最新刊期
卷 ， 期 2 ， 2011
- 摘要：In this article,we adopt adaptive equalization technique to compensate Polarization Mode Dispersion（PMD）,and give the structure of decision feedback equalizer.Through improving part of the Feedforward Equalizer（FFE）,we obtain the Travelling-Wave Filter（TWF） and folded-cascaded TWF structure that is applicable to the high-speed rate fiber-optical communication systems.Finally,we obtain the S parameter simulation result with ADS simulation software.关键词：PMD;decision feedback equalizer;feedforward equalizer;travelling-wave filter
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发布时间： - 摘要：In multi-granular optical networks,in order to meet the requests for variable service bandwidths,lower the blocking rate for high-bandwidth service requests and reduce network resource waste in low-bandwidth service request access,we propose a layered virtual topology-based trans-granularity layer survivability enhancing method.With this method,we first design a layered virtual topology according to wavelength and waveband granularities and then calculate the working and protection paths on each granular or trans-granular layer according to service request bandwidths.Analytical results show that this method can effectively improve network resource utilization ratio and reduce blocking probability.关键词：layered virtual topology;trans-granularity layer;multi-granularity optical network;survivability
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发布时间： - 摘要：As large amount of computations are not only needed when the conventional Selected Mapping（SLM） technique is used for reducing OFDM system PAPR,but also the effective transmission efficiency is reduced because it is necessary to transmit the side information representing the phase sequence,we propose a linear block code-based coded-SLM algorithm both theoretical analysis and computer simulations show that although slightly poorer in reducing PAPR than the conventional SLM method,this algorithm can reduce the OFDM signal PAPR more effectively than the original OFDM technique and the transmission efficiency and reliability are also significantly improved.关键词：OFDM;PAPR;coded SLM;complementary cumulative distribution function
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发布时间： - 摘要：In optical communication systems,optical fibers have strong impacts on system properties.In order to minimize the effects of dispersion of multimode fibers on OOFDM system characteristics,a novel constant-throughput-based adaptive modulation algorithm is introduced.Compared with the original one,the improved algorithm is less complicated when the system BER remain not much changed.The simulation results indicate that the improved algorithm is corrects and feasible.关键词：adaptive modulation;power allocation;multimode fiber;OFDM
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发布时间： - 摘要：In EPON/GPON systems,ONU user ports loopbacks will cause the discontinuation of all the services at the same PON user ports.This paper first analyzes the common causes for the loopbacks and the serious consequences arising from them.Then,it lists five methods that can be used to prevent the ONU’s UNI ports from loopbacks and,on this basis,presents a "special message detection" method,which can be used to automatically discover and block the user port loopbacks by sending,receiving and comparing the special messages.关键词：GPON;EPON;UNI port loopback
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发布时间： - 摘要：Theoretical analysis of signal phase characteristics in Optical Orthogonal Frequency Division Multiplexing（O-OFDM） systems is presented in this paper.A new phase equalization method is proposed on the basis of the discussion on the influence of frequency-related nonrandom noises and the other random noises on signals.The formula between system Q and OSNR is also derived.Simulation verifies this phase characteristic and the feasibility of this phase equalization method.关键词：optical communication;O-OFDM;phase characteristic
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- 154
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发布时间： - 摘要：This paper introduces the WebSphere Application Server（WAS） platform and the Presence service architecture in IP Multimedia Subsystem（IMS） networks and explains the support of the WAS platform to the realization of the Presence server in IMS networks.Furthermore,it introduces the implementation of its main functions and presents a WAS platform-based design scheme and the treatment ideas in the implementation process.关键词：Websphere Application Server（WAS）;Session Initiation Protocol（SIP）;presence;publish;subscribe;notify
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发布时间： - 摘要：This paper introduces three methods that can be used to estimate the distribution of the link PMD coefficients by using cabled fiber PMD coefficients: Monte Carlo numeric method,Gamma distribution analytic method and model-independent analytic method,thus calculating the PMDQ value.It presents three method and the calculation processes and application conditions of the approximate solution by analyzing three lots samples,and analyzes the relationship between PMDQ value and the cabled fiber PMD coefficients.The results show that,the key factor for deciding PMDQ value is its statistic distribution of the cabled fiber coefficients rather than its average value.关键词：PMDQ;Monte Carlo numeric method;Gamma distribution;model independent;normal distribution
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- 86
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- 2
发布时间： - 摘要：The extinction ratio of a fiber-optic interferometer determines to a great extent the sensitivity of the interferometric fiber-optic sensing system.This article theoretically analyzes the factors affecting the extinction ratio of interference structure-based distributed fiber-optic vibration sensing systems and points out that polarization state is the main cause affecting the system extinction ratio.On this basis,a high cost-performance online polarization controller is designed and implemented.By tuning the polarization state,the dynamic equilibrium of the extinction ratio in long-distance distributed fiber-optic vibration sensing system is achieved.关键词：long distance;fiber-optic sensing system;polarization controller;extinction ratio
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- 126
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发布时间： - 摘要：This paper proposes a novel scheme for all-optical decoder based on cross-gain modulation in semiconductor optical amplifiers is proposed.It has its own advantages,such as high efficiency,wide wavelength range,logical operations only related to input optical power,so no need for precise phase control and being insensitive to polarization.It analyzes its work principle and simulates by OptiSystem.Finally,it also analyzed the relationship between the input pump power and the probe optical power and its output power and output extinction ratio.
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- 91
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发布时间： - 摘要：The resonant frequencies of the waveguide microcavity in the two-dimensional rectangular lattice photonic crystal are computed by using the Finite-Difference Time-Domain（FDTD） and Fast Fourier Transform（FFT） methods and the effects of the variations of the radius of dot defect dielectric rod and the refractive index of the background material on the resonant frequencies investigated.The results show that the resonant normalized frequency decreases with the increase of the radius or the refractive index.When the radius increases to 0.45r,normalized frequency of the resonant center is 0.336 and the transmission coefficient of the waveguide microcavity reaches a maximum of 98.02%.关键词：optoelectronics;photonic crystal;waveguide microcavity;FDTD;resonant frequency
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- 258
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发布时间： - 摘要：This paper designs a new type of plastic terahertz photonic crystal waveguide,using polyethylene（PE） that contains periodically lined triangular lattice air holes for its cladding and ne polytetrafluoroethene（PTFE） for its core.Its dispersion characteristics curves are simulated by the FDTD method.The study results show that this plastic waveguide is a photonic bandgap effect waveguide appropriate for terahertz wave transmission and has good transmission characteristics in terahertz waveband.关键词：terahertz wave;plastic photonic crystal waveguide;FDTD;waveguide dispersion
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- 141
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发布时间： - 摘要：A dual-core photonic crystal fiber temperature sensor is presented,achieving accurate temperature sensing by the resonance effects in the high refractive pillar between the two fiber cores.The air hole between the cores was injected with liquid crystal material.The temperature change of liquid crystal refractive index is used influence on the coupling characteristics between two cores,thus realizing accurate temperature sensing.Simulation results show that temperature sensing can be achieved by the measurement of light power transmitted through the dual-cores.Its sensitivity can be up to 2.5 mW/K.关键词：liquid crystal;coupling effects;dual-core photonic crystal fiber;temperature sensor
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发布时间： - 摘要：A physical heat dissipation model of coaxially packaged LD is built on the basis of the theoretical analysis of laser heat transfer process.Heat dissipation simulation analysis is made of two types of such LD,TO56 and TO38,by using the Computational Fluid Dynamics（CFD） software and a relevant experiment,i.e.a thermal resistance is installed in the LD,is designed to test the temperature of the laser-chip on submount.The experimental results are in a good agreement with the simulation,which has a certain guiding significance to the laser subassembly design.关键词：coaxial packaging;Semiconductor laser;heat dissipation;CFD
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发布时间： - 摘要：In view of time-varying and instability of crystal oscillators in phase lock loops due to the effects of temperature,a scheme of implicit self-tuning control combined with forward compensation is proposed on the basis of the recursive identification algorithm,i.e.implicit self-tuning control algorithm.This scheme designs the controller regulating system in accordance with the parameters obtained from the identification so as to minimize the output signal variance variations.Application of this algorithm in the self-tuning prediction modules and simulation and validation of this algorithm by using MATLAB show that application of this algorithm can not only optimize the system identification parameters,but also considerably stabilize the output signals,satisfying the requirement of the output signals in phase lock loops to track the input signals.关键词：phase lock loop;implicit self-tuning control;adaptive prediction module
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发布时间： - 摘要：A 1.25 Gbit/s integrated Trans-impedance Amplifier（TIA） circuit with controllable current monitoring for fiber-optic communications is proposed in this paper,which monitors the current flow of the current monitor by source current and sink current.Applied in the design is 0.18 μm standard CMOS technology.Simulation results show that when the optical current is within the range of 1 μA1mA,the detected errors is less than 5% in all technological conditions.关键词：TIA;fiber-optic communication;CMOS;source current;sink current
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发布时间： - 摘要：<正>OFC/NFOEC 2011美国光纤通信展开幕在即,武汉电信器件公司（WTD）于OFC展前夕发布了用于40 Gbit/s DWDM系统干线传输网线路侧的40 Gbit/s RZ-DQPSK Transponder模块等系列新产品,并将在2011 OFC展上进行部分新品的展示。
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发布时间： - 摘要：As the nodes in random waypoint mobility models move far away from the border areas with the lapse of time,resulting in their non-uniform steady-state distribution and difficulty in selecting the optimum μ value in uniform mobility models,this paper presents a mobility model,in which their moving distances in every moving period are subject to the uniform distribution relevant to the network diameter parameters.The experimental results show that the network packet delivery ratio has been increased and the network latency and routing overhead reduced.关键词：opportunistic network;node mobility model;NS2 network simulation
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发布时间： - 摘要：Comparing to 3G system,3GPP LTE has achieved both greater transmission rate and cell capacity,which means a much higher performance requirement on network Radio Resource Management（RRM）.In this paper,a key aspect of RRM,load balancing,is discussed.First,possible reasons leading to cell overload occurrence is analyzed,with investigation of potential risks result from traditional solutions in which cell handover is utilized.Then we have proposed a novel algorithm features in reduce searching scope of user equipment and avoidance of ping-pong effect.Simulation results show that this scheme could achieve optimized distribution of radio resources.关键词：Long Term Evolution（LTE）;Load Balance（LB）;Handover（HO）
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发布时间： - 摘要：On the basis of the study on the Digital Predistortion（DPD） algorithm,this paper presents a DPD algorithm that accomplishes the linearization of WCDMA RF power amplifiers in 3G radio communications by using QR decomposition.It can adaptively alter the filter coefficient to compensate the nonlinearity of the power amplifiers.Simulation results indicate that this algorithm is effective and useful.关键词：QR decomposition;RF power amplifier;digital predistortion;recursive least square;linearization
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发布时间： - 摘要：This paper introduces a high-precision positioning and navigation system,developed for the specific requirements of electric power line polling by using modern communication and geographic information technologies,which can make air pressure-based altitude measurements,supporting General Packet Radio Service（GPRS） wireless two-way communication,broken transfer resumption and custom-made maps.Then,it explains the system designing principle and modular functions and presents its advantages as compared with the traditional ones.Finally,it describes a practical example of this system.关键词：air-pressure-based altitude measuring technology;broken transfer resumption;GPRS;navigation and positioning;electric power line polling
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