matlab software.Firstly,the characteristics of the reflective spectrum of a common PS-FBG and the frequency tunable range of the OEO based on the common PS-FBG are theoretically and studied via simulation.Then,a method of transfer matrix is employed to analyze the reflective spectrum of the chirped PS-FBG and the tunable range of the OEO based on the chirped PS-FBG.The simulation results show that the tunability of frequency is achieved by tuning the wavelength of a tunable laser source.Compared with the common PS-FBG,the bandwidth of the chirped PS-FBG is increased so that the frequency tunable range of the optoelectronic oscillator is widened.关键词：fiber Bragg grating;tunable;chirped phase-shifted;oscillator
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发布时间： - 摘要：In this paper,we use OptiGrating software to investigate the spectral characteristics of TFBG different modes when surrounding refractive index changes extremely little.Result shows that the micro change of refractive index has very little impact on core mode and phantom mode,but has great impact on the cladding modes.Because the change is very little,the drift of cladding mode resonant wavelength can be neglected,and only the variation of the resonant peak depth needs to be considered.The high-order cladding modes near 1 542 nm wavelength are sensitive to the surrounding refractive index.In a certain range of refractive index,the precision is extremely high with orders of magnitude up to 10-5.The simulation results obtained in this paper has broad prospects in high precision refractive index sensing field.关键词：TFBG;surrounding refractive index;higher-order cladding mode;high precision refractive index sensing
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发布时间： - 摘要：In order to improve the demodulating speed and precision of the instrument,this paper propose a double-edge demodulation and nonlinear correction method to modifythe hysteresis effectof the piezoelectric ceramic.The demodulating speed and accuracy of the instrument has been improved by a cross-demodulation method using the data at rising edge and failing edge of triangle voltage at the same time.The effectiveness of thenonlinear correction method has been verified using a C band grating with 10 detection points.It is found that the wavelength demodulation error is less than ±5pm.关键词：PZT;hysteresis effect;double-edge;nonlinear correction
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发布时间： - 摘要：<正>东湖之滨,光纤故里,烽火科技又一次迎来盛大时刻。在国家大力推动网络强国建设和纪念光纤通信技术诞生50周年之际,中国工程院与湖北省人民政府4日共同在武汉主办网络与信息高端论坛,18位中国科学院和中国工程院的院士围绕"下一代网络信息技术的发展趋势与挑战"进行了深入研讨。本次论坛由烽火科技集团承办,论坛议题包括:可覆盖海陆空的"天地一体化光网络"、微电子与集成电路、超级计算机系统、
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发布时间： - 摘要：<正>11月3日,2016CRU世界光纤光缆大会在武汉光谷隆重开幕。烽火通信作为此次大会金牌赞助商参会,与来自印度、英国、俄罗斯、圭亚那、印尼、荷兰、马来西亚、日本、意大利、德国、美国、奥地利、比利时等国600余名来自国际光纤光缆产业链及电信行业的参会代表共同出席,就光纤光缆全球化发展面对的机遇和挑战展开讨论。目前,武汉光谷已成为我国在光电子信息领域参与国际竞争的标志性品牌。在这里,中国第一根光纤在
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发布时间： - 摘要：Lack of flexibility in the deployment is one of the main issues of fiber broadband access.An application system is proposed to use RoF（Radio over Fiber）technology in broadband access.In fiber transmission,a lower frequency is selected to reducethe requirements for laser,and improve the utilization of fiber by combining SDM and WDM.According to the application,directional microwave antenna is selected to cover multi-user.In the system,maximum 48 users can be supported over one single fiber and the speed for each user can reach 35Mbit/s.Experimental results show that the system can effectively achieve the broadband access,which is more economic and easier to realize.关键词：ROF;broadband access;multiplex
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发布时间： - 摘要：In the spatial modulation system,a new differential spatial modulation scheme is proposed for four transmitting antennas based on differential coding.The scheme adopts the differential detection in the receiver.The differential detection is according to the difference of received signal in adjacent time,and only the initial channel parameters are required.The channel state information is not required at the transmitter and receiver sides.The change of channel parameters can be ignored in the process of communication.The simulation results show that the quaternary differential spatial modulation can not only realize communication,but also has good ability to resist the change of channel parameters.关键词：spatial modulation;differential coding;multiple-input-multiple-output;differential detection
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发布时间： - 摘要：This paper designs and realizes an indoor visible light localization system based on identification method.The system first loads the current position information to the LED light sources.Then the information will be transmitted to the mobile terminal through the wireless optical link,which calculate their relative positions in the environment according to the received information from the mobile terminal,and mapped to the map.Therefore,the system can achieve visible light positioning function,which meets the basic requirements of the lighting at the same time.We use the Stm32 processor as the main controller of the system,and design a kind of coding protocol,which can be used to transmit the position information in the visible light communication process.The characteristics and driving circuits of LED light sources are tested at the transmitter,which can guarantee the basic lighting and communication.The receiver uses C#language to compile the software of the host computer in order to realize the function of mapping and real-time updating of the mobile terminal’s position.The results show that the system can achieve ideal positioning performance.关键词：visible light communication;indoor positioning;identification method;position information;Stm32processor
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发布时间： - 摘要：Currently,LTE network below 6GHz spectrum is difficultto meet the growing demand for ultra-wideband.5Gcan provide a large number of continuous spectrum bands,which is the foundation of the future wireless network.For a variety of application scenarios,the factors that affect the spectrum occupation and the ways of occupation for high and low frequency bands are proposed.The results show that re-using lower band and new higher band could meet requirements of 5Gin future.关键词：5Gnetworks;spectrum band;above 6GHz bands;24GHz bands
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发布时间： - 摘要：In order to solve the problem of limited capacity in traditional MIMO system,the 3D MIMO system model is introduced in this paper.The multicell coordinated transmission technology is applied to the 3D MIMO system to improve the system capacity.According to the Shannon theory,we derive the expression of signal to interference plus noise ratio in single-cell transmission and multi-cell joint transmission,respectively.Then we adopt the Zero Forcing（ZF）precoding algorithm,and analyze theinfluences of the base station antenna down tilt,the distance between the user and the base station,the number of users for the system transmission rate.Simulation results show that appropriate adjustments to the base station antenna tilt can improve the transmission rate of the system.It is also verified the multicell coordinated transmission has better performance in increasing the throughput of the system,whencompared to the single-cell transmission.关键词：3D MIMO;transmission rate;coordinated transmission;ZF precoding
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