最新刊期
卷 ， 期 4 ， 2017
- 摘要：In order to solve larger transmission delay jitter and poor robustness of ring network structure in intelligent substation communication system,the key technology of intelligent substation communication network is studied.The new communication network based on Ethernet Passive Optical Network（EPON）and connection-oriented switch uses measurable delay,business isolation and other technologies.The test results show that the new generation intelligent substation communication network architecture can satisfy the technical requirements of communication services,which is verified to be effective based on the proposed technical scheme.关键词：intelligent substation;EPON;measurable delay;business isolation
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发布时间： - 摘要：With the continuous evolution of network technology innovation,Software Defined Network（SDN）has become the technical trends for solving the existing network problems.The authors study the Floyd algorithm of the network under its centralized control feature with the open SDN technology.Meanwhile,the authors establish SDN simulation environments using Ryu and Mininet software,analyze and measure the link delay of the whole SDN,and propose Floyd algorithm for weight on link delay data as a method of optimal path.Finally,authors achieve the aims of reducing the network delay by the above environment design and experiments implementation.关键词：SDN;Ryu software;Mininet software;Floyd algorithm
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发布时间： - 摘要：Based on the studying on protection mechanism of optical communication,an auto,fast and reliable switching protection scheme is proposed for client card to increase the service survivability in certain optic OTN network equipment.The key points of the design are listed in the paper.This scheme is verified by scenario simulation and equipment test.The result shows that this scheme can improve the reliability for the network equipment.关键词：OTN access equipment;card protection;linear protection switching
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发布时间： - 摘要：A multi-service integration terminal scheme of DVB +IPTV/OTT + home gateway is designed to solve the problem of independent coexistence and interaction between multiple service terminals in the family.The integration of hardware design and software service function can effectively save the cost of production,and provide an integrated service experience for family users.The experimental results show that the proposed method can solve the current triple play in the multi-terminal integration of the family,which may have some reference value and practical significance.关键词：integration terminal;DVB;IPTV/OTT;home gateway
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发布时间： - 摘要：Due to the massive number and complicated connection of fiber connectors,the operation of the fiber operation can cause wrong connection,resulting in the interruption of communication services and even the grid event.In this paper,the research and development of construction guidance method based on intelligent software is discussed,which improve the accuracy of the optical fiber resources and the utilization rate of the core fiber through the development of the whole process control system with intelligent communication.The system can achieve the intelligent guidance through interface,text message and LED lights,which prompts the operators to correct the error according to the electronic work-order planning through the port of ODN.Therefore,the proposed method can avoid the misoperation caused by broken network port accident,improve the reliability of electric power communication network by port positioning via visual port guidance.关键词：smart optical distribution system;avoid the misoperation;power communication network
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发布时间： - 摘要：The distributed data communication equipment is mainly used to simulate the communication net in the real environment.It can not only emulate the transmission process of messages in single equipment,but also emulate the forwarding process of messages among the equipment.The system is based on the Linux operating system,C programming language and Socket programming language.It takes the core control module as the center,and sets up connections among the command shell,simulated devices,and TestCenters by the network protocol.Compared with the traditional simulation system,based on the support from control plane,the proposed system combines the forwarding plane to simulate the forwarding process.Therefore,the system can locate the problem of the data flow timely and solve it immediately.On the other hand,the system can also simulate the TestCenters.As a result,it reduces the cost of the engineering test,and improves the research efficiency.关键词：data communication;simulation system;distributed data communication equipment;device simulation
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发布时间： - 摘要：In terms of multipath interference induced by power line among Light Emitting Diodes（LED）,we introduce DFT-S OFDM with QR-CE to achieve successive interference cancellation.We first introduce a hybrid Power Line Communication（PLC）& Visible Light Communication（VLC）system based on Discrete Fourier Transform-Spread Orthogonal Frequency Division Multiplexing（DFT-S OFDM）,considering the multipath interference induced by electrical lines between two LED.Then we compare the BER performance of QR decomposition based Channel Equalizer（QR-CE）with that of Conventional Channel Equalizer（CCE）in this system.It is shown that DFT-S OFDM with QR-CE can achieve successive interference cancellation in hybrid PLC & VLC system with multipath interference among LED.The simulation result shows that the performance of QRCE is much better than that of CCE.关键词：free space optical communication;light emitting diode;power line communication;channel equalizer
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发布时间： - 摘要：In order to solve the mode crosstalk in the mode division multiplexing system,this paper proposes a kind of microstructured few-mode fiber with high Mode Differential Group Delay（MDGD）.The mode field distribution and the effective index are studied by using the Comsol software based on full-vector finite element method,and the MDGD is also analyzed.Simulation results show that the MDGD of LP11,LP21,LP02 versus LP01are 8.45,19.28,23.25ps/m,compared with the traditional few-mode fiber.It is also shown that the designed few-mode fiber has excellent high MDGD characteristics,which can solve the mode crosstalk problem efficiently,which may have important application in the mode division multiplexing system.关键词：mode division multiplexing;micro-structured fiber;finite element analysis;effective refractive index;mode differential group delay
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发布时间： - 摘要：In order to study the dynamic characteristics of submarine cable under wave force,a three-dimensional finite element model of submarine cable under wave force is established.Firstly,the cable model is established by using SOLID185 element and pipe59 element.Then the wave force and current velocity are set up.The model is simulated and the simulation result is extracted.The displacement,stress and strain of the submarine layer structure and optical unit acceleration data are obtained.Through the data processing,under the conditions of wave height of 0.1m,period of 1s,and sea speed of 2m/s,the vibration frequency of the optical unit is about 50 Hz,which provides a theoretical reference for monitoring the working state of submarine cable by distributed optical fiber vibration sensing technology.关键词：fiber-optic composite submarine cable;wave force;vibration frequency;dynamic analysis;finite element
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发布时间： - 摘要：In view of the nonlinearity problem in photonic crystal fiber,we design a new type structure of Photonic Quasi-crystal Fiber（PQF）.The designed PQF has a circular air hole,where the center hole hasa defect.The first three layer structure is used to realize inner claddingthrough the holes.The electromagnetic field analysis shows that narrower forbidden band of TM mode and wider forbidden band of TE mode can be achieved by increasing the angle of incidence.Moreover,the parametric analysis indicates that at the wavelength of 1 550 nm in optical communication systems,flat dispersion characteristic is observed.Finally,the loss can be controlled at small value by adjusting the distance between the holes and number of air hole level.关键词：optical fiber;nonlinear;photonic quasi-crystal fiber;flat dispersion
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发布时间： - 摘要：A nano-scale plasmonic system based on the Metal-Insulator-Metal（MIM）waveguide side coupled with two parallel rectangle resonator have been proposed and numerically simulated to realize the Plasmon-Induced Transparency（PIT）effect.The formation mechanism and evolution law of the transmission peaks based on PIT have been clarified by the theories of mode splitting and resonant coupling.By introducing the single resonator on the other side of the MIM waveguide,the double PIT peaks are observed in the transmission spectra.In addition,the locations of peak can be readily tuned by adjusting the resonator lengths.关键词：surface plasmons polaritons;metal-insulator-metal waveguide;finite element method;plasmonic-induced transparency
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发布时间： - 摘要：To improve the filtering performance of conventional Mach-Zehnder Interferometer（MZI）filter,a new structure of filter which combining ring resonator and MZI is proposed in this paper.The transfer function of this structure is first realized by using the Signal Flow Graph（SFG）method.Then the output spectra are simulated and analyzed.The results show that when the perimeter of ring resonator（L1、L2）and the length difference（Δd）of MZI arms meet the relationship of L1 =2L2 =Δd,the improved filter can give rectangular waves approximating flat top and steep edge.Through numerical calculation when choosing the perimeter of ring resonator is L1 =1 510μm,the free spectral can range up to 2nm,the full bandwidth at halfmaximum is 1.15 nm,the sharpness factor is 1.74 and the quality factor is 1 347.82.Therefore,compared with the conventional filter of MZI’s spectrum,the filtering performance is improved significantly.It is noted that by choosing the polymer materials with excellent photoelectric properties to design the ring resonator and MZI,the spectra are moving to the right side which can be adapted to the different filtering requirements when changing the voltage on the filter.关键词：ring resonator;Mach-Zehnder interferometer;signal flow graph;optical device;polymer materials
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发布时间： - 摘要：Single-ended Brillouin optical time domain analysis system can work in single-ended and measure the sensor information of the broken fiber,which is suitable for large-scale monitoring occasions.The Brillouin Optical Time-Domain Analysis system based on Rayleigh scattering（RBOTDA）realizessingle-ended sensing by impinging pulsed light and pulsed continuous light from the same end of the fiber.The Electro-Optic Modulator（EOM）is used to generate pulsed light and the pulsed substrate is the key technique of RBOTDA system.In order to get pulse light and continuous light in single frequency,two parallel EOM structure is proposed to generate the pulsed light for the RBOTDA system and the optimal operating point of the electrooptical modulator is discussed in this paper.It is proved that the design can produce the first-order double-side baseband continuous light and zero-order pulsed light.The proposed design overcomes the interference with single EOM,and reduces the requirements of EOM.关键词：single-ended;Rayleigh scattering;Brillouin optical time domain analysis;electro-optic modulator
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发布时间： - 摘要：Based on gain compensation of stimulated Brillouin scattering,we study the wavelength characteristics improvement of microwave photonic filter and propose an improved method in this paper.If the gain spectrum of stimulated Brillouin scattering is overlapped with two loss spectra,the wavelength selectivity and bandwidth tunability can be achieved.Through calculation,the bandwidth is reduced from 20 MHz to 3.8 MHz,which reduced by 81% and wavelength selectivity is increased by 5times.In some special fields,the bandwidth can be further reduced through the cascade of filters.In this way,the bandwidth can be reduced from 13 MHz to 2.5 MHz,which reduced by 80.8%,and wavelength selectivity is further improved.Through simulation and experiment,it is proved that the method is practical and feasible.关键词：microwave photonic filter;wavelength selection;bandwidth reduction;stimulated Brillouin scattering
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发布时间： - 摘要：In Ultra-High Voltage Direct Current（UHVDC）transmission system,optical fibers are used to replace the power lines to transfer the laser power to remote measurement modules.The laser power is then converted by photovoltaic cells to electric power to drive the sensors.Such an optic DC measurement system can realize isolation between high and low voltage circuit,insulation and anti-electromagnetic interference.Due to a high failure rate of the remote sensor,the operation principle,the structure and the weak point of the sensor are deeply analyzed.Based on the analysis,an improved DC measurement sensor is designed and developed.In the improved DC measurement sensor,the maximum power point tracking technique is adopted for the photovoltaic cell,and the circuit design of each module is optimized.These modifications not only improve the integration level of the modules but also the device performance.The on-site test results show that the measurement accuracy and power consumption of the improved sensor are better than those of the foreign sensor products.The designed sensor can improve the accuracy and stability of DC measurement systems.关键词：laser power over fiber;UHVDC;measuring sensor;maximum power point tracking technology
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发布时间： - 摘要：The reflection and transmission coefficients of the design structure is obtained based on sampled fiber Bragg grating,transfer matrix theory,a new type of photonic crystals with two different dielectric constants of materials arranged alternately periodic structure,and the theory of sampled fiber grating transmission.Simulation analysis and test results show that the design of photonic crystal structure appeared multiple reflection peak.The increase of grating length will increase the reflectivity and reflection peak number obviously without changing the reflection peak.The results also show that the bandwidth is increased obviously with larger modulation depth.With the increase of refraction index modulation,the peaks will also increase,and reflectivity is increased significantly（10%）.关键词：photonic crystal;sampled fiber grating;transfer matrix theory;reflection peak
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发布时间： - 摘要：Due to the high complexity of the Support Agnostic Bayesian Matching Pursuit（SABMP）algorithm in the support set search,a modified Bayesian sparse channel estimation algorithm is proposed in this paper.The modified Bayesian algorithm can improve the channel estimation accuracy by exploiting the sparse characteristics of the channel.The high-dimensional sparse channel is estimated by calculating the channel expectation.In order to improve the accuracy of the support set search,the idea of Viterbi path decoding is introduced in the search process of dominating support set.All the paths with probability difference below the threshold are preserved.Then,the channel estimation on the chosen support set is carried out and the channel expectation is calculated as the final channel estimate.Theoretical analysis and simulation results show that the lower computational complexity is maintained and the channel estimation accuracy is kept at the same time.关键词：Bayesian estimation;compressed sensing;Viterbi decoding;greedy algorithm;sparse reconstruction
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发布时间： - 摘要：In order to reduce the complexity of algorithm and improve the quality of channel transmission,a modified LDPC decoding algorithm is proposed in this paper.The algorithm is used in high speed mobile environment where multipath Rayleigh fading channel model is chosen considering the frequency selective deterministic scenario.At the same time,Taylor function approximation is adopted to reduce the amount of inspection node in cycling step,as well as the complexity of decoding.Simulation results show that,compared with BP LLR decoding algorithm,the modified LDPC decoding algorithm has better decoding performance,and can effectively reduce the decoding complexity.Therefore,the modified LDPC decoding algorithm can be applied in the high speed mobile environment,which can improve the quality and efficiency of channel transmission.关键词：LDPC code;LLR BP decoding algorithm;modified BP decoding algorithm;complexity
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发布时间： - 摘要：When there are multiple ZigBee wireless sensor networks in the same area,in order to solve the inter-network crosstalk problem such as mutual interference of the information transmission among sub-networks,the anomaly of coordinator network construction parameters and nodes disorderly joining in the network,we propose a ZigBee inter-network standard communication method.Using CC2530 as the hardware platform,the Z-Stack protocol stack is applied as the software platform to realize ZigBee technology.Through the research on the node type,network PANID,channel switching and network state storage in the Z-Stack protocol stack,and burning the matched Z-Stack protocol stack on different types of nodes,we can solve the inter-network crosstalk and inter-network communication problems.Several CC2530 nodes are used to compose multiple ZigBee subnets in practice test,which verifies the feasibility of the proposed scheme.关键词：ZigBee wireless sensor network;inter-network crosstalk;inter-network communication;Z-Stack protocol
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发布时间： - 摘要：In order to reduce the consumption of resources in the receiving signal of differential frequency hopping system,a new solution of differential frequency hopping is proposed.The system uses the encryption algorithm and the signal modulation method,which can effectively solve the resource and time consumption of the receiving signal in the differential frequency hopping system.It can also effectively improve the security performance of the system.The feasibility and practicability of the proposed scheme are proved by theoretical analysis and simulation verification.关键词：differential frequency hopping;encryption algorithm;modulation
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