最新刊期
卷 ， 期 4 ， 2012
- 摘要：As the quality of the modulated optical signals is associated with that of the transmitted and received signals,it is very important to test and analyze them.This paper describes the generating principle of the modulated optical signals in 100 Gbit/s transponder modules and conducts the necessary theoretical exploration of such parameters as Optical Signal Noise Ratio（OSNR）,Error Vector Magnitude（EVM） and constellation map involved in digital optical signal tests.In addition,it analyzes the graphs of constellation maps of various QPSK signals,offering an effective reference for the analysis by transmitters.关键词：DP-QPSK transmitter;QPSK modulated signal;OSNR;EVM;constellation map
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发布时间： - 摘要：Quantitative analysis of the impacts of phase noise and shot noise on Phase-Locked Loop（PLL） performances in PSK heterodyne optical communication systems is made in detail.The relationship between PLL optimal bandwidth and laser linewidth and the requirements of bit error rate and bit rate on laser linewidth are obtained.These results are instructive to the design optical PLL.关键词：coherent detection;phase noise;shot noise;optical PLL
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- 160
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发布时间： - 摘要：In this paper,we analyze the correlation characteristics of Rayleigh backscattering signals of incident light with different frequencies in the frequency domain on the basis of the distributed fiber temperature and the strain sensing principle of the Coherent Optical Time-Domain Reflectometer（COTDR）.Then,we explain the transmission principle of the Rayleigh backscattering signals in sensing fibers with a discrete Rayleigh backscattering model,simulate and analyze the COTDR process and analyze the power and correlation characteristics of incident signals with different pulse widths by using MATLAB software.The results show that the input pulse width is inversely proportional to the correlation width in frequency domain,i.e.the precision of the sensing position is inversely proportional to temperature or strain precision.关键词：distributed optical fiber sensing;COTDR;Rayleigh backscattering
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发布时间： - 摘要：The ITU-T G.8032 protocol only defines the automatic protection scheme for Ethernet ring networks when a single link fails,but not when multistage links fail.This paper expounds the working principle of the single ring and multiple rings in the ITU-T G.8032 and analyzes the problems and defects in multiple rings.On this basis,it presents a multistage protection switching mechanism for multiple rings.Using the concept of virtual links in multiple rings,it focuses on the research on the failure detection and the virtual link protection,thus realizing the protection of the multi-stage rings in Ethernet ring networks.The test results show that the multistage protection switching can be accomplished within 50 ms,satisfying the self-healing time requirement of the carrier-class Ethernet networks and improving their reliability.关键词：ITU-T G.8032;Ethernet ring network;multistage protection switching;virtual link
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发布时间： - 摘要：The novel phase modulation format technology is important to optical transmission systems as it can effectively reduce the damages in optical transmissions.This paper theoretically analyzes the principles of modulation and demodulation of optical M-ary Differential Phase Shift Keying（MDPSK）,establishes its common modem structure and derives for the first time its general and demodulation formulas.Finally,it obtains by using MATLAB software the spectrum after modulation and eye diagram after demodulation,taking DQPSK,8DPSK and 16DPSK that are based on Carrier-Suppressed Return-to-Zero（CSRZ with duty cycle of 67%） as the examples.The simulation results show that the spectral width of MDPSK modulation format gradually becomes narrower with the increase of M,and the eye diagrams is also satisfactory.关键词：fiber-optic communication;phase modulation format;MDPSK;CSRZ
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- 105
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发布时间： - 摘要：EPON-EOC-based access technology is a mainstream proposal for Triple-play of China’s Next Generation Broadcasting Network（NGB）.This paper makes an in-depth analysis of its network architecture and presents the demand features of the NGB billing system and designs on this basis a technical solution to its optimization.This solution is verified in experiments to be feasible and effective,offering a valuable reference for the further development of NGB Triple-play.关键词：NGB;EPON;EOC;billing;optimization
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发布时间： - 摘要：This paper proposes an Φ-OTDR-based distributed fiber-optic sensing system,which can easily locate intrusion,introduces its working principle and discusses the design of its software and hardware.The experimental results indicate that this system can conduct automatic identification prewarning for intrusions into different locations of communication cables and display the positions of hazards with the measuring distance of over 60 km and the orienting accuracy of 10 m.关键词：distributed fiber-optic sensing system;Φ-OTDR;perimeter protection
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发布时间： - 摘要：As the lack of intra-domain ping-pong handoff mechanism in the existing predictive FMIPv6 may lead to mass costs for remote registration and system communications,this paper proposes an FHMIPv6-based ping-pong handoff optimization scheme,in which HMIPv6 is introduced into FMIPv6.Analytical results indicate that,compared with FHMIPv6,the proposed scheme in the ping-pong handoff mode can effectively reduce time delay and packet loss and further improve throughput.关键词：mobile IPv6;FMIPv6;FHMIPv6;ping-pong handoff;fast handover;tunneling
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- 48
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发布时间： - 摘要：In view of the disadvantages of the cross product frequency discrimination method for FM signal digital demodulation,such as excessive occupation of hardware resource,low accuracy and limited application to narrowband signal demodulation only,this paper adopts an improved algorithm,which avoids computing the approximate the inverse tangent value and reduce to the maximum the algorithm complexity by changing the processing of the signals in I and Q channels,thus realizing the demodulation with less occupation of resource,higher accuracy and suitability for both narrowband and broadband FM signals.Simulation by Matlab and implementation on the platform of Quartus II 11.0 software based on the Cyclone III chips verify the feasibility of this algorithm.关键词：digital demodulation;polyphase filter;orthogonal transformation;FPGA
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- 234
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发布时间： - 摘要：GPON has become the mainstream technology for present broadband access networks because of its high efficiency,large bandwidth,ability to offer all services and other advantage and WLAN technology provides the users with convenient and fast multi-service radio broadband services.On the basis of the characteristics of GPON and WLAN and different covering scenarios of WLAN,this paper studies the WLAN over GPON-based networking scheme,providing a valuable reference for network planning.关键词：GPON;WLAN;networking
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- 55
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发布时间： - 摘要：Using the Photonic-Bandgap effect,this paper designs a hollow-core Bragg fiber with its center wavelength of the transmission waveband at 10.6 μm with the semiconductor glass and organic polymer as the cladding material and analyzes the effects of the number of the radial cladding on the transmission loss of the fundamental mode HE11 by using COMSOL Multiphysics simulation tool,the results show that when the number increases to 20,the loss value falls to 0.051 4 dB/m,obviously better than 0.6 dB/m,the lowest value the ordinary sulfur compound fibers can reach.This kind of Bragg fiber can be applied to both medical high power CO2 laser transmission and long-distance infrared transmission.关键词：Bragg fiber;CO2 laser;infrared waveband;transmission loss
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- 130
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发布时间： - 摘要：Fiber excess length is an important performance index in submarine optical cable communications.At present,we have no experimentation for the accurate analysis of submarine cable fiber excess length distribution but the analytical method.This paper presents two experimentations for the accurate analysis of the fiber excess length in the stainless central-tube,high-energy ray method and the fiber grating method,and theoretically analyzes their feasibilities.关键词：submarine optical cable;fiber excess length;high-energy ray;three-core fiber Bragg grating
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发布时间： - 摘要：To improve the detection efficiency of optical submarine cables and overcome the shortcomings of active magnetic detection,this paper first presents a passive magnetic detection,i.e.magnetic anomaly detection,on the basis of their armoring,then it conducts an in-depth analysis of its principle and carries out theoretical derivation by using the models of infinite long cylinder and magnetic dipole field,which are instructive to the simulation and experiments in the future.关键词：optical submarine cable;passive magnetic detection;magnetic anomaly detection
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- 249
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发布时间： - 摘要：THz wave modulator is one of the key devices in THz wave communication systems.This paper proposes a novel dual-wavelength THz wave modulator based on the direct coupling of compound lattice photonic crystal.This modulator can realize the optical-control modulation of dual-wavelength THz waves via one point defect by introducing nonlinear material GaAs into only one point defect.The numerical simulation results show that for two different incident THz waves,this modulator has low insertion loss,high extinction ratio and high modulation rate.Compared with similar side-coupled modulators,the proposed modulator has higher extinction ratio.关键词：compound lattice;photonic crystal;direct coupling;dual-wavelength;THz wave;Modulator
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发布时间： - 摘要：This paper analyzes the defects of the conventional systems of two-output optical distributors and gives the ideas and solutions.Specifically,it presents a new specification system and elaborates on its establishing method and design process.In this system,the application scopes between adjacent specifications are neither overlapped nor broken and the variations of the optical node levels of every specification always remain within the same allowable scope in different application scopes.The specifications are not chosen by calculating the splitting ratio that the network needs,but by the specification table directly according to the two-output fiber length differences.Therefore,it is very simple and convenient for the designers to use this system.关键词：two-output optical distributor;optical splitting ratio;optical fiber length difference;specification value;application scope;bandwidth
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发布时间： - 摘要：This paper presents a 40 Gbit/s CFP optical module used in the Metropolitan Area Network（MAN）.Consisting of receiving unit,transmitting unit and control unit,this module realizes the transmission of four lines of 10 Gbit/s carrier signals with different wavelengths in a single fiber by using the WDM technology.Then it describes the working principles of the above three parts and their specific design schemes and conducts the relevant tests on the prototype by IEEE 802.3ba standard.The results show that this module fully satisfies the application requirements of 40 Gbit/s Ethernet.关键词：IEEE 802.3ba standard;CWDM;transmitting unit;receiving unit;control unit
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发布时间： - 摘要：In view of the possible deformations of ridge waveguide devices in production,assembly and use,this paper studies the effects of displacement distortion and distortion under stress on the attenuation characteristics,power-handing capability and impedance characteristics of rectangular single ridge waveguides by using the finite element method.Numerical analysis results indicate that with the increase of deformations,the attenuation constant increases and the power-handing capacity and impedance decrease.But lateral deformation affects the characteristic parameters the most,so it should avoided as much as possible in the use of waveguide devices.关键词：finite element method;ridge waveguide;attenuation constant;power-handing capability;impedance characteristic
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发布时间： - 摘要：Scheduling is an important link and key technology for resource assignment by basic stations to users in Long Term Evolution（LTE） systems.The User Equipment（UE） usually obtains radio resource by delivering Buffer Status Report（BSR） and Schedule Request（SR）.As the simultaneous existence of BSR and SR results in the waste of the resources,this paper designs a solution on the basis of different parameters and presents an approach for triggering BSR and SR in Semi-Persistent Scheduling（SPS） and removing the conflicts between the padding BSR and other BSRs,effectively improving the resource utilization efficiency and system stability.关键词：LTE;schedule;schedule request;BSR
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- 135
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发布时间： - 摘要：The encoding/decoding of Radio Resource Control（RRC） messages is one of the key steps of LTE protocol stack software.On the basis of the Abstract syntax and transmission syntax in LTE protocol messages,a new solution scheme for Abstract Syntax Notation（ASN） module is designed.Adopting the idea of structured programming,this module is so structured that its content is more limpid and easier to be expanded.The module can realize the correct encoding/decoding of RRC messages in the conformance tests by the ASN.1 Tools of OSS Nokalva,and fully satisfies the requirements of the protocol stack software.关键词：RRC;ASN;UPER;encoding/decoding
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发布时间： - 摘要：In view of the relative motion deviation arising from the initial acquisition in satellite laser communications,we establish a relative motion compensation model for intersatellite laser communications.If only we provide a little star calendar table enquiry,this model can acquire high precision compensation data.Stimulant results show that this model can reduce the deviation resulting from uncertain region scanning,enabling high-probability and fast establishment of laser communication links in intersatellite laser communications.关键词：intersatellite laser communication;initial acquisition;deviation;scanning compensation
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发布时间： - 摘要：In response to the demand for Unmanned Aerial Vehicle（UAV） networking communications,we obtain the advantages of diversity gain and communication quality improvement by using the Multi-input Multi-output（MIMO） technology.We construct a model for UAV cooperative communication system and present a cluster algorithm for MIMO collaborative transmissions.Then we conduct theoretical analysis of the Signal to Interference and Noise Ratio（SINR） in the course of communication and come to know that it can effectively improve the SINR in collaborative transmissions as compared with single node transmissions.Finally,we verify the correctness of the analysis by simulation in the model and simultaneously simulate the synchronization technology embedded in the cluster algorithm,effectively solving the problem of Inter-Symbol Interference（ISI）.关键词：cooperative MIMO;cluster recruiting;SINR;ISI
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