最新刊期
卷 ， 期 6 ， 2013
- 摘要：Dynamic Routing and Wavelength Assignment（RWA）is important in optical networks,which have a direct bearing on their QoS.This paper presents an improved Ant Colony Optimization（ACO）algorithm for this issue,which enhances the optimum pheromones of the ant colonies and converges them in accordance with the optimal solution in these colonies and increases the guiding role of the global information for them so as to achieve still better results.Simulation results indicate that compared with the conventional ACO algorithms,this improved one significantly reduces the blocking rate and improves the network QoS.关键词：optical network;WDM;dynamic RWA;ACO algorithm;blocking rate
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发布时间： - 摘要：In order to effectively reduce the burst loss probability of Optical Burst Switching（OBS）networks,the existing optical buffering schemes based on priority and burst segmentation are studied and improved in the case of multi-wavelength channels.In the improved scheme combined with the priority and burst segmentation mechanism,a cross-type optical buffer structure is introduced to buffer the segmented bursts and also the judgment of the idle channels and optical buffer delay time to ensure lower packet loss rate.The simulation results show that this scheme can effectively reduce the packet loss rate and guarantee the QoS of different priorities in OBS networks,thus improving the performance of the entire network.关键词：OBS;priority;optical buffer;segmentation;loss rate
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发布时间： - 摘要：In view of the deficiencies of the Session Initiation Protocol（SIP）-based authentication mechanism and forgery attacks,this paper proposes an improved hash algorithm-based SIP authentication mechanism,which realizes the mutual authentication between the user and the server using a dynamic key negotiation mechanism and provides one key authentication function in one transaction.The security analysis shows that this mechanism improves the protocol authentication security,prevents the replay attack,forgery attack and ensures the non-repudiation of the data sources.关键词：SIP;authenticate mechanism;key negotiation;hash algorithm
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发布时间： - 摘要：For the purpose of extracting any 1～8 bytes as required from the 64-bit ODU2 data stream stored in the buffer memory in the course of ODU2 segmentation in the OTN-based data packet switching technology,an adaptive ODU2 data splitting and rearrangement circuit structure is designed in a top-down way and implemented by using Verilog-HDL and the function simulation and logic synthesis are conducted.The results show that the data splitting and rearrangement structure can operate at up to 280MHz,significantly improving the efficiency of ODU2 data flow cutting.关键词：data sequence rearrangement;ODU;data segmentation;OTN;packet switching
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发布时间： - 摘要：In order to absorb the frequency offset generated due to source and destination clocks from different sources in Optical Transport Networks（OTN）,a circuit is designed by asynchronous mapping,in which sync clock-based ODU0 that generates uniform clock gaps is mapped to ODU1 and the clock gaps are generated in the mapping by asynchronous FIFO.The client data is processed by this clock and mapped into appropriate time slots.Simulation and FPGA test results indicate that this circuit can complete the traditional mapping from ODU0 to ODU1 in real-time and accurately.Compared with the traditional circuits,it greatly decreases the usage of PLL and makes the circuit more economical.关键词：OTN;mapping;clock gap;asynchronous mapping
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发布时间： - 摘要：The L2TPv3 protocol specification RFC 3931refers to the necessity of considering IP fragmentation in the protocol implementation,but fails to give a specific solution.On the basis of the existing solutions to Path Maximum Transmission Unit Discovery（PMTUD）and the advantages of several solutions,it proposes a specific solution suitable for L2TPv3,which takes into consideration the existence of both old and new formats of Internet Control Message Protocol（ICMP）messages in the existing networks,thus enhancing its applicability.关键词：L2TPv3;MTU;PMTUD;ICMP;fragmentation
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发布时间： - 摘要：Multiple Chinese carriers commonly use SDH,but not Ethernet interfaces for their backbone router network interlinks,so as to simplify their network operation,maintenance and management.On the basis of analyzing high-rate transport technologies and optical interface formats,this paper discuses the technical feasibility of adopting OTN interface format in highrate interlinks of backbone router networks and the need of supporting OTN overhead in the routers.It conducts laboratory tests on the functions and capabilities of the OTN interfaces of the routers of several venders,verifying that routers developed in compliance of the existing standards and specifications satisfy the requirements for the maintenance and management of backbone router networks in terms of functions,capabilities and interworking.关键词：OTN;interface;router
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发布时间： - 摘要：The Optical Distribution Network（ODN）is an important component part of FTTH networks and its quality is a focus of attention of project owners.On the basis of the performance test data statistics of the sampled ODN products,this paper summarizes the common defects of the main ODN products,analyzes their causes in details and put forward four measures for improvement.To control the quality of ODN products,it is necessary for ODN manufacturers,users and the relevant administrative departments to make joint efforts.关键词：ODN;FTTH;quality control;cause of defects;PON
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发布时间： - 摘要：In view of energy constraint in ultraviolet communication networks,this paper designs and realizes a Medium Access Control（MAC）layer power control mechanism suitable for ultraviolet communication so as to reduce node energy consumption and inter-node interferences,extend network life cycle and increase system capacity.Simulation and experimental results indicate that this mechanism achieves power control on the platform of ultraviolet communications under the premise of ensuring the QoS of user communication and lays a solid foundation for building ultraviolet Ad hoc networks in the future.关键词：ultraviolet communication;MAC;power control;FPGA
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发布时间： - 摘要：<正>科技论文的引言是简要说明研究的主要目的、范围,即为什么写这篇论文以及要解决什么问题;前人在本课题相关领域内所做的工作和尚存的知识空白,作简要的历史回顾和现在国内外情况的横向比较;理论基础、技术路线、实验方法和手段,以及选择特定意见方法的理由;预期研究结果及意义。
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发布时间： - 摘要：From the market analysis of small bending-radius G.657 Single-Mode Fibers（SMF）,this paper comes to the conclusion that their usage currently account for 2.3% of the total SMF usage in China and its demand will constantly grow with the development of FTTH.In view of this,it makes a detailed study of the evolutions of the international and national technical standards for the G.657 SMF.For example,the latest ITU-T G.657 standard increases the fiber mode-field diameter to（8.6～9.5）±0.4μm,increases the requirements of 1 383nm wavelength attenuation of G.657 Bfibers to less than or equal to 0.40dB/km and decreases their attenuation coefficients from 0.50dB/km to 0.40dB/km at 1 310nm wavelength.It is expected that the domestic fiber manufacturers can timely adjust their fiber development and production in compliance with the changes of the international standards to meet the market demand.关键词：SMF;market;technical standard;bending-insensitive
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发布时间： - 摘要：On the bases of the study on defective fiber ends,this paper proposes an improved method for obtaining the geometric parameters,which is based on gray-scale image threshold segmentation and elliptic boundary point selection and fitting,and extracting the edge point of the defective fiber by using the feature that the qualified fiber cladding and core edges have the same concentric circles.This feature can effectively remove the interference point.Compared with the two commonly used methods that are based on grayscale threshold segmentation and feature data point collection and on Canny operator edge detection and elliptic fitting respectively,this method figure out the geometric parameters of defective fiber ends more accurately.关键词：fiber end;geometric parameter;ellipse fitting;image processing
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发布时间： - 摘要：Mostly built on the electric power towers as overhead lines,electric power optical communication cable lines are often subject to sandstorm destructions.In view of the their impacts on the normal operation of the cable lines,this paper explains the destructions in two aspects,short-term severe damage and long-term slow erosion and describes the relevant damages and harms to these lines.In addition,it performs tests on the selected optical cable lines in actual field operation,analyzes the test results and measures the commonly used cables in the lab.On the basis of the field and laboratory test results and the field operation experience,it gives suggestions and advices for coping with short-term severe destruction and long-term slow erosion effect on the optical cable lines.关键词：sandstorm;chromatic dispersion;polarization mode dispersion（PMD）;optical fiber cable performance
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发布时间： - 摘要：This paper introduces the detection of the weak sinusoidal signals of Lock-in Amplifiers（LIA）by using In-phase Quadrature（IQ）dual-way reference signals.It first uses the atom pairs of the atomic reservoir as the reference signals by sparse decomposition and searches for the optimal atom pair by using the Matching Pursuit（MP）algorithm.Then,it decides the best phase angle from this atom pair and thus synthesizes the optimal atom.From this optimum atom it obtains estimated useful input signals and detects the sine signals in the input signals.Compared with the single way digital LIA,this approach is better in computational efficiency as the computation speed is doubled and inherits the advantages of the former.关键词：weak signal detection;LIA;sparse decomposition;MP algorithm
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发布时间： - 摘要：As burst optical packets have the feature of bursting and large dynamic scope,fast and accurate detection of their optical power is difficult.This paper briefly introduces the basic principle of optical power monitoring and describes the use of the use the fast sampling and holding technology method for its implementation.Furthermore,it uses this method to design a monitoring circuit and accomplishes the relevant calibration method.The experimental results show that with high accuracy and large dynamic scope this method meets the requirements for the burst optical power monitoring and greatly lower the speed requirement for A/D convertors.关键词：sampling;burst;monitoring
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发布时间： - 摘要：The conventional WDM are usually large in size,which has become the bottleneck of the photonic integration.This paper designs a type of three-wavelength（1 310nm,1 490nm and 1 570nm）photonic crystal WDM by utilizing the multimode interference effects of photonic crystals.The simulation results show that the insertion loss of this device for the three wavelengths is all less than 0.45dB,and the channel isolation is all larger than 15dB.In addition,its size is only 37#m $13#m.easy to be optically integrated and superb in performance.关键词：photonic crystal;multimode interference;self-imaging effect;WDM
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发布时间： - 摘要：On the basis of the principle of nonlinear optics,the conjugated metallic periodic structure with nonlinear optic material can realize all-optical switches.It is found from the numeric simulation of the electromagnetic field near nano-structure that its surface plasmons demonstrate distinct enhancement of the local field,which greatly increases the third-order nonlinear effect of the nonlinear material and makes the all-optical control still more dominant,thus reducing the threshold power of the switches and realizing super-fast response speed.It is expected to be widely applied in the future all-optical communication networks.关键词：metallic periodic nano-structure;all-optical switch;third-order optic nonlinearity
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发布时间： - 摘要：Having the functions of both lighting and communications,Visible Light Communication（VLC）is an emerging wireless optical communication technology.Having many advantages and broad prospects of applications,it has become a research hotspot in recent years.Combining with Multiple-Input Multiple-Output（MIMO）and other technologies,it can greatly increase the communication rate.Researchers have proposed multiple MIMO models and techniques applicable to VLC and there are multispot-diffuse MIMO,pixelated MIMO,non-imaging and imaging MIMO systems in the global researches on MIMObased optical communications systems.This paper investigates these systems and summarizes the advantages and disadvantages of various optical MIMO communication models,laying the foundation for deep understanding and further research on MIMObased VLC.关键词：VLC;MIMO;multispot diffuse;pixilated;non-imaging VLC;imaging VLC
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发布时间： - 摘要：In order to improve the processing efficiency of Wireless Local Area Network（WLAN）Access Controllers（AC）for large traffic network data,this paper studies and tests the ContentAware mechanism for the switching chips.Compared with the load balancing mechanism for software implementation,it presents a load balancing mechanism based on real-time control of switching chips.It separates the data plane and control plane,balances the service data,implements the real-time control of load balancing and avoids the backplane interface capacity limits of the separate load boards used in the software mechanism,effectively improving the throughput and stability of the multi-board AC.关键词：AC;load balancing;data distribution;ContentAware
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发布时间： - 摘要：In order to improve the reliability of IP Radio Access Networks（IP RAN）and reduce the losses caused when they break down,the existing network protection technologies,such as LSP protection,PW redundancy protection,VPN FRR,VRRP are studied.The network deployment structures commonly used in present projects are investigated and a general model containing access layer,convergent layer and core layer summarized.On the basis of analyzing faults occur in various situations,a scheme that integrates multiple technologies is designed so as to ensure the normal operation of the networks,improving network reliability and providing certain reference for network deployment.关键词：IP RAN;LSP;FRR;network reliability
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发布时间： - 摘要：Slot waveguide is characteristic of wide frequency band and high aperture efficiency.This paper calculates the radiation slot parameters of the single-ridge waveguide slot antenna array using MATLAB software programming according to AdolfChebyshev aperture distribution method and designs an 8-slot single-ridge waveguide slot array antenna.Furthermore,it optimizes the gap parameters and simulates the bandwidth characteristics of the antenna using the three-dimensional electromagnetic simulation software HFSS.The results indicate that the size parameters of the single-ridge waveguide slot affects the bandwidth and relative to the rectangular slot waveguide,the VSWR bandwidth of the single-ridge slot is substantially broadened,which provide a valuable reference for the applications of slot ridge waveguides in communications and radar antennas.关键词：single-ridge waveguide;slot antenna;gap parameter;bandwidth
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发布时间： - 摘要：<正>2013年11月3日,国家科学技术部在武汉邮电科学研究院组织召开会议,对光纤接入（FTTx）产业技术创新战略联盟（武汉邮电科学研究院）组织完成的国家科技支撑计划项目《低成本光纤接入网关键光电子器件及装备研制》进行验收。来自科技部相关部门的领导以及国内11位光通信领域知名专家共同对项目进行了审议。
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