最新刊期
卷 ， 期 1 ， 2013
- 摘要：In this paper,a 16×40 Gbit/s DWDM systems with a long haul（500-2 000 km） is studied and the effects of different modulation modes（Carrier-Suppressed Return-to-Zero（CSRZ）,Duobinary Return-to-Zero（DRZ） and Modified Duobinary Return-to-Zero（MDRZ）） and dispersion compensation（pre-,post-and intermediate） schemes on its transmission performances analyzed.Simulation results show that when the transmission distance is beyond 1 500 km,the Four-Wave Mixing（FWM） effects are well suppresses in the MDRZ mode so that its performances are improved,and better compensation results are achieved when the intermediate dispersion compensation scheme is adopted than the other two.关键词：DWDM;CSRZ;DRZ;MDRZ
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发布时间： - 摘要：In Virtual Private Networks（VPN）,security is a performance that the users are most concerned about.This paper analyzes the security guarantee mechanism for Multi-Protocol Label Switching（MPLS） VPN and the possible security risks that the core networks may encounter.On this basis,it proposes an improved program and verifies it in experiments.In the core networks,Message-Digest algorithm 5（MD5） is adopted among Border Gateway Protocol（BGP） neighbors and the Generalized TTL Security Mechanism（GTSM） for the Label Distribution Protocol（LDP） neighbors.Taking security and complexity both into consideration,this program is proved to be effective in enhancing the security of MPLS VPN core networks.关键词：MPLS VPN;security;MD5;GTSM
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发布时间： - 摘要：In view of the limitations of the electric signal processing-based stream cipher encryption/decryption technology for optical communication security systems,this paper presents an all-optical signal processing-based encryption/decryption technology,studies several typical all-optical XOR encryption schemes and introduces their operating principles,characteristics and research advances.Then,it builds a simulation model for the SOA-MZI XOR gate-based all-optical encryption/decryption system using the OptiSystem software and optimizes the system by a optimization structure designed on the basis of the self-phase modulation effects of High Nonlinear Fiber（HNLF）.Studies show that the all-optical encryption/decryption technology has excellent performances and enables the entire security system to have higher operation rates and more secured transmissions.关键词：all-optical encryption/decryption;communication security system;XOR gate;SOA;HNLF
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发布时间： - 摘要：Symbol synchronization offset seriously affects the performances of OFDM systems.In view of the existence of metric plateau when the S&C method is used and of redundant peaks when the Minn method is used,a new symbol synchronization method is proposed in this paper.This new timing metric calculation method is designed on the basis of the Minn method,which eliminates the timing metric plateau and avoids that of redundant peaks in the timing metric curve.Simulation results show that when this method is used,the timing metric curve has only one peak and has even smaller Mean Square Error（MSE） in low SNR and multi-path fading environment.关键词：OFDM;symbol synchronization;training sequence;multi-path fading;MSE
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发布时间： - 摘要：In view of the deficiency of the conventional logging transmission systems,a fiber-optic transmission scheme for high-temperature logging information is designed.In the design,a low-power MCU of TI MSP series is employed as the processing chip of the down-hole monitoring system,high-temperature optical modules as the signal receiver and high temperature resistant optical fiber as the transmission media.The host computer can not only send commands to control down-hole drillers and sensors,but also display the logging information,e.g.temperature,pressure,resistance,etc.Experimental results show that this scheme can implement prolonged long-range broadband（up to 2 Mbit/s） transmission of logging information in high-temperature environment（110℃） and offer flexible way of expansion for the system so that it occupies still less room and becomes lighter.关键词：fiber-optic transmission scheme;oilfield logging;high temperature environment;MCU
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发布时间： - 摘要：On the basis of an optical network geographical distribution model,we conduct modeling for and simulation of a network topographical structure by adopting the WCGM algorithm and find out the aggregation of worst circular cut of the network.Furthermore,we compute the network node risk probability and assess the vulnerability of the network on the basis of the node risk probability.This work is useful for improving the survivability of optical networks.关键词：network geographical distribution;NWCC;node risk probability;optical network
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发布时间： - 摘要：In order to analyze the flat dispersion properties of microstructure fibers,a microstructure fiber with a circular arrangement is designed,the cladding of which consists of periodically distributed air holes.Its dispersion property is numerically simulated by using the finite element numerical analysis method and the dependence of dispersion on the size of the circular holes of the core and wavelength is investigated.The results show that the spaces between the inner and outer air holes and diameter both affect the dispersion curve,but the space between the big holes in the inner cladding and the diameter of the first circle of small air holes play a decisive role in the curve trend.When the diameter of the inner air holes is 3.1 μm and those of the others 10 μm,and the space from center to center of the inner air holes is 5 μm and those of the others 4 μm,the dispersion is 19.5 ps/（nm·km） at the wavelength of 1.3 μm and 26.5 ps/（nm·km） at the wavelength of 1.6 μm,and the dispersion varies in the range of 7 ps/（nm·km） in the wavelength range of 1.3-1.6 μm.关键词：microstructure fiber;finite element method;dispersion
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发布时间： - 摘要：In order to improve the output of the optical flat-top extent and expand the channel bandwidth of interleaver filters,an all-fiber cascaded Mach-Zehnder Interferometer（MZI）-typed interleaver filter consisting of one 3×3 and two 2×2 single-mode fiber couplers is developed.The expression between the output spectrum of the model and its relevant parameters is deduced using the transfer matrix method and its characteristics are analyzed.The result shows that an ideal interleaving spectrum can be produced when the difference between the coupler splitting ratio and the fiber interference arms are constant.This filter has a channel interval of 2 nm and,when assisted by double-ring fibers,its output waveform is still more flat-topped and the side-mode suppression ratio is close to the theoretical value.关键词：MZI;double-ring assisted optical fiber;coupler;wavelength interleaver filter
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发布时间： - 摘要：In order to optimize the entire performances of Microwave Photonic Filters（MPF） and their polarization stability,a Faraday spinning mirror-based MPF structure is presented.This tunable bandpass filter has high Q value,high side frequency selection and high stopband suppression ratio.On the basis of the theory of MPF,the microwave modulated signal flow of Faraday spinning mirror assisted Fiber Ring Delay Line（FRDL） is analyzed and the transfer function and the expression of Q value derived by using the signal flow graph.Finally,simulation is conducted and the effects of coupling coefficient,EDFA gain and fiber ring length on the output spectral characteristics analyzed.关键词：MPF;FRDL;signal flow graph;Faraday spinning mirror
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发布时间： - 摘要：This paper mainly introduces the composition and key technologies of the 40 Gbit/s RZ-DQPSK transponder module and presents a rational experimental scheme for the control of its transmitter and receiver ends.In addition,it tests and verifies the design scheme by using eye diagram,constellation and OSNR,which shows that the signal has an excellent eye diagram and the OSNR is 12.3 dB.The results indicate that the optical module designed in this scheme satisfies the relevant international standards,applicable in the field of optical communications.关键词：transponder module;transmitter end control;receiver end control;constellation test
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发布时间： - 摘要：This paper introduces the design scheme and key technologies for Optical Line Terminal（OLT） modules in 10 Gbit/s Ethernet Passive Optical Network（EPON） systems and focuses on describing the implementation of dual-rate burst reception at the receiving end and the composition of the hardware circuits of 10 Gbit/s burst receiving part.The test results indicate that both the reception setup time and sensitivity of this module in burst reception condition satisfy the requirements of IEEE Std.802.3av for 10 Gbit/s EPON.关键词：OLT optical module;symmetric;burst receiving;reception setup time
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发布时间： - 摘要：Emitting laser light at around 1.54 μm,the solid-state Er3+:Yb3+ codoped phosphate glass laser is widely applied in optical communications,radar and eye-safe laser range finding.In this paper,the flat-flat cavity-and flat-concave cavity-systems lasing at TEM00 1.54 μm wavelength are realized by using output wavelength of 975 nm for the LD pump sources and using Er3+,Yb3+ codoped phosphate glass.Experimental results indicate that with the increase of the resonant cavity length,the system output energy decreases,while the pump threshold power increases.In addition,the quality of the laser beam is improved by using a curve-type mirror,obtaining the output of signal light with the maximum power of 30 mW.关键词：laser;erbium glass;1.54 μm laser
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发布时间： - 摘要：On the basis of analyzing the sensing principle of differential pressure Fiber Bragg Grating（FBG） sensors,its static differential pressure sensing properties are investigated by using a hydraulic tester and a Q8384 spectrometer and the errors of the experimental results analyzed.The results indicate that the FBG sensibility coefficient is 3 pm/kPa in the pressure range of 0-0.35 MPa and the FBG wavelength varies linearly with the differential pressure with little hysteresis effect,proving that this sensor can be used in hydraulic systems for flow measurement.关键词：FBG;differential pressure sensor;sensing properties;error analysis
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发布时间： - 摘要：For the practical applications of the OFDM technology in broadband wireless communications,an OFDM transmitter design scheme based on IEEE 802.11a protocol and the implementation of its key technologies are proposed.In the design,the top-down design idea is adopted and by using the digital Phase Locked Loop（PLL） and ping-pong RAM,the system operational reliability is improved.Finally,by using the characteristics of Altera Cyclone IV E series FPGA devices and flexible IP Core functions,the transmitter OFDM design is implemented.Simulation results in the Modelsim environment indicate that this design is effective and occupies less resource.关键词：OFDM;PLL;IP Core
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发布时间： - 摘要：For the Radio Resource Management（RRM） and optimization of LTE-A systems,this paper proposes an RRM function game-based radio resource allocation strategy.In accordance with the cooperating and competitive relationship between the two functions of RRM,i.e.radio admission control and radio bearer control,it establishes a game model.By achieving the Nash balanced of the game model,it maximizes of the system service amount so as to achieve an effective unity of the economic interests of operators and the user satisfaction.关键词：LTE-A;RRM;game theory;radio admission control;radio bearer control
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- 148
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发布时间： - 摘要：In view of node random movement and limited battery energy,decreasing energy penalty to prolong the network lifetime and ensure node security are the main issues in the research on multipath routing in Ad Hoc networks.This paper analyzes the basic features of AODV and AOMDV protocols and proposes a novel secure multipath routing protocol,i.e.Energy Entropy-Based Secure Multipath Routing Protocol（EEBSMRP） in connection with netgrid and energy-entropy.Simulation results show that EEBSMRP achieves much advance in finding the routing with the minimum node energy penalty,balancing the node energy utilization rate,prolonging the network life time and improving its security.关键词：multipath routing;security protocol;energy entropy
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发布时间： - 摘要：In order to overcome the influence of dispersion in long-range fiber-optic transmission systems,we study a simplex Radio-Over-Fiber（ROF） system based on optical carrier suppression and propose an improved duplex ROF system transmission scheme,in which the down-link signals are coupled to the optical carrier suppression band using 20 GHz RF signals at the central station and then transmitted to the base stations over a 50 km single-mode fiber,while the unmodulated sideband is reused to transmit the uplink signals.The system spectrum diagram and BER curve generated in simulation show that when transmitted by coupling with uplink signals,the energy penalty of downlink signal is decreased and both the uplink and downlink become more dispersion resistant.关键词：optical communication;ROF system;duplex system;optical carrier suppression
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发布时间： - 摘要：In view of the difficulties of black box or other missile-borne recording equipment in searches,this paper proposes a BPSK modulation-based design for radio beacon machines.This design selects u-blox GPS NEO-5Q module for self positioning and DDS chip AD9910 for HF BPSK modulation and then emits the beacon data frame at a certain frequency band via an RF circuit board.Actual measurement shows that this design can obtain BPSK modulated signals with the output power of up to 1.9 mW at over 400 MHz.Using the idea of software radio,this design implement various function of radio stations by software and has features of flexibility and openness.关键词：BPSK;GPS;radio beacon
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发布时间： - 摘要：In order to solve the problems in multi-user terminal access and tests of wireless Access Controller（AC） performances when dealing with large numbers of users in its development and tests,this paper mainly introduces the design principle of a STA simulator that supports Extensible Authentication Protocol-Subscriber Identity Module（EAP-SIM） authentication,In line with EAP-SIM protocol,this simulator simulates the access and authentication flow of real SIM card users,implements the access and authentication of large numbers of users,and performs pressure and performance tests on the AC.关键词：station simulator;wireless AC;EAP;SIM
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发布时间： - 摘要：In order to improve the processing capacity of single boards in network Access Controllers（AC） for accommodating the constantly growing number of users and daily increasing amount of network data,this paper adopts a multi-board communication strategy,introduces its basic principle and analyzes in-depth the key factors affecting its performances.Furthermore it proposes a method appropriate for multi-board communication and the programming.By the dynamic regulation of the AC to associate the modules in every board,it operates the traffics in the corresponding board so as to ensure the load balance of every data flow.Taking into account the performances and operation of all the boards,it improves the overall performances of the AC system and reduces the cost.关键词：access controller;multi-board communication;load balance;dynamic regulation
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发布时间： - 摘要：As the performances of the processing equipment of such networks as WLAN are affected when the Network Address Translation（NAT） function is enabled,this paper studies its realization in OCTEON chips.On the basis of analyzing the acceleration properties of OCTEON chip hardware,this paper introduces the software design framework with separated data and control planes and discusses the special task scheduling mechanism for the chip and presents an OCTEON chip-based NAT function implementation scheme.The experimental results indicate that this program greatly improves the NAT transition performance and has a good practicability.关键词：WLAN;NAT;hardware scheduling;simple executive
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发布时间： - 摘要：<正>2012年11月29日,从迪拜举行的世界电信标准大会上传来振奋人心的消息:由武汉邮科院在国际电信联盟ITU-T第13研究组主导制定的Y.2770标准获得世界电信标准大会最高级别会议（世界电信标准大会WTSA）批准,正式成为国际电联标准,也是全球首个互联网业务感知和内容识别的国际标准。
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