最新刊期
      卷 ， 期 5 ， 2007
      • Xu Bo1,Ding Hong2
        Issue 5, Pages: 1-3(2007) DOI: 10.13756/j.gtxyj.2007.05.003
        摘要：This paper proposes a Low-Density Parity-Check（LDPC） code,which is simple in structure and easy in encoding,as a Super Forward Error Correction（FEC） code for fiber-optic communication systems.Its decoding performance in fiber paths is simulated and verified.Compared with the commonly used RS（255,239） FEC code,the proposed LDPC code with the same code efficiency can achieve about 2 dB coding gain at a code length of 4 080 higher than RS code.  
        关键词：fiber-optic communication;FEC code;LDPC code;iterative decoding   
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      • Yao Yu,Zhao Yongli,Zhang Yongjun,Gu Wanyi
        Issue 5, Pages: 4-7(2007) DOI: 10.13756/j.gtxyj.2007.05.004
        摘要：As Ethernet Passive Optical Network（EPON）is one of the most effective ways for broadband access,it is important to set up a stable and effective network management system.This paper gives a brief description of the EPON structure and presents the design plan for SNMP-based Network Management System（NMS）,taking into consideration the functions of configuration management,performance management,fault management and security management.Then it introduces Web server-based GUI for the system and explains its respective software realization at the manager and the agent.  
        关键词：EPON;SNMP;NMS;Web   
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      • Liu Yuxia,Sang Xinzhu,Yu Chongxiu,Xu Daxiong
        Issue 5, Pages: 8-10(2007) DOI: 10.13756/j.gtxyj.2007.05.005
        摘要：The principle of Raman Soliton Self-Frequency Shift（SSFS） in Highly Nonlinear Photonic Crystal Fiber（HNL-PCF） is analyzed and the applications of its effects on wavelength conversion,femtosecond soliton pulse source,superhigh speed DAC and communication systems stability improvement discussed.With the development of PCF technology and the deepening research on SSFS,various SSFS-based devices in PCF will play important roles in future fiber-optic communication systems.  
        关键词：soliton self-frequency shift;photonic crystal fiber;wavelength conversion;femtosecond soliton pulse   
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      • Xu Yi,Pan Hao,Fan Ge
        Issue 5, Pages: 11-14(2007) DOI: 10.13756/j.gtxyj.2007.05.006
        摘要：In this paper,we give the functional structure and layered view of GMPLS-based Optical Burst Switching（OBS） framework.With reference to the latest research developments at home and abroad,we compare various existing technologies for label space reduction and traffic engineering,and present possible solutions appropriate for GLOBS system and major technological points in future work.  
        关键词：Generalized Multi-Protocol Label Switching（GMPLS）;optical burst switching（OBS）;label-switched path;traffic engineering   
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      • Gui Lü,Zhang Yangan,Huang Yongqing,Li Ling,Ren Xiaomin
        Issue 5, Pages: 15-17(2007) DOI: 10.13756/j.gtxyj.2007.05.007
        摘要：This paper introduces a novel dynamic gain equalization system based on Optical Channel Monitoring（OCM） and DCE（Dynamic Channel Equalization） technologies and elaborates on its operating principle and the process of algorithm realization.Compared with the existing system,this system is characteristic of dynamic,real-time and high-speed responses.Its functions and performances are experimentally verified.  
        关键词：OCM;DCE;ROADM   
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      • Mao Yingchao,Sun Fengjie,Ma Yonghong
        Issue 5, Pages: 18-20(2007) DOI: 10.13756/j.gtxyj.2007.05.008
        摘要：There are many dispersion compensation technologies used in fiber-optic communications.The paper investigates two types of dispersion compensation schemes: Dispersion Compensation Fiber（DCF） and Chirped Fiber Grating（CFG） and realizes unrepeatered transmissions over 198 km and 220 km G.652 fibers respectively by numerical simulation.The simulations prove that the transmission distance can be improved by about 10% by using CFG dispersion compensation and when BER is 10-12,the power penalty for errorless transmission induced by the dispersion compensation after 220 km is only 1.6 dB.  
        关键词：chirped fiber grating;dispersion compensation;unrepeatered transmission;fiber-optic communication   
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      • Zhang Wen,Sun Shanlin
        Issue 5, Pages: 21-22(2007) DOI: 10.13756/j.gtxyj.2007.05.009
        摘要：Polarization Mode Dispersion（PMD） is one of the factors that has fairly large impacts on high-speed long-haul fiber-optic transmission systems.This article expounds the influences of PMD on the fiber-optic communication system,establishes the theoretical model,analyzes and discusses the higher-order PMD and its compensation while analyzing the limitations of the single channel 1st-order compensation method,presents 2nd-order PMD compensation method and conducts the research on this method.  
        关键词：PMD;PSP;compensation   
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      • Li Jianyuan
        Issue 5, Pages: 23-26(2007) DOI: 10.13756/j.gtxyj.2007.05.010
        摘要：This paper analyzes the schemes for the generation of electronic analog switch-and mixer-based Carrier Suppressed Return-to-Zero（CSRZ） code by using a single-stage modulator and presents a relevant precoder-based generation method,which is simple and easy to integrate.Simulation verifies that the CSRZ code generated by this method has narrower modulation spectrum width（about 15 GHz） and stronger dispersion tolerance（as much as ±1 320 ps/nm） as compared with that by the traditional methods（e.g.cascaded modulators）.  
        关键词：CSRZ;modulation format;M-Z modulator   
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      • Ding Ying,Pan Wei,Luo Bin,Zhou Shu
        Issue 5, Pages: 27-29(2007) DOI: 10.13756/j.gtxyj.2007.05.011
        摘要：As single Optical Hard Limiter（OHL）-based synchronous OCDMA system cannot be entirely immune from channel crosstalk,double OHL structure is introduced to optimize the system transmission performance.This paper presents the relationship between the code weight of address code,spectrum intensity,number of users and the bit error probability and that between the normalized throughputs of the synchronous and asynchronous systems.The results show that when the number of users is quite different from the address code weight,the bit error probability of the double OHL-based synchronous OCDMA system remarkably drops and produces higher normalized throughput than the asynchronous system.  
        关键词：OCDMA systems;synchronous;prime sequence;OHL;bit error probability   
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      • Si Wei,Chen Mu
        Issue 5, Pages: 30-32(2007) DOI: 10.13756/j.gtxyj.2007.05.012
        摘要：NGN is advancing rapidly.With the large scale development of NGN and 3G services in the next few years,the construction of the next generation carrying networks will be the key to the success in the growth of telecommunications services.This paper analyzes and presents the considerations of the construction of NGN carrying networks in respect of QoS,reliability,security and address planning.  
        关键词：next generation carrying network;QoS;reliability   
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      • Huang Rui,Zou Chen
        Issue 5, Pages: 33-35(2007) DOI: 10.13756/j.gtxyj.2007.05.013
        摘要：Code Orthogonal Frequency Division Multiplexing （COFDM） is a multi-carrier digital communication modulation technology.Its basic principle is to divide a wideband frequency channel into multiple overlapping subchannels for narrowband transmission.Despite of the spectral overlap,the signals on the subchannels can be correctly separated at the receiver side as long as they are orthogonal.This dissertation focuses on the research on the synchronization technology in COFDM communication systems.  
        关键词：COFDM;sampling clock synchronization;symbol synchronization   
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      • Liu Fangnan1,Sun Lijun2,He Zhuorong2,Zhang Yuke2
        Issue 5, Pages: 36-38(2007) DOI: 10.13756/j.gtxyj.2007.05.014
        摘要：This article introduces a new design of optical transceiver that can transfer MIL-STD-1773 protocol independently.Adopting DC coupling and supporting working in burst mode,the transceiver is characteristic of low receiving sensitivity（≤-20 dBm）,high dynamic range（≥10 dB） and long transmission distance.The paper focuses on its application background,design method,operation principle,control-circuit design,analysis of output curve and principal test parameters.  
        关键词：1773 data bus;optical transceiver;control-circuits;sensitivity;dynamic range   
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      • Dong Hongjun,Zhang Yinfa
        Issue 5, Pages: 39-41(2007) DOI: 10.13756/j.gtxyj.2007.05.015
        摘要：On the basis of the analysis of the depolarization effect of Polarization Mode Dispersion（PMD） on the measurement of the polarization-nulling method,a simple configuration that provides OSNR information using polarization scrambling and orthogonal polarization detection is proposed and demonstrated.The polarization scrambler that can scramble the input polarization state to cover the Poincare sphere is shared by many Wavelength Division Multiplexing（WDM） channels.After the demultiplexer,the desired channel will be split into two arms using a Polarization Beam Splitter（PBS） and OSNR are obtained from interaction terms between two orthogonal polarization arms.The veracity of the improved scheme is verified by simulation.  
        关键词：monitoring;polarization;OSNR;PMD;ASE noise;DGD   
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      • Hu Xianzhi1,Lin Peifeng2
        Issue 5, Pages: 42-44(2007) DOI: 10.13756/j.gtxyj.2007.05.016
        摘要：This paper first presents the necessity of studying bending loss-insensitive single mode fibers（ITU-T G.657） on the basis of the features of access network construction.Then it describes their structural features and property parameters and briefly summarizes the different uses of G.657A and G657B fibers.Finally,it compares them in property parameters,such as mode field diameter,cut-off wavelength and bending loss.  
        关键词：access network;silica glass;single mode fiber;G.657 fiber   
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      • Wu Ming1,Liu Hairong1,Huang Dexiu2
        Issue 5, Pages: 45-46(2007) DOI: 10.13756/j.gtxyj.2007.05.020
        摘要：In this paper,we numerically analyze the photonic crystal fibers（PCF） with different structural parameters by using the FullVectorial Finite Element Method（FVFEM）,achieving the fundamental mode field distribution.Then we calculate and obtain the effective area Aeff and the nonlinear coefficient γ,two important basic physical quantities of the nonlinear properties of highly nonlinear PCF.Finally,we analyze the relationship between Aeff and γ and its hole diameter d and the pitch Λ.  
        关键词：PCF;FVFEM;effective area;nonlinearity coefficient   
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      • Ren Dengjuan,Chen Mingsong,Huang Xueming
        Issue 5, Pages: 47-49(2007) DOI: 10.13756/j.gtxyj.2007.05.001
        摘要：The structure and performance parameters of coplanar waveguide electro-optic modulator with thicker electrodes and buffer layer are analyzed using the extended point-matching method.The relationship between the parameters and the modulation characteristics is obtained from selecting by simulation the proper thickness of the electrodes and buffer layer,optimizing the modulator performance and realizing broadband modulation.The results agree well with those obtained by using the conformal mapping method.This method provides a simple and fast approach to the analysis of the multi-layered structures with finite electrode thickness.  
        关键词：Electro-optic modulation;coplanar waveguide;extended point-matching method;broadband modulation   
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      • Xiao Caixia,Li Xihua,Zhou Qiang,Yang Jiangyi,Jiang Xiaoqing,Wang Minghua
        Issue 5, Pages: 50-52(2007) DOI: 10.13756/j.gtxyj.2007.05.021
        摘要：A novel design scheme for digital optical switch with high extinction ratio by employing S curve waveguide at the end of the Y branch is proposed.Higher extinction ratio than that of the device without S curve waveguide is obtained by applying certain synchronous voltage to the Y branch and the curve electrode of the S curve waveguide.Finite Difference Beam Propagation Method（FDBPM） is used to simulate the performance of the design,and the results show that the extinction ratio can exceed-25 dB with the switch voltage of about 8 V at 1.55 μm.  
        关键词：digital optical switch（DOS）;asymmetrical electrode;S curve waveguide;Lithium niobate   
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      • Ma Chao,Qiao Xueguang,Jia Zhenan,Feng Fei,Yang Heqian,Zhang Lei
        Issue 5, Pages: 53-55(2007) DOI: 10.13756/j.gtxyj.2007.05.022
        摘要：Made up of Fiber Bragg Grating（FBG）,the geophone collects,modulates and demodulates directly the sensing information embodied in wavelengths.It has the advantages of higher resolution,higher accuracy,better immunity against interference and wider bandwidth.In this paper,the FBG-based geophone is described and its principal parameters given.A new demodulation scheme for the geophone is presented,which provides the basis for its study and practical applications.  
        关键词：Fiber Bragg Grating（FBG）;geophone;vibration sensor   
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      • Li Xinhua1,Chen Zuolong2,Fan Zhongli2
        Issue 5, Pages: 56-57(2007) DOI: 10.13756/j.gtxyj.2007.05.017
        摘要：Based on full IP core network architecture,commercialized IP Multimedia Subsystem（IMS） provides high QoS to the users,which relies to a large extent on the IP backbone network.Integrated Generalized Multiprotocol Label Switching（GMPLS） is the core technology for the next generation backbone network.Using traffic engineering technology,it provides high QoS.This paper expounds the realization of high QoS of IMS by using GMPLS and analyses the realization methods.  
        关键词：IMS;GMPLS;QoS   
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      • Wang Shentao,Zhou Xi,Yang Hao
        Issue 5, Pages: 58-62(2007) DOI: 10.13756/j.gtxyj.2007.05.019
        摘要：Energy efficiency is a key issue for Ad Hoc networks.Power-aware routing protocol is a way to reduce power consumption and optimize network performance.In this paper,some power-aware protocols proposed in recent years are classified and respectively described,and future research directions for such routing protocols are pointed out.  
        关键词：wireless Ad Hoc network;power-aware;routing protocol   
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      • Lei Hubao,Lin Jiming
        Issue 5, Pages: 63-66(2007) DOI: 10.13756/j.gtxyj.2007.05.018
        摘要：In view of power inefficiency and high noise vulnerability in conventional transmitted-reference UWB systems,a low complexity Dirty Template（DT） receiver is developed,which receives the demodulation signals extracted by using multiple decided received waveform of the data symbols,considerably lowering the noise level in the self-derived template waveform and improving the overall detection performance.There is little loss in energy efficiency as no-reference pilots are required.The performances of the receiver are analyzed and the theoretical deduction verified by simulation results.  
        关键词：ultra-wideband;transmit-reference;energy capture;Rake receiver   
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      • Chen Xiaoqiang1,Lu Mai2,Xue Deqiang2
        Issue 5, Pages: 67-69(2007) DOI: 10.13756/j.gtxyj.2007.05.002
        摘要：Using finite-difference method for the Helmholtz equation,this paper investigates the influence of the ridge in a novel single-ridge rectangular waveguide on the transmission characteristics of the waveguide when the ridge is in the central part and its dimensions vary.It calculates the cutoff wavelength λc and single-mode bandwidth B（λc /λc1） when the ridge dimensions vary and gives the field patterns of TE10 mode and TE11 mode and the curve corresponding to the relevant effects of the transfiguration.By comparing with the conventional waveguide,it points out the advantages and disadvantages of the new single-ridge rectangular waveguide.  
        关键词：Helmholtz equation;finite-difference;transmission characteristics;cutoff wavelength;single-mode bandwidth;field pattern   
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