最新刊期
      卷 ， 期 6 ， 2006
      • Liu Haiyu,Li Jian,Ren Tao,Gu Wanyi,Xu Daxiong
        Issue 6, Pages: 1-4(2006) DOI: 10.13756/j.gtxyj.2006.06.001
        摘要：Several migration models existing in the process of upgrading IP/MPLS-based networks to GMPLS-based networks are studied,with the emphasis on the analysis of some island models.At the same time,the problems existing in the interconnections between these two kinds of networks,the differences between MPLS and GMPLS and the routes,signaling and the path computation technology adopted in solving these problems are analyzed.  
        关键词：MPLS;GMPLS;PSC;LSP;path computation   
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      • Zhang Pei,Li Meng,Yang Guirong,Gu Wanyi
        Issue 6, Pages: 5-7(2006) DOI: 10.13756/j.gtxyj.2006.06.002
        摘要：With the explosive growth of data traffic,how to utilize the precious bandwidth resources in the optical network has been the focus of attention of the network operators.As a new service in ASON,SBS can be considered as a specific realization of the traditional BoD.It can effectively save the bandwidth resources for the operators and reduce the expenses for the users.This paper expatiates on the management mode,realization and social values of SBS in ASON.  
        关键词：SBS;ASON;VCAT   
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      • Zhang Lijuan~1,Li Weimin~1,Zhang Chunmin~2,Chen Fudu~1
        Issue 6, Pages: 8-10(2006) DOI: 10.13756/j.gtxyj.2006.06.003
        摘要：On the basis of comprehensive considerations of multiple factors and improvement of burst offset time,we propose a novel contention resolution and QoS provisioning scheme in optical burst switching（OBS） networks.By using three channel scheduling algorithms,namely Least Recently Used（LRU）,First Fit（FF） and Priority Set（PS）,we simulate and compare the proposed scheme with the preemptive prioritized just enough time（PPJET） contention resolution scheme.It is found that our scheme obviously outperforms the latter in burst loss.  
        关键词：optical burst switching（OBS）;burst-loss;Quality of Service（QoS）   
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      • Liu Xiaoming~1,Zhu Hao~2
        Issue 6, Pages: 11-13(2006) DOI: 10.13756/j.gtxyj.2006.06.004
        摘要：In IP-based networks,VoIP has become the representative technology of the next generation voice system,but its QoS is limited by the IP network capacity.Now MPLS is regarded as a most promising technology for high-speed backbone networks.By MPLS,layer 3 routing can be well complemented by layer 2 switching,which guarantees the point-to-point QoS.Network performance can be further optimized by the combination of DiffServ and QoS of MPLS.  
        关键词：VoIP;MPLS;QoS;DiffServ   
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      • Zhang Peng~
        Issue 6, Pages: 14-16(2006) DOI: 10.13756/j.gtxyj.2006.06.005
        摘要：The rapid advance and extensive applications of WDM technology have brought about a constant increase in the size of the crossconnection in optical works as well as the complexity of their structure.In order to reduce the switching and transmission cost in the optical domain of WDM networks,WaveBand Switching（WBS） has been proposed,for which considerable research has been conducted.In this paper,we introduce some basic concepts of WBS and Multi-Granular Optical Cross-connect（MG-OXC） and present a new type of MG-OXC structure.  
        关键词：WDM;WaveBand Switching（WBS）;Multi-Granular Optical Cross-connect（MG-OXC）   
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      • Zhang Ruihua,Liu Guohui
        Issue 6, Pages: 17-18(2006) DOI: 10.13756/j.gtxyj.2006.06.006
        摘要：This paper introduces a UIP TCP/IP stack-based scheme for the design of the embedded test & control network access module in optical devices.As a cost-effective solution for the access to the test & control network,the module can easily and directly connect the control devices with RS-232/RS-485（serial communication interface） and other interfaces to the local area network（LAN） so as to make full use of its abundant and existing resources and form a series of distributed test and control systems.  
          
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      • Peng Liangfu
        Issue 6, Pages: 19-21(2006) DOI: 10.13756/j.gtxyj.2006.06.007
        摘要：The applications of WDM technology in HFC networks are investigated with the emphasis on those of DWDM to the downstream and CWDM to the upstream of the networks.The research results indicate that DWDM is more appropriate for the downstream of the network,extending its transmission distance,while CWDM more appropriate for the upstream,increasing its upstream bandwidth.The application of WDM technology can realize bidirectional transmissions in HFC networks.  
        关键词：DWDM;CWDM;Hybrid Fiber Coax（HFC）network   
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      • Zhang Jiyong,Wang Aiguo
        Issue 6, Pages: 22-23(2006) DOI: 10.13756/j.gtxyj.2006.06.008
        摘要：In this paper,the basic structure and operating principle of ADPLL（All Digital Phase-Locked Loop） are first introduced,which is followed by the analyses of its mathematic model and the calculation of its main parameters.Then,a feasible low-jitter ADPLL circuit structure for SEC（SDH equipment clock）is designed and specific circuit analysis of and designs for each part of ADPLL made,which is optimized by appropriate CPU configurations.Finally,this circuit is verified by FPGA and the test result given.  
        关键词：ADPLL;Digital-Controlled Oscillator（DCO）;divider;jitter   
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      • Hu Baomin,Liu Wu,Lu Xi,Liu Hai,Liu Deming
        Issue 6, Pages: 24-27(2006) DOI: 10.13756/j.gtxyj.2006.06.009
        摘要：The multiple address technology,key physical layer technology and layer 2 protocols of EPON and WDM-PON are analyzed.The implementation of Point-to-Point Emulation（P2PE） of the above two technologies is specially analyzed in detail and their performances compared.Finally,a conclusion is given and their respective application fields indicated.  
        关键词：EPON;WDM-PON;TDMA;WDMA;P2PE   
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      • Yi Hanru,He Yan
        Issue 6, Pages: 28-30(2006) DOI: 10.13756/j.gtxyj.2006.06.010
        摘要：This paper first discusses the practical significance of implementing multicasting in EPON systems and then presents a scheme for achieving this goal by adopting IGMP Snooping on the basis of analysis and comparison of the existing layer two（L2） multicasting protocols and in connection with the characteristics of EPON itself.Finally,it explains in detail how OLT and ONU support the IP multicasting services.  
        关键词：EPON;multicast;IGMP   
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      • Wang Zhen~1,Yan Xianhua~2
        Issue 6, Pages: 31-32(2006) DOI: 10.13756/j.gtxyj.2006.06.011
        摘要：This paper introduces a distributed application server system in softswitch,which is a server group with a clear structure that consists of multiple single servers with unattached functions and can be turned into different service function combinations according to user requirements to fulfill various complicated call processing.The distributed system structure enables flexible configuration,greatly improved high availability and desired performances at the server level.This paper also describes a system realization method used in practical projects.  
        关键词：Application Server（AS）;distributed;high availability   
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      • Huang Yong~1,Yuan Xinchang~2
        Issue 6, Pages: 33-34(2006) DOI: 10.13756/j.gtxyj.2006.06.012
        摘要：The integrated Access Media Gateway（AMG） is placed in the access layer of the SoftSwitch-based NGN.Its High Availability（HA） has a direct impact on the QoS of telecommunication networks.The concept and realization of HA is first introduced and then an HA solution presented on the basis of the study of the architecture and functions of AMG.In respect of the hardware,its fault-tolerance function is realized by the active/standby redundancy mechanism with the critical data and parameters in warm standby,while for software,the over-all architecture for HA and the status mechanism for switchover are advanced.  
        关键词：AMG;softswitch;HA   
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      • Wang Yuqiang,Li Qi,Xu Ying
        Issue 6, Pages: 35-37(2006) DOI: 10.13756/j.gtxyj.2006.06.013
        摘要：With the advent of the information age and the rapid popularization and applications of new services and technologies,the emergency communication network is faced with the direct and urgent requirements for the modernization,standardization,simplification and automation of its operation,management and maintenance.This article mainly introduces the design of the resource management system of the transmission network,the basic network of the emergency communication specialized subnet and expatiates on the design principle,system design,data design,system components and function realization.  
        关键词：transmission network;emergency communication;GIS;design;realization   
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      • Cheng Xiang,Wang Feng
        Issue 6, Pages: 38-41(2006) DOI: 10.13756/j.gtxyj.2006.06.014
        摘要：In recent years,the virtual instrument technology has been widely used in scientific research and production.This paper elaborates on a scheme for the realization of a repeater Automatic Test System（ATS） by using the virtual instrument technology,including the composition of ATS,the construction of LAN-based testing networks,the use of the instrument driver and the configuration of I/O interfaces,and the applications of Agilent VEE Pro in the development of the testing software.  
        关键词：virtual instrument;repeater;instrument driver;Standard Commands for Programmable Instrument（SCPI）   
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      • Li Xinlin,Li Zhengbin,Wu Deming
        Issue 6, Pages: 42-44(2006) DOI: 10.13756/j.gtxyj.2006.06.015
        摘要：Polarization Mode Dispersion Emulator（PMDE） is an important device for the research in Polarization Mode Dispersion（PMD）.In this paper,a new design of PMDE is presented and the theoretical analysis and simulation of this emulator made,which proves that it generates tunable Differential Group Delay（DGD） and realizes ergodicity of the polarization state.  
        关键词：PMD;PMDE;ergodicity;tunable waveplate;rotator   
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      • Wang Jianfei,Wang Gaogang,Zhang Yixin
        Issue 6, Pages: 45-47(2006) DOI: 10.13756/j.gtxyj.2006.06.016
        摘要：Modeling of macrobend loss of standard multicladded monomode fibers is presented,which can be used for the calculations of the macrobend losses of both multicladded and monocladded monomode fibers.The impact of the bending radius and operating wavelength on the bending loss of monomode fibers is discussed and the macrobend loss model compared with the conventional core-infinite cladding model,which indicates that the cladding of the monomode fiber has an evident effect on the bend loss.Furthermore,the impact of the whispering-gallery mode on the bend loss oscillation is described in detail.  
        关键词：monomode fibers;bend loss;whispering-gallery mode   
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      • Chen Xinjie,Guan Hongyun
        Issue 6, Pages: 48-51(2006) DOI: 10.13756/j.gtxyj.2006.06.017
        摘要：The existing optical domain compensation methods for the Polarization Mode Dispersion（PMD） in fiber-optic transmissions are studied and compared.This paper presents a chirped-fiber-grating-based optical domain compensation scheme,which realizes the adaptive feedback PMD compensation.The chirped fiber grating is made of photosensitive polarization maintaining fiber by using the equivalent chirp technology,which is used as the delay line of the PMD compensator.It has been experimentally shown that,by this scheme,PMD in fiber-optic transmissions can be effectively compensated and the transmission quality of optical signals improved.  
        关键词：polarization mode dispersion（PMD）;chirped fiber grating;optical domain compensation   
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      • Zhang Cuihong~
        Issue 6, Pages: 52-55(2006) DOI: 10.13756/j.gtxyj.2006.06.018
        摘要：As a new technology for fiber dispersion compensation,Electronic Dispersion Compensation（EDC） is gradually being applied in practical projects.In this article,its general circuit structure and operating principle are introduced and analyzed and its compensation performance in 10 Gbit/s optical transmission systems verified by the system tests and the analysis of the test results.  
        关键词：Electronic Dispersion Compensation（EDC）;dispersion;BER;dispersion penalty   
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      • Cai Guoli,Jian Wei
        Issue 6, Pages: 56-57(2006) DOI: 10.13756/j.gtxyj.2006.06.019
        摘要：A theoretical method for Fiber Bragg Grating（FBG） temperature sensing has been proposed.Based on a temperature sensing model of FBG,a temperature sensing experiment is conducted at liquid nitrogen temperature（-196 ℃）.The theoretical and experimental results are compared and analyzed,which shows that at liquid nitrogen temperature or in large-scope temperature sensing,the relationship between the temperature variation ΔT and the relative shift of the reflected center wavelength ΔλB/λB of FBG is nonlinear and conic multinomial.  
        关键词：FBG;optical fiber sensing;temperature sensing;liquid nitrogen temperature   
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      • Li Shiyu,Tan Xudong,Huang Danhua,Yang Xianwen,Hu Haiming
        Issue 6, Pages: 58-60(2006) DOI: 10.13756/j.gtxyj.2006.06.020
        摘要：Brief computations are conducted of the reflection mechanism of the improved ROSA（Receiver Optical Subassembly） with tilted fiber stub end face.On this basis,theoretical analysis is made of the reflected optical path of this structure by using Gauss optics theory.Exclusive of the reflection factor of the physical contact surface,the relevant test results show a basic agreement with the theoretical analysis,which proves that this theoretical analysis can be applied in practice.  
        关键词：reflection;tilted fiber stub end face;Receiver Optical Subassembly（ROSA）   
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      • Chen Haohai,Wang Ying
        Issue 6, Pages: 61-63(2006) DOI: 10.13756/j.gtxyj.2006.06.021
        摘要：As insertion loss Error Function（EF） is the key parameter for the Gain Flatting Filter（GFF）,the real-time EF monitoring is vital for manufacturing GFF.The real-time EF monitoring system in this article is realized via General Purpose Interface Bus（GPIB） interface and the data is obtained from the spectrum analyzer and analyzed and processed by computer programming,which makes it possible to plot in real time the loss vs.wavelength curve with tolerance and monitor the EF.  
        关键词：EF;GFF;GPIB;EDFA;DWDM   
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      • Cai Qin
        Issue 6, Pages: 64-66(2006) DOI: 10.13756/j.gtxyj.2006.06.022
        摘要：In view of the problems in networking applications arising from the optical power budget limitation of Coarse Wavelength Division Multiplexing（CWDM） systems in MAN,Raman amplifiers and the relevant key technologies for WDM systems with wide operating wavelength range are introduced and the field test results in CWDM systems given.  
        关键词：CWDM;Raman amplifier;SOA   
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      • Huang Liyan,Lu Ji,Yin Xinda
        Issue 6, Pages: 67-70(2006) DOI: 10.13756/j.gtxyj.2006.06.023
        摘要：As is a new hardware device for network monitoring,TAP（Test Access Port） provides a method for obtaining the network traffic without disrupting the normal traffic.It can be used to implement a series of functions,e.g.performance monitoring,failure correction,traffic analysis and malicious attack prevention.This paper expounds its background,main features, operating principle and applications.  
        关键词：test access port;traffic access port;network monitoring   
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