最新刊期
卷 ， 期 6 ， 2007
- 摘要：Generalized Multi-Protocol Label Switching（GMPLS） is used as the control protocol for ASON,of which the routing part is mainly governed by the Open Shortest Path First（OSPF） protocol.In this paper,the hidden trouble in the encryption for OSPF protocol is analyzed and the existing encryption schemes improved.A new and safer scheme applicable to the routing technology in ASON is proposed.On the basis of the number-theoretic algorithm,the S-box is dynamically adjusted to prevent differential cryptanalysis.The encryption solution fulfills the confusion and diffusion principle.关键词：OSPF;Data Encryption Standard（DES）;primitive root;block cipher;multiplicative group
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发布时间： - 摘要：All-optical wavelength conversion by using idle light is simulated with OptiSystem software.By adjusting the injection current and cavity length of SOA,the frequency difference between pump light and signal wavelength,polarization,signal attenuation of the coupler and pump attenuation,the wavelength conversion efficiency of about 12 dB is achieved.It is found out in the study that all-optical wavelength conversion by using the idle light has better stability than by using the transformed light.关键词：all-optical wavelength conversion;FWM;OptiSystem;SOA
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- 172
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发布时间： - 摘要：Optical networks are more complicated than the traditional graph-theoretic networks with nodes and links,but their reliability can be effectively improved by the use of disjoint paths.In this paper,we propose an improved ant-algorithm-based disjoint routing algorithm.Compared with the shortest path first algorithm,we find that this algorithm behaves much better in diverse path searches.关键词：disjoint route;ant algorithm;shortest path first algorithm
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发布时间： - 摘要：Optical Burst Switching（OBS） is regarded as one of the representative technologies for the next generation fiber-optic communication networks.In this paper,the contention issue arising from data bursts contending for the same output data channel in the OBS core node is studied,the network performances in the contention analyzed and the packet loss probabilities under different network traffics obtained.The results of the study have certain theoretical guiding significance to the construction of OBS networks.关键词：OBS;data burst;contention;packet loss probability
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发布时间： - 摘要：As a novel optical switching technology proposed in recent years,Optical Burst Switching（OBS） combines the advantages of Optical Circuit Switching（OCS） and Optical Packet Switching（OPS）,but it is more flexible than OCS and provides more easily realizable statistical multiplexing capabilities at the optical layer than OPS.In addition,OBS provides high throughput,high-bandwidth availability and low transfer delay,making it a forceful competitor for the next-generation MAN.Using the M/G/1 queuing model,we develop an analytical approximation for the transfer delays of different priority burst packages under a constrained condition and derivate the transfer delays of the burst packages in OBS ring networks.关键词：OBS;ring network;queuing theory;transfer delay
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- 64
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发布时间： - 摘要：A new bursty assigned traffic model is suggested,its detailed definition given and the performance analysis and comparison made of the switch fabric in Optical Burst Switching（OBS） by using this model and by the conventional non-bursty assigned traffic model.The calculation results show that when the fanout ratio of the switch fabric F=1 and the bursty intensity Bi=2,the packet loss rate under the burst assigned traffic model will increase by about one order of magnitude than under the non-bursty assigned traffic model.Perhaps the new bursty assigned traffic model cannot be used to reflect the traffic flow in reality,but it offers an analytical approach of approximation to the real traffic flow.关键词：optical burst switch（OBS）;bursty assigned traffic model;switch fabric
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- 32
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发布时间： - 摘要：A Dynamic Bandwidth Allocation（DBA） algorithm supporting the multiple services in Gbit/s EPON is proposed in this paper,which eliminates the unused time slots and HOL blocking in EPON by reporting the total frame amount under a single threshold and dynamically adjusting the threshold.A deepgoing study and analysis are made of the key parameter,i.e.the relationship between the assigned cycle time and the algorithm performance,for conducting the design of the assigned cycle time by the algorithm.关键词：unused time slots;Head of Line（HOL） blocking;multiple services;EPON;DBA
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- 112
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发布时间： - 摘要：Starting from the nonlinear Schrdinger equation describing the propagation of Dispersion-Managed Soliton（DMS） in optical fibers,the expression for the gain spectrum of the Modulational Instability（MI） in the DMS system is deduced and its numerical simulation results given,which show that the stronger the dispersion-map intensity,the greater the control of the gain in the MI process and the greater the path-average dispersion,the more evident the control of the gain in the process.关键词：dispersion management;modulational instability;fiber-optic communication
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- 88
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- 2
发布时间： - 摘要：The study of Photonic Crystal Fibers（PCF） is currently a hot pot issue in the area of optical devices and their extraordinary performances have injected new life into the novel optical devices.This article describes the latest advances in the study of PCF at home and abroad in respect of processes,attenuation and splicing and introduces the important applications and the latest new achievements of PCF in high power fiber lasers,fiber amplifier,super-continuum spectrum,femtosecond lasers,all-optical switches and dispersion compensators and other optical devices and presents the trend of its development.关键词：PCF;optical device;fiber laser;super-continuum spectrum
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- 397
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发布时间： - 摘要：Simulation technique is used to investigate the generation and distribution of Ultra-Wideband（UWB） pulse signals in fiber-optic transmissions.The numerical analysis of the system frequency response shows that it has the band-pass filter characteristics at lower frequency band and the shorter the central wavelength,the wider the lower frequency bandwidth.Transmission performance simulation for 12.5 Gbit/s pseudo-random sequence also shows that Gaussian pulse signals in time domain after fiber-optic transmission is close to FCC UWB pulse waveform template,while the signal spectrum in frequency domain to FCC spectrum specification.关键词：radio over fiber;ultra-wideband;fiber-optic transmission;phase modulator
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- 104
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发布时间： - 摘要：In this paper,a novel monolithically integrated two-port optical transceiver for FTTH is studied,its direct modulation response with relation to its structure and performances analyzed,and its relaxation oscillation,gain suppression and frequency chirp calculated.Furthermore,its direct modulation,frequency limitation and output optical field expression under the effect of the frequency chirp are obtained,and its output optical spectrum under the effect of high-frequency direct modulation frequency chirp simulated and analyzed.关键词：FTTH;optical transceiver;direct modulation;relaxation oscillation;gain suppression;frequency chirp
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- 116
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发布时间： - 摘要：In this paper,the Rouard’s method,which is widely used in the thin film optics and the calculations of waveguide grating theory,is introduced into the calculations of the band-gap structures of one-dimensional photonic crystal and the causes for the generation of photonic band-gap explained in light of the multi-beam interference theory of physical optics.The relevant formulas of Rouard’s method are derived in detail and the Rouard’s method is used to calculate the reflectance spectrum of the one-dimensional photonic crystal with different structures.The results show that the Rouard’s method is effective,clear in physical concepts and concise in formaula expression.关键词：one-dimensional photonic crystal;band-gap structure;Rouard’s method
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- 126
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发布时间： - 摘要：By optimizing the various parameters of the Er-doped fiber,using two 980 nm LDs as the pump source and making a fiber loop mirror with a 3 dB coupler,we develop a stabilized high-power wideband superfluorescence fiber source,which is configured in a two-stage double-pass forward pump structure.and has a power as high as 52.8 mW（17.15 dB）.Its 3 dB bandwidth can reach up to 40 nm without the use of any filter.This superfluorescent fiber source has been applied in the oil gas pipeline detecting project successfully.关键词：Superfluorescent Fiber Source（SFS）;Fiber Loop Mirror（FLM）;Amplified Spontaneous Emission（ASE）
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发布时间： - 摘要：The chip of the four-quadrant InGaAs APD in this paper is designed in a frontal incident planar structure and its material part is an SAGM APD.On the basis of systematical analysis and calculation of its important parameters,such as response time,dark current and responsivity,the optimized structural and the technological parameters are given.The test results show that its response time is ≤1.5 ns,responsivity ≥9.5 A/W and dark current ≤40 nA.As the PN junction and multiplication layer are set under the surface of the device in the reliability design,the surface leakage current can be effectively restrained and the reliability of the device improved.关键词：InGaAs APD;SAGM-APD;spectrum response range;responsivity;Dark current
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- 390
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- 3
发布时间： - 摘要：PSTN/ISDN emulation subsystem is one of the NGN service control subsystems.There are two PES architectures,call server-based emulation and IMS-based emulation.Each of them has its own advantages and disadvantages.In this paper,the two architectures are briefly introduced and the comparison and analysis of them made in respect of core architecture,service providing method and evolution scenarios.Finally,suggestions for the scheme selection are given on the basis of the status quo and development of telecom networks in China.关键词：PSTN/ISDN emulation;IP Multimedia Subsystem（IMS）;NGN;softswitch
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- 40
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发布时间： - 摘要：In this paper,the TH-PPM UWB signal is introduced and the BER formula of the overlapped and orthogonal signal-based system under the AWGN channel and multi-path conditions derived.The simulation results show that under the AWGN channel condition,the overlapped pulse signal-based TH-BPPM system has better performances than the orthogonal pulse signal-based system,while the orthogonal TH-BPPM system performance under the multi-path condition is superior to that under the AWGN channel condition.关键词：UWB;TH-BPPM;overlapped and orthogonal signal;BER
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- 65
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发布时间： - 摘要：Synchronization is a key technology in OFDM applications.The training sequence-based Schmidl&Cox（S&C） synchronization algorithm is studied,which is improved in view of its high estimation error by adding the calculation points and smoothing the maximum value.MATLAB simulation and analysis show that although the calculation amount is somewhat increased,fluctuations of the symbol synchronizations are effectively reduced and the synchronization performance remarkably improved in low SNR.关键词：OFDM;symbol synchronization;training sequence;maximum likelihood
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发布时间： - 摘要：This paper first briefly introduces the Ad Hoc network,then analyses the main differences between the Ad Hoc network and the existing communication systems in route selection,presents the classification of its routing protocols and introduces a few typical ones.Finally,it predicts the main orientations of the research on the Ad Hoc network protocols in the future.关键词：Ad Hoc;wireless packet network;routing protocol.
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发布时间： - 摘要：A monitoring and transmission system for the physical parameters of moving objects in adverse environment is constructed and the design methods for the optical communications model of the dynamic interconnections between moving and static light sources in the system discussed.The count of the communication windows of the system,software design concept and solutions to some key problems are described in detail and the field system test results reported in the conclusion.关键词：transient wireless optical communication;communication window;signal measurement;moving object
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发布时间： - 摘要：Optical path resource management is the core of telecom network resource management and its realization is a trend of modern communication network construction.Designed on the basis of the excellent domestic GIS platform-MAPGIS,the optical path resource management system effectively combines the characteristics of spatial distribution of optical path with the advantages of geographic information systems in spatial information expression.It does not only realize the dynamic management of its spatial and attribute data,but also supports its graphic configuration,facilitating the planning and maintenance of optical networks and greatly improving the optical path resource management.关键词：GIS;optical path;resource management system;interface
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