最新刊期
卷 ， 期 2 ， 2007
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- 摘要：In this paper,wavelength assignment in WDM optical networks with dynamic traffic is studied and a fair priority-based dynamic threshold algorithm for wavelength assignment without wavelength conversion proposed.By using this algo-rithm,the difference in blocking rates among lightpath connection requests for different distances is reduced by updating the ini-tial priority levels and fairness in the wavelength assignment improved.Simulation results show that the proposed algorithm is effective.关键词：WDM;wavelength assignment;fairness
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发布时间： - 摘要：A heuristic algorithm based on D * principle is proposed for the dynamic Routing and Wavelength Assignment（RWA） in WDM networks.On the basis of comprehensive considerations of the cost of each edge and the current use of wave-lengths in the network,the evaluation function of D* algorithm is constructed,achieving efficient assignment of the dynamic traffics in WDM networks.The simulation results show that this algorithm can effectively reduce the blocking rates,promote the rational assignment of the wavelength resource and at the same time its rapid and intelligent performances enhance the net-work survivability in a faulty environment.关键词：WDM networks;RWA;D* algorithm;simulation;blocking rate
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发布时间： - 摘要：The authors first describe the aim of constructing local mobile transmission networks and then describe the conditions required for adopting ASON technology in such networks on the basis of their present status and finally present the strategies for ASON deployment in the existing local mobile transmission networks and a mixed networking scheme of ASON with the convenional SDH networks.关键词：ASON;local transmission network;control domain
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发布时间： - 摘要：The nonlinear propagation characteristics of exponential optical pulses with initial linear frequency chirps in an anoma-lous-dispersion single mode fiber are numerically studied and compared with those of hyperbolic secant pulses.The effect of the negative chirp on pulse broadening is greater than that of the positive chirp when pulse amplitudeA =1 and the exponential pulse is more sensitive to the impact of the chirp than the hyperbolic secant pulse.WhenA >1.2,the pulse width oscillates in a periodically damped manner with the propagating distance and the period and amplitude of the oscillation increase with the in-crease of chirp parameter| C |when| C |≤2.The exponential pulse finally evolves into an optical soliton and the minimal value Arequired for this evolution is larger than that of hyperbolic secant pulse.关键词：fiber optics;frequency chirp;numerical analysis;exponential optical pulse
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发布时间： - 摘要：Matlab is used in performing power design,computation and distribution for the 60 GHz RoF system by the separa-ted up-and down-link positive sequence method,including the optical power design for its optical components,the electrical power estimation for its wireless transmission parts and the SNR analysis for the major receiving spots of its uplinks.Necessary analysis is made of the realizability,rationality and stability of the system through the power distribution design.Finally,a practical and feasible 60 GHz RoF system is set up in accordance with the design plan and power computation results.关键词：60 GHz RoF system;responsibility;modulation degree;path loss
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发布时间： - 摘要：A Multiple Importance Sampling（MIS） theory for first order Polarization Mode Dispersion（PMD） is introduced.Different biasing distributions are discussed on the basis of different configurations in first order PMD simulations.The simula-tion results show that by the MIS technique,extremely low probability（10-17） events can be obtained and the simulation effi-ciency is greatly improved as compared with the standard Monte-Carlo techniques.Furthermore,by contrasting the simulation results of different biasing distribution functions in importance sampling,different biasing distributions for the different system configurations are given.关键词：MIS;PMD;differential group delay（DGD）;biasing distribution
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发布时间： - 摘要：Effects of first-order nonlinearity and dispersion on super-Gaussian pulse propagation in single-mode optical fibers are numerically investigated.The results show that super-Gaussian oscillations caused by positive higher-order dispersion3βcome forth near the peak and trailing of the back edge of the pulse,while those caused by the negative3βappear near the peak and trailing of the front edge of the pulse.The greater the shape parametermof the pulse edge,the greater the peak value of the super-Gaussian pulse caused by the first-order nonlinearity and the second-order dispersion at the initial phase of the propaga-tion,and the narrower the pulse width and,at the same time,the longer the propagation distance,the smaller the peak value,the wider the pulse width and the greater the chirp,while the smaller them,the better the linearity of the chirps over a fairly large region around the center of the pulse.关键词：super-Gaussian pulse;one-order nonlinearity;dispersion;transient frequency chirp
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- 333
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发布时间： - 摘要：With the constant development of the intelligent and diversified element equipment in telecom networks,it has become in-creasingly important to unify the requirements on the Element Management System（EMS） interfaces.Mainly on the basis of Telecom Management Forum（TMF） specifications and CORBA technology,analysis is made of the design and implementation of the interfaces between the Optical Line Protection（OLP） EMS and the upper layer NMS.关键词：NMS;EMS;northbound CORBA interface;OLP
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发布时间： - 摘要：The managed Device and Cable（DC） resource and the related functions in the existing 97 system of China Telecom need to be migrated into GIS-based resource management system（i.e.China Telecom Network Resource Management System） by certain means for unified management.This process is called 97 DC resource rebuilding.This paper focuses on the introduc-tion of the design concept and functions of the interface between the resource management system and the 97 system and pro-vides a practical proof for the data migration and function implementation of the DC resource rebuilding.关键词：China Telecom network resource management system;97 system;interface
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发布时间： - 摘要：In Data Base（DB） cluster systems,process migration technology is often used for system load balancing,efficient fault tolerance and communication overhead reduction,etc.In this paper,we propose an ACE-based process migration techno-logy to realize kernel-level process migration functions at the user layer,solving the problem of across-platform process migra-tion in DB cluster systems and enhancing their data processing and system fault tolerance capabilities.关键词：ACE;process migration;across-platform;DB cluster
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- 93
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发布时间： - 摘要：As one of the important devices for NGN,Signaling Gateway（SG） must have High Availability（HA） of 99.999% to meet the QoS requiremets of telecom operators and users.Based on the introduction of the CPCI platform,this paper intro-duces and analyses two schemes for achieving HA signaling gateways——load balance and active/standby,and compares their advantages and disadvantages.关键词：NGN;softswitch;HA;SG;CPCI
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发布时间： - 摘要：This paper focuses on the analysis of the route convergence of Internet Border Gateway Protocol（BGP）,describes several solutions to this issue currently proposed in this area and points out their respective problems.The authors present their view that BGP route convergence is related to multiple factors,such as routers having different routing policies,different time delay in BGP data update,different orders of link connection failure and recovery and different granularity of route update mes-sage,and it is necessary to devise an integrated solution.关键词：BGP;convergence;police;route
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- 167
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发布时间： - 摘要：In this paper,we mainly discuss the mathematical modeling and performances of the Random Access Channel（RACH） of the wireless cells in WCDMA networks.We first introduce RACH and the message transfer of WCDMA net-works.Then we describe the slotted ALOHA access procedure of the RACH access process and,on this basis,we lay special stress on analyzing the method and detailed procedure of RACH mathematical modeling and give the calculation formula for its throughput.Finally,we make analysis of its performances.关键词：WCDMA;RACH;slotted ALOHA;mathematical modeling;performance analysis
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- 259
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发布时间： - 摘要：The structrure of the fiber-optic Michelson interferometer system is first introduced.Then the structure and operat-ing principle of the fiber-optic polarization controller and the control of the polarizing state of the system sensing arm described and the principle of interference between the signal light and the reference light in the system and the factors affecting the inter-ference light intensity given.Finally,its applications are presented.关键词：fiber-optic polarization controller;fiber-optic interferometer;interference principle
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发布时间： - 摘要：In this article,a highly nonlinear photonic crystal fiber with a pure silica core is designed and fabricated,of which the core diameter is 1.65μm,the air hole diameter 4.75μm,the space between the hole centers 5.35μm,the zero dispersion wavelength 1 120 nm and the dispersion at wavelength of 800 nm-88 ps/（nm.km）.Supercontinuum emission with a smooth spectrum stretching from 450 to 1 400 nm is obtained by injecting 30 fs Ti: sapphire laser pulses with an energy of up to 5 nJ,a pulse repetition rate of 100 MHz and a central wavelength of 800 nm into 2 meters of such a photonic crystal fiber.关键词：photonic crystal fiber;nonlinear;femto-second laser;supercontinuum spectrum
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- 409
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发布时间： - 摘要：The Double-Clad Fiber（DCF） with truncated inner cladding has much better absorption efficiency to optical waves than DCF with circular inner cladding.Owing to the limitation of the ray method in analyzing the field distribution and transmit power of optical waves in fibers,we decide to apply waveguide theory for analyzing DCF with truncated inner cladding in an at-tempt to find out the divergences of different types of DCF with truncated inner cladding in absorption efficiency in unit dis-tance.关键词：DCF;truncated inner cladding;absorption efficiency;waveguide theory
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发布时间： - 摘要：First of all,this paper brings forward problems of silica single-mode fibers in high-rate large-capacity long-haul fibre-optic telecommunications.Then,it introduces the structural characteristics and transmission mechanism of the Photonic Crystal Fiber（PCF） and briefly depicts its development history and the latest research achievement.Finally,it reviews its transmission properties,such as attenuation,dispersion and nonlinearity.关键词：silica fiber;Single-mode fiber;photonic crystal fiber
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- 337
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发布时间： - 摘要：By using LabVIEW virtual instrument technique,a wavelength auto-measurement and control system for Sampled Grating DBR（SG-DBR） lasers is developed.This system can automatically implement current scanning for SG-DBR laser,col-lect and analyze its output spectrum data,and generate its“wavelength-current”look-up table,by which the control of the out-put wavelength of the SG-DBR laser is realized.关键词：SG-DBR laser;wavelength measurement;wavelength control;virtual instrument
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发布时间： - 摘要：In this paper,we first introduce the basic operating principle of Thulium-Doped Fiber Amplifier（TDFA） and Gain-Shifted TDFA（GS-TDFA） and analyze different pumping wavelength options.Then,we propose a dual-stage GS-TDFA scheme,in which high concentration doping TDF and laser diode pumps are used.The prototype fiber amplifier in this struc-ture achieves optical gain greater than 20 dB,saturated output power higher than 17 dBm and NF in the range of 5.9-6.2 dB in 30 nm operating bandwidth.关键词：TDFA;GS-TDFA;S-band
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- 198
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发布时间： - 摘要：The transient dynamics of EDFA have become an important factor affecting the performances of DWDM networks.In this paper,the basic principle of Auto Gain Control（AGC） in EDFA is described,several current AGC technologies for transi-ent dynamics of EDFA and the typical implementation schemes summarized and their advantages and disadvantages compared.Finally,the views of the development of AGC technologies in the future are presented.关键词：EDFA;transient dynamics;Auto Gain Control（AGC）;DWDM
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发布时间： - 摘要：As interleavers have a fairly high cost-performance,they have been extensively used in narrow interval DWDM sys-tems.This paper introduces a kind of technology,by which a new type of polarization delay structure is used to manufacture narrow-channel-interval interleavers,which are characteristic of small in insertion loss,polarization dependent loss and polari-zation mode dispersion,and easy in assembly.In addition,the paper describes in detail the basic theory and design concept of the polarization delay structure and the structure of the interleaver manufactured thereby.关键词：polarized light;interference;beam splitter;phase delay;temperature compensation;Interleaver
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