最新刊期
      卷 ， 期 5 ， 2015
      • Tang Rui,Lai Junsen,Zhao Wenyu,Zhang Haiyi
        Issue 5, Pages: 1-3(2015) DOI: 10.13756/j.gtxyj.2015.05.001
        摘要：With respect to 400Gbit/s transmission performances and applications,this paper simulates and analyzes the transmission distance and spectrum efficiency based on different technical schemes,the incident power limitation and nonlinear effects.The results show that the requirements of backbone networks for over 1 000 km transmission can be met by using the4×100Gbit/s technology,whereas for the same purpose,the 2×200Gbit/s technology must be used in combination with lowloss fibers and new type of low-noise amplifiers.Metropolitan Area Networks（MAN）,data centers and other large bandwidth interconnections may take the lead in adopting 400Gbit/s,2×200Gbit/s or 4×100Gbit/s technologies to satisfy the general requirements for transmission capacity and distance.  
        关键词：400Gbit/s transmission;spectrum efficiency;nonlinearity;subcarrier   
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      • Li Yongqian,Li Pan,An Qi,Li Xiaojuan
        Issue 5, Pages: 4-7(2015) DOI: 10.13756/j.gtxyj.2015.05.002
        摘要：This paper studies in-depth the principle of the Vector Brillouin Optical Time Domain Analysis（VBOTDA）system.This system adopts a heterodyne detection scheme on the basis of the conventional BOTDA system,thereby enhancing the system Signal-to-Noise Ratio（SNR）and acquiring Brillouin phase-shift information.Then,it proposes a phase demodulation method,i.e.the spectrum algorithm that combines the superimposed average denoising algorithm with the FFT analysis.Theoretical analysis and experimental demonstration verify its feasibility and effectiveness in that it is effective in demodulating signals with different SNR and for signals with 0.3 Vamplitude and noise standard deviation of 0.5 V,and the phase relative measuring error can be lowered to 0.71% when the spectrum algorithm superimposed 1 000 times is used.  
        关键词：stimulated Brillouin scattering;VBOTDA system;phase demodulation;spectrum algorithm   
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      • Wang Xiaoling,Gao Li,Shen Gangxiang
        Issue 5, Pages: 8-11(2015) DOI: 10.13756/j.gtxyj.2015.05.003
        摘要：The Reconfigurable Optical Add/Drop Multiplexer（ROADM）is a core device for building a large-scale all-optical switching network.At present,most of the commercially available ROADMs support the colorless and directionless features;however,the unblocking feature still cannot be widely applied because of its high cost.Therefore,it is a problem at present demanding prompt solution to effectively reduce the blocking probability of the optical communication traffics.As the existing ROADM nodes have multiple add/drop port modules,this paper proposes three different Routing and Wavelength Assignment（RWA）algorithms.Simulation results show that the Plane-Wave Algorithm（PWA）with the awareness of add/drop port availability at the source and destination nodes can effectively reduce the blocking probability of the optical channel traffics as compared with those without such awareness.  
        关键词：ROADM;blocking factor;RWA;PWA   
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      • Gao Huisheng,Wang Faning
        Issue 5, Pages: 12-14(2015) DOI: 10.13756/j.gtxyj.2015.05.004
        摘要：Most of the Routing and Wavelength Assignment（RWA）problems are related to blocking rate,load balancing,signal damage and physical attacks,and rarely involved with the dependency of services on the link working state.However,link failures will surely cause the deterioration of the traffic security performances of the entire network.From the perspective of traffic risks,this article describes the impacts of link failures on the entire network services and proposes a network risk-based RWA algorithm,i.e.R-RWA.In the phase of routing assignment,this algorithm allocates the routing scheme with minor network risks to lightpath requests so as to reduce the impacts of the link failures on the entire network services.The simulation results show that compared with the classical Dijkstra + FF,this algorithm can effectively reduce the network security risks and improve the network anti-risk ability.  
        关键词：optical network;RWA;link failure;risk   
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      • Gu Jun,Guan Jianfei,Li Weiliang,Zhu Wenzhen,Luo Xiao,Ma Qun
        Issue 5, Pages: 15-18(2015) DOI: 10.13756/j.gtxyj.2015.05.005
        摘要：This paper sets up a simulation model by using the Optisystem for a DQPSK modulation-based single-fiber bidirectional WDM transmission system for performing system capacity expansion,inhibiting the effects of dispersion on the system by step dispersion compensation and reducing the FWM effects by non-uniform channel interval setting and non-uniform dispersion management.The results indicate that when the transmission distance of an 8-channel 40Gbit/s WDM transmission system is 600 km,the Qfactor of a single-fiber bidirectional transmission is improved by 14.9dB to the maximum compared with a single-fiber unidirectional transmission system.Furthermore,when the dispersion and FWM effects are inhibited,the system Qfactor can be improved by over 11 dB.  
        关键词：bidirectional transmission;step compensation;non-uniform channel interval;non-uniform dispersion management   
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      • Li Junwei,Lu Yang,Zhao Jun
        Issue 5, Pages: 19-21(2015) DOI: 10.13756/j.gtxyj.2015.05.006
        摘要：At present,the functions of Home Gateway Unite（HGU）and network positioning are oriented only to the basic requirements of the operator and adapted to the operator networks,including their business and management platforms,and all the traffic flows accessed through the home gateway are generally called data traffic.However,with the rise of smart routers and OTT services,the residential internet services and application entrance are rapidly and continuously penetrated by internet corporations and the pipeline trend of the operators is intensified.In view of the existing circumstance,this paper compares the similarities and differences between the home gateways and the smart routers in functions and positioning,analyzes the mode of their convergence and discusses the feasibility for operators to partake in entrance competitions by smart home gateways.  
        关键词：PON;home gateway;smart router   
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      • Li Haiqing,Xie Lu,Chen Gui,Li Jinyan
        Issue 5, Pages: 25-28(2015) DOI: 10.13756/j.gtxyj.2015.05.008
        摘要：Tandem pumping structure is one of the approaches to enable every single fiber of a laser to reach the maximum output power limit.This paper carries out the research work on tandem pumping-structured lasers.It first establishes a simplified model for numerical simulation,determining that the optimal pumping wavelength of such lasers should be in the range of1 0101 030 nm.Then,it develops a highly efficient 1 018 nm fiber,conducts laser performance tests and carries out comparisons,analysis and discussions.The results show that co-doping causes sub-peak of the Yb3+ionic emission blue shift,promoting the output of the 1 018 nm laser and that increasing the core/cladding ratio is conducive to improving the 1 018 nm laser output efficiency.  
        关键词：tandem pumping;1 018nm pumping wavelength;fiber laser   
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      • Lu Yunqing,Lu Yi,Wang Jin,Zhang Chi,Jiang Xinli
        Issue 5, Pages: 29-31(2015) DOI: 10.13756/j.gtxyj.2015.05.009
        摘要：In order to investigate the effects of high humidity on the dynamic fatigue of optical fibers,we select multiple groups of fibers in experiments and measure their dynamic fatigue in high humidity and normal environments by the two-point bending method.On the basis of analyzing the dynamic fatigue curves and the experimental data,we find that the fracture stress that fibers can endure is reduced in a high-humidity environment and that the higher the stress rate,the more distinct the fracture stress is decreased,thus affecting the Nd values of the fiber dynamic fatigue parameters.  
        关键词：environmental humidity;dynamic fatigue;optical fiber   
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      • Yang Zhikai,Zhou Xuejun
        Issue 5, Pages: 32-34(2015) DOI: 10.13756/j.gtxyj.2015.05.010
        摘要：This paper presents a new security precaution measure for submarine fiber cables,i.e.embedding fiber grating hydrophones in the cable to monitor anchor dragging in the vicinity of the submarine cables,analyzes the traits of the acoustic sources and builds a acoustic field model on the basis of Taiwan Strait and simulates the acoustic Transmission Loss（TL）.The simulation results show that when these hydrophones are spaced 500 mapart,this method can be used to determine the location of the acoustic sources in the scope of about 1km along the submarine cables.  
        关键词：safety monitoring;fiber grating hydrophone;acoustic field;passive sonar localization   
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      • Wei Hongyan,Tang Yongguang
        Issue 5, Pages: 35-37(2015) DOI: 10.13756/j.gtxyj.2015.05.011
        摘要：Interstitial holes are usually formed in the cladding of Photonic Crystal Fibers（PCF）in the actual drawing process.This paper presents an optical fiber in honeycomb-like lattice structure.Using the full-vector Plane Wave Expansion（PWE）method,it analyzes the bandgap properties of its circular and hexagonal cores,finds that the impacts of the core shape on the bandgap is relatively small and verifies that the Photonic Band Gap（PBG）is formed mainly due to the orderly arranged air holes in the cladding.Furthermore,it calculates and analyzes the effects of the interstitial hole diameter dint,hole pitchΛand air filling ratio fon the bandgap properties.The analog computation results indicate that in certain scope of dint,the bandgap width increases with both increasing fand reducingΛ,and the bandgap shifts towards the high frequency side.Finally,from the mode field area computation of the actually drawn fibers and the theoretical study of PBG distribution,it finds that the light in fibers in this structure mainly focuses on basemode transmission and there exist PBGs in the range of visible light waves.  
        关键词：PCF;honeycomb-like structure;bandgap;full-vector PWEM   
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      • Li Meifeng,Wang Jinghao,He Yan,Zhang Minming
        Issue 5, Pages: 38-40(2015) DOI: 10.13756/j.gtxyj.2015.05.012
        摘要：Optical Frequency Combs（OFC）generated on the basis of Four-Wave-Mixing（FWM）effects in micro-ring resonators can be used in multi-wavelength light sources and soliton transmission and storage,well satisfying the requirements of optical communication networks.Up to now,there have been large amounts of experiment reports published about such OFC,but their theoretical studies are comparatively scarce.This paper summarizes several latest theoretical analysis methods for micro-ring resonator-based OFC,including Nonlinear Coupling Mode Equation（NCME）and nonlinear Lugiato-Lefever Equation（LLE）,and makes comparative analysis of their advantages and disadvantages.The results show that nonlinear LLE is more suitable for the theoretical study of micro-ring resonator-based ultra-wideband OFC thanks to its fast computation speed.  
        关键词：micro-ring resonator;FWM;OFC;NCME;nonlinear LLE   
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      • Zhang Fengjuan,Wang Jiaxian
        Issue 5, Pages: 41-43(2015) DOI: 10.13756/j.gtxyj.2015.05.013
        摘要：With a dichroic mirror and a variable transmittance mirror as a resonant cavity,this paper realizes the continuous and Q-switching of a double-clad Tm3+-doped fiber laser pumped by a 792 nm laser diode.The experimental results show that the optimal output transmittance of the gain fiber exists when the pump power and fiber length are fixed and the laser power output is the largest.With 70% of the optimum transmittance,the obtained laser center wavelength is 1 930 nm,its output power is5.9 Wand the corresponding slope efficiency is 46%.Then it conducts the stable passive Q-switching of the fiber laser by using graphene dispersion liquid as a saturable absorber and inserting it between the gain fiber and the output mirror.When the pump power rises to 3.4 W,it obtains the maximum average output power of 39 mW with the corresponding pulse width of0.9μs,pulse repetition rate of 67 kHz and single pulse energy of 210 nJ.In addition,the average output power and pulse width are approximately linear with the incident pump power.  
        关键词：graphene;Tm3+-doped fiber;saturable absorber;passively Q-switched   
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      • Yang Likun,Chen Xiaoqiang
        Issue 5, Pages: 44-46(2015) DOI: 10.13756/j.gtxyj.2015.05.014
        摘要：The power capacity,attenuation constant and characteristic impedance of ridge waveguides are the major parts of their transmission characteristics.In their daily applications,their components are sure to subject to certain deformations.This paper calculates the impacts of displacement and stress deformation of triangular ridge waveguides on their power capacity,attenuation constants and characteristic impedance by applying ANSYS modeling in combination with MATLAB software.The results indicate that displacement deformation brings about relative minor effect on the attenuation constant,while bottom deformation produces relatively major effects on various characteristic parameters.These study results can provide some reference for the extensive applications of triangular ridge waveguides.  
        关键词：finite element method;triangular ridge waveguide;power capacity;attenuation constant;characteristic impedance   
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      • Xu Xiaofeng,Liu Yu,Jia Peipei
        Issue 5, Pages: 47-50(2015) DOI: 10.13756/j.gtxyj.2015.05.015
        摘要：In order to obtain a broadband Hybrid Fiber Amplifier（HFA）with high-gain,low noise and good gain flatness,on the basis of a theoretical model of Erbium-Doped Fiber Amplifier（EDFA）and optical Fiber Raman Amplifier（FRA）respectively,we design a EDFA+FRA HFA structure,build a HFA simulation system,optimize its performance parameters,study its gain,bandwidth,flatness and noise index.Through the complementation between EDFA and FRA gain slopes,the HFA acquires the advantages of both EDFA and FRA and compensates their respective deficiencies,which is significant to high-rate,large-capacity and wide-bandwidth long distance fiber-optic communications.  
        关键词：EDFA;FRA;HFA;gain;bandwidth;noise index   
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      • Yang Yingmao
        Issue 5, Pages: 51-54(2015) DOI: 10.13756/j.gtxyj.2015.05.016
        摘要：In order to solve the problem of Fabry-Perot Filter（FPF）distortion resulted from the insufficient driving capability in high-frequency scanning,this paper designs a push-pull driving circuit with a scanning frequency of 1kHz for a FPF-based tunable laser.It performs the modeling of the driving circuit by the TINA software,analyzes by simulation the impacts of the capacitive load of piezoelectric ceramics on this circuit and finds the method for its capacitive compensation.By using this method,it removes the hidden trouble of its self-excited oscillation,thus solving the problem of distortion generated when high-frequency signals drive a large capacitive reactance load.The test results show that with this driving circuit-based FPF,the highspeed tunable laser has good performance and its wavelength demodulation error is less than ±10pm in high frequency of1 kHz.  
        关键词：high-speed;FPF;driving-capability;capacitive compensation   
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      • Li Sai,Jiang Lin
        Issue 5, Pages: 55-58(2015) DOI: 10.13756/j.gtxyj.2015.05.017
        摘要：In view of the possible failures of the traditional asynchronous FIFO in OTN circuits,this paper proposes a kind of asynchronous FIFO suitable for OTN circuits,in which reading/writing addresses will be reset when empty/full emerges in the asynchronous FIFO,without affecting the simultaneous read/write functions of the circuits.It is easier to judge whether the asynchronous FIFO is in empty or full state by comparing the highest two read/write addresses to determine if the indicator signal close to empty or to full.The test results show that the designed FIFO empty/full resetting function is normal and the read/write rate can reach up to 133 MHz.  
        关键词：OTN;asynchronous FIFO;empty/full resetting   
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      • Yang Yingjie,Wang Xiaofeng,Qu Zhaoyang,Zhang Wenlong
        Issue 5, Pages: 59-62(2015) DOI: 10.13756/j.gtxyj.2015.05.018
        摘要：As major parts of the traditional MMSE-Rake algorithm,the optimization &selection of fork indexes are widely applied in UWB Rake receivers.In order to improve the fast recognition ability of the UWB system for multipath signal reception in low-speed transmissions,this paper proposes an improved Minimum Bit Error Rate（MBER）algorithm based on optimizing the tap coefficients and realizes fast location by simplifying the Rake fork index without reducing the multipath resolution.The simulation results show that,in low-speed CM3 and CM4multipath simulation channel transmissions,the improved algorithm is superior to the conventional MMSE-Rake algorithm in performance as it does not only reduce the complexity of Rake receivers but also improve real-time signal reception.  
        关键词：Rake receiver;multipath transmission;channel equalization;MBER;MMSE-Rake   
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      • Zhao Su,Dai Jialu,Zhu Xiaorong
        Issue 5, Pages: 63-66(2015) DOI: 10.13756/j.gtxyj.2015.05.019
        摘要：In a network virtualization environment,the pricing strategy of network operators for spectrum allocation using the static game algorithm and the spectrum allocation method of every virtual operator using the static and dynamic game algorithms are proposed on the basis of a Stackelberg game model.In addition,the Nash equilibrium point when the profit of each operator is the maximum is derived.This method can maximize the revenues of network operators and virtual network operators simultaneously.Simulation results verify the effectiveness of the algorithm and the existence of Nash equilibrium point.  
        关键词：Stackelberg game;resource allocation;Nash equilibrium;network virtualization   
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      • Liu Bintao,Zhang Xingxing,Nie Wenxia
        Issue 5, Pages: 67-70(2015) DOI: 10.13756/j.gtxyj.2015.05.020
        摘要：In order to develop the testing instruments for TD-LTE systems,it is necessary to test and verify the functions of every layer and the main objective of the Radio Link Control（RLC）layer is to perform the data processing function.On the basis of careful research and analysis of the 3GPP development and testing protocol,this paper first compiles and writes the test cases in software CCS for simulation so as to verify the conformance of the RLC protocol.Then,it builds the TTCN-3platform and verifies the functions of the RLC lay by system-level tests.The verification results prove that all the functions of this layer are correctly implemented on these two platforms,which lays a sound foundation for the development of these test instruments.  
        关键词：TD-LTE;RLC;data processing;testing   
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      • Zhang Demin,Zhang Youyuan,Wu Zhonghua,Xu Xiaohan
        Issue 5, Pages: 71-74(2015) DOI: 10.13756/j.gtxyj.2015.05.021
        摘要：With the gradual commercialization of the 4Gtechnology,we will surely see the simultaneous existence of 4G,3Gand2 Gfor a long period of time,therefore Inter-RAT system interoperability is particularly important.In view of such a perspective,this article designs a set of TTCN-3-based test scheme for TD-LTE system and GSM system and verifies it by Inter-RAT system switching.By building a new simulation platform to generate the test flow charts and test reports and analyzing the test results,it verifies the superiorities of the test platform and the rationality and feasibility of this test scheme.  
        关键词：TTCN-3;Inter-RAT system;handover;TD-LTE;GSM;interoperability   
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      • Li Xiaowen,Zhou Yao,Zhang Aiping,Feng Youbo
        Issue 5, Pages: 75-78(2015) DOI: 10.13756/j.gtxyj.2015.05.022
        摘要：In LTE-Advanced（LTE-A）uplinks,a non-contiguous frequency resource allocation based on clustered DFT-SOFDM is supported.In order to implement such resource allocation in PUSCH,solving the combinatorial index becomes a critical issue.With regard to this issue,this paper presents a combinatorial system-based greedy algorithm,which uses table checkup instead of the conventional full-search algorithm,reducing the number of searching times fromO（N4）to O（N）.This algorithm is realized in DSP,verifying its greater feasibility and effectiveness.  
        关键词：LTE-A;PUSCH;resource allocation;combinatorial index;DSP realization   
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