最新刊期
卷 ， 期 5 ， 2010
- 摘要：With the rapidly increasing demands for access network bandwidth and service support,ring PON applications have become increasingly more important and still longer transmission range,supporting more ONU and seamless conversion with ring networks have become the prerequisites for the continued development of PON in MAN.This paper elaborates on the principle and key technologies of the ring-tree topology-based PON,discusses the typical applications of such an architecture and summarizes the advantages and disadvantages of different schemes,providing references for the study on the still deeper conversion of access networks with MAN.关键词：ring architecture;ring-tree hybrid architecture;MAN;WDM-PON
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- 80
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发布时间： - 摘要：Along with the large-scale applications of NGN and 3G networks,the traditional PSTN mainly based on circuit switching gradually turns to PTN mainly based on packet-switching.However,in the conversion from the traditional networks to the future networks,clock synchronization remains to be one of the big problems.This paper analyzes two technologies for time synchronization in PTN,Ethernet synchronization technology and IEEE 1588 V2 protocol,and describes their principles and applications in PTN clock synchronization.关键词：PTN;Ethernet;clock synchronization
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- 171
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发布时间： - 摘要：We propose and demonstrate a novel architecture for the SSB-ADM-based OFDM-PON system.Its downlink transmission is based on 10 Gbit/s SSB-based OFDM-4-QAM modulation,while the uplink transmission is based on 2.5 Gbit/s ASK modulation in the Time Division Multiple Access（TDMA） mode by using the other sideband retained in the downlink signals.This architecture can perfectly overcome the Rayleigh backscattering effect in the bidirectional transmission.When the backscattering effect is considered,the power penalty will be <0.8 dB for downlink signals and <1.8 dB for uplink signals.关键词：OFDM;PON;SSB
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- 226
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发布时间： - 摘要：At present,improving transmission rate and spectral density has become a hotspot in optical communication research.To use advanced modulation formats is the key for achieving these two aims and quadrature modulation format is one of them.This article presents a study method for calculating the BER of multi-dimensional and multi-level quadrature modulation signals and derives for the first time the analytical expression for multi-level phase-modulated signals and the simulation results by this method.In addition,it discusses the effects of such parameters as extinction ratio on BER.关键词：quadrature modulation;BER;linewidth;extinction ratio
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- 97
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发布时间： - 摘要：On the basis of the widely used SDH-based MSTP,the DWDM-based OTN is introduced.In the access layer,MSTP is used for service delivery and ring net protection,while in the convergence or even backbone layer,OTN is used for the transfer of large granular services.In this design,two entirely different transfer network mechanisms are integrated to create conditions for mobile telecom carriers to fast realize large flow and bandwidth services on the basis of MSTP networks.关键词：MSTP;OTN;hybrid networking;private line
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- 122
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发布时间： - 摘要：With the development of campus networks,there have been more and more application systems on the campus networks and these system authentications are independent to each other,not adapted to the development of the digitalized campus networks.On the basis of the analysis of the conventional authentication schemes and the minimum changes of the existing systems,this paper proposes a security single-point login scheme and realizes the unified digitalized security identity authentication based on campus networks by using PKI,LDAP,CAS.关键词：LDAP;authentication;SSO;PKI
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- 123
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发布时间： - 摘要：In this paper,qualitative and quantitative analyses of the network security are made by using the Analytic Hierarchy Process（AHP）,the assessment system is established and the calculation and analysis by AHP is completed by using the analysis software Expert Choice,so as to facilitate a comprehensive assessment of the network security,analyze various security hazards and enhance network security management.关键词：AHP;optical transmission network;security assessment
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- 55
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发布时间： - 摘要：In connection with the engineering applications of RFC 2544 standard,we put forward an overall scheme for RFC 2544-based Ethernet performance test software,which runs on the Windows CE System platform.Then we discuss in detail the implementation of several key function modules,including Ethernet II packet construction,software and hardware interaction,data management and graphic operation.The test results indicate that this software runs reliably and functions correctly on the hardware platform and its code is highly robust,effective and scalable.关键词：RFC 2544 standard;Ethernet II frame;information interactive;data management
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- 174
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发布时间： - 摘要：This paper describes and analyzed the Warning,Protection,Detection,Response,Recovery and Counterattack（WPDRRC） information security model systematically,conducts a theoretical analysis of this model and compares it with other similar models in safety and protection functions.Finally,it illustrates its applications of in multi-level security protection.关键词：WPDRRC;information security model;multi-level security protection
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- 233
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发布时间： - 摘要：The ultraviolet transmission properties of quartz optical fiber are studied and analyzed,and a design for the quartz ultraviolet transmission fiber prepared by the PCVD process is presented.On the basis of the property tests and analysis of the results,the effects of the components of the doped material on the quartz fiber transmission properties are summarized,providing useful basis for developing high-performance quartz ultraviolet transmission fibers.关键词：quartz optical fiber;ultraviolet transmission;PVCD
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- 192
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发布时间： - 摘要：With the explosive growth of the data communications volume and the urgent demand for the increase of fiber-optic communication system capacity,S-band（1 470～1 539 nm） development has become an important approach for the system capacity expansion.The Er-doped fiber-based development of S-band optical amplifiers is an optimized scheme for developing S-band active devices and realizing communication system capacity expansion.This paper mainly introduces the various implementation schemes for the said amplifier（S-EDFA） and the latest research advances,describes and analyzes S-EDFA experimental set-ups in different configurations,work principle and performance indexes.关键词：EDFA;W-type Er-doped fiber;S-band
- 3
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- 198
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- 0
发布时间： - 摘要：The network topology,band allocation and power budget for 10 G-EPON are first introduced in this paper.And then,taking BOSA in ONU of asymmetric 10 G-EPON as an example,the key technologies for the development of the device is briefly discussed.Finally,comprehensive tests are conducted on the prototype and the results are analyzed.关键词：10 G-EPON;BOSA;ONU
- 3
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- 111
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- 1
发布时间： - 摘要：As one of the key devices of optical communication systems,the high-rate SFP optical module is always the research focus in the field of optical communication.Among others,to maintain a stable extinction ratio is a highly important performance of high-rate SFP optical modules.This paper describes several commonly used schemes,in which the extinction ratio is kept stable by adjusting the modulating current by temperature compensation and introduces their characteristics and basic principles.These analyses and studies are of high reference values for the design of SFP optical modules.关键词：SFP optical modules;extinction ration;temperature compensation;optical power
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- 229
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发布时间： - 摘要：This paper studies the optimization of the transmission performances of a XFP module by using an Electronic Dispersion Compensation（EDC） equalizer.A test platform is set up as required in tests,on which 80km EML light source is used as the optical transmitting part,an APD+TIA photoelectronic detector as the receiving part and the EDC equalizer performs the dispersion compensation algorithm for the code stream from the photoelectronic detector to optimize the line characteristics.When the light source is directed into the equalizer,the transmission range is extended to 120 km.关键词：optical communication;EDC;XFP module
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- 73
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发布时间： - 摘要：In this paper,a double-clad fiber-optic microbend sensor and its dark-field detection method are presented.The theoretical model for the double-clad fiber bending loss is established by theoretical analysis and simulation.The optimum structural parameters are obtained by the simulation of the relationship between the fiber structural parameters and sensing sensitivity,the optimum period,tooth spacing and tooth number of the deformer are analyzed in theory and simulation and the double-clad fiber microbend sensor and its dark-field detection method are experimentally studied.The results show that there is a good linear relationship between the sensor output light field and fiber deformation.关键词：sensor;fiber-optic microbend sensor;double-clad fiber;dark-field detection
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- 105
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发布时间： - 摘要：In this paper,we propose a novel sensor structure that can improve the signal-to-noise ratio of Brillouin Optical Time Domain Reflectometer（BOTDR） by using a nonlinear reflector,which is constructed by a 3 dB coupler with two sensing fibers of the same type placed in the same temperature or strain circumstance.Due to the constructive inference of the nonlinear reflector,the output signal intensity of the sensing system is raised four times that when only one sensing fiber is used,improving both the system SNR and measurement accuracy but also the system reliability.关键词：nonlinear reflector;BOTDR;intensity measurement;frequency shift measurement;reliability
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- 146
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- 1
发布时间： - 摘要：This paper introduces the research status and the basic principle of the Iu standard interface optical signal acquisition card for TD-SCDMA networks.On the basis of the comparison with the traditional acquisition cards,a design scheme for the improved acquisition card is presented and brief analysis and introduction of the components of its hardware system made.Finally,the basic principle of the hardware debugging is summed up.关键词：TD-SCDMA;Iu standard interface;optical signal acquisition card;ATM
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- 27
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发布时间： - 摘要：In connection with the effects and requirements of backoff strategy in the Medium Access Control（MAC） protocols,the backoff strategy for a typical MAC protocol for wireless sensor networks,S-MAC protocol,is analyzed,the network collision probability adaptive backoff strategy presented and performance simulation tests conducted by using NS2.The results indicate that in the network environment where the network nodes are densely distributed and the burst data flow varies greatly,the energy efficiency and throughput of the new scheme are both much improved.关键词：collision probability;adaptive;backoff strategy;simulation
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- 160
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- 7
发布时间： - 摘要：This paper presents a design method of transmission precoding in the PUSCH of the 3GPP LTE System,which is a FPGA-based DFT/IDFT processor.This processor can be dynamically configured according to different input data length,the hardware resources are shared and the processing speed and data accuracy meet the LTE system test requirements.This processor module is verified in Verilog HDL on Virtex 5 FPGA of Xilinx and is optimized.关键词：PUSCH;DFT/IDFT;FPGA
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发布时间： - 摘要：In the 3rd Generation Partnership Project（3GPP） Long Term Evolution（LTE） system,synchronization signals include primary and secondary synchronization signals,used for cell search.This paper describes the generation process the secondary synchronous signals and presents a simple implementation scheme in accordance with the features of fixed-point Digital Signal Processing（DSP） and have it verified by MATLAB.This scheme has been applied in the development of the LTE-Time Division Duplex（TDD） wireless integrated test instrumentation.关键词：LTE;secondary synchronization signal;primary synchronization signal;DSP
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- 160
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发布时间： - 摘要：In this paper,the authentication in the LTE non-access-stratum and the establishment and use of the security context of an Evolved Packet System（EPS） are studied and an improvement scheme presented.In this scheme,the system signalling overhead is decreased and the time-delay processing reduced.By comparing the new scheme with the conventional one in implementation efficiency,the times of communication and time delay in these two schemes are analyzed,indicating that the new one is better in terms of link resource saving and processing time reduction.关键词：authentication;SMC;EPS security context;signalling overhead
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发布时间： -
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