最新刊期
卷 ， 期 5 ， 2013
- 摘要：Optical switching system is the core part of the wavelength routing and central data transmission in the optical network,which is currently developing towards high-rate,multiport and high-capacity optical switching.This paper explains that the router technology of Arrayed Waveguide Grating（AWG）combined with high-rate tunable lasers is the most effective scheme for realizing ns-grade switching time in a large-scale optical switching system.Furthermore,it describes schemes with different architectures of AWGR in four aspects,i.e.cyclicity,series,parallel,series-parallel.关键词：optical switching system;AWG;wavelength routing;tunable lasers
- 2
- |
- 158
- |
- 7
发布时间： - 摘要：The traditional 16QAM phase estimation algorithm for coherent optical systems chiefly employs QPSK partitioning.However,owing to the influence of amplifier ASE noise,the radial movement of the constellation point seriously affects the accuracy of the phase recovery.In view of the different extent of the effects,this paper makes a detailed analysis of the classified amplitude threshold in the QPSK partitioning and proposes an analytical model that takes the relationship of Optical SNR（OSNR）,the length of summing window,and the threshold radius into account.The model also induces a group of weighted coefficients into phase estimation.Monte Carlo simulation results show that the improved method effectively increases the precision of phase recovery with still lower BER.关键词：carrier phase recovery;coherent optical detection;radial effect;QAM
- 2
- |
- 149
- |
- 1
发布时间： - 摘要：To optimize the performance of the Routing and Wavelength Assignment（RWA）algorithm based on a physical impairment model for optical（transparent）networks,this paper constructs a simplified impairment model by analyzing the features of multiple physical impairments and proposes a directed flooding RWA algorithm based on Resource Reservation Protocol-Traffic Engineering（RSVP-TE）,i.e.KDF-IRWA algorithm,which allows the source node to send PATH packets to the destination node through multiple candidate paths.These PATH packets independently collect the path information of various links in the selected path,which converge at the destination node and is calculated and compared,thus avoiding packet re-sending arising from the failure in path setup for the first time in the classical algorithms and improving the efficiency of the algorithm.The simulation results indicate that this algorithm can effectively reduce the time,increase the probability of success in path setup and reduce network blocking rate.关键词：optical network;physical impairment;RWA algorithm;RSVP;flooding routing strategy
- 2
- |
- 51
- |
- 2
发布时间： - 摘要：Along with the increase of transmission capacity and distance driven by broadband applications,the Non-Linear Distortion（NLD）of signals in fiber-optic transmissions has become one of the major limiting factors to fiber-optic communication systems.This paper summarizes the latest developments of Non-Linear Compensation（NLC）technologies in the optical and electrical domains,analyzes and compares their mechanisms,characteristics and practical applications with the focus on Digital Signal Processing（DSP）-based NLC for digital coherent optical communication systems and the trend of their future development.关键词：fiber-optic communication;nonlinear compensation;DSP;digital coherent system
- 5
- |
- 196
- |
- 3
发布时间： - 摘要：As signal light spots in the coherent optical detection system change with RF signals because of acousto-optic deflection effects,we study the relationship between the spot structure and the detecting efficiency on the basis of a spot overlapping physical model,analyze the effects of beam collimation,active photosensitive surface radius of detectors and optical local oscillator energy matching on the coherent detection efficiency.The computer simulation and experimental tests demonstrate that taking spots with uniformly distributed energy as local oscillator spots is conducive to improving the efficiency of the coherent detection of the overlapping spots when they drift within a certain range,e.g.when the spatial mismatching angle is in the range±0.5rad,the overlapping efficiency declines by less than 5%,and that the system beam collimation is effectively ensured by light spot compression and collimation processing,the energy utilization ratio of overlapping spots is higher and the system optical matching is better.关键词：acousto-optic deflection;coherent detection;beam collimation;light spot overlapping;detection efficiency
- 2
- |
- 52
- |
- 1
发布时间： - 摘要：On the basis of analyzing the effects of the serial correlation among the subcarriers of the CO-OFDM system on its performances,this paper proposes a new approach,in which the SeLected Mapping（SLM）method and the clipping method are combined.This approach optimizes the subcarrier serial correlation and mitigates the Four-Wave Mixing（FWM）effects that are mainly dependent on the former,thus improving the system performance.Theoretical analysis and MATLAB simulation results show that compared with SLM and clipping methods,this approach improves the sensitivity by about 1.8 and 3.4 dB respectively at the BER of10-3.关键词：CO-OFDM;serial correlation;FWM;SLM method;clipping method
- 2
- |
- 54
- |
- 4
发布时间： - 摘要：In this paper,we first introduce a novel multiplexing technology for realizing channel multiplexing i.e.Duty Cycle Division Multiplexing（DCDM）,which realizes multiplexing by assigning each user a different RZ duty cycle.Then we analyze the principles of its multiplexing and demultiplexing and design a demultiplexer using MATLAB.In order to verify its feasibility,we design a fiber-optic transmission system based on DCDM of three users by joint simulation with Optisystem and MATLAB.Simulation results verifies the feasibility of the system.关键词：DCDM;multiplexing;demultiplexer
- 2
- |
- 63
- |
- 6
发布时间： -
Design and implementation of integrated operation and management system for transmission trunk lines
摘要：In view of current lack of unified management and centralized supervision of line resource,maintenance and network quality for transmission trunk lines,this paper presents a GIS/GPS-based integrated operation,maintenance and management scheme on the basis of the extensive research on resource model,task flow and work scene,and designs and implements the functions of management process,information interaction,data validation and user interface.The practical application results show that this system significantly improves the efficiency of the operation and management of transmission trunk lines.关键词：transmission network;optical cable line;integrated operation and management system- 4
- |
- 40
- |
- 2
发布时间： - 摘要：Using CO2 laser as a light source,this paper investigates coupling the laser light into a Photonic Crystal Fiber（PCF）by using a lens.It first conducts the modeling and analysis of the laser light and fiber model by using the ZEMAX software and designs a novel low-loss Photonic Band-Gap（PBG）infrared PCF for transmitting 10.6μm CO2 laser light.Then,it completes the coupling by using a ZnSe lens with the structural parameters of r1=11.39mm,r2=-25.43mm,thickness of 3mm and BFL =11.16mm and finds that the distance between the waist and the lens is 1 102.50mm,that between the image waist and the lens is 17.30mm and the coupling value is 94%.关键词：CO2 laser;ZnSe lens;PBG-PCF;low loss;efficient coupling
- 2
- |
- 99
- |
- 1
发布时间： - 摘要：For ensuring the secure operation of power system communications,real-time monitoring of the running state of the OPtical fiber composite overhead Ground Wire（OPGW）is necessary.This paper presents a method on the basis of the Brillouin Optical Time Domain Reflectometry（BOTDR）technology,in which real-time monitoring is performed on the OPGW temperature and strain.Then,it calibrates the temperature and strain coefficients of G.652optical fiber in OPGW.On the basis of the experimental results,it studies the temperature and strain distribution of OPGW in field operation and analyzes the faults brought about by temperature and strain using the differential method and the relative value method.The results indicate that the BOTDR-based online monitoring system can realize real-time measurement of distributed temperature and strain and fault location for OPGW.关键词：BOTDR;OPGW;temperature;strain;on-line monitoring
- 2
- |
- 161
- |
- 12
发布时间： - 摘要：Sharp increase of network data amount causes rapid bandwidth consumption and network congestion,which places still higher requirements on Packet Transport Network（PTN）chips in terms of forwarding capacity,clock rate,congestion avoidance and flow management.In order to improve the clock rate and reduce the circuit design complexity of the IP multicast lookup circuits in these network chips,this paper completes this circuit design by adopting pipeline architecture and looking up the intermediate state information using the RAM record.It conducts hardware verification on Altera series FPGA development board EP4SGX230KF40C2ES and the results show that this circuit can complete the IP multicast lookup function and works steadily at 200MHz.关键词：packet transport network;IP multicast;lookup
- 2
- |
- 33
- |
- 0
发布时间： - 摘要：The optical coherent receiver with Data-Aided Maximum Likelihood（DAML）carrier phase estimation has become one of the coherent reception modes to be considered for tests in the optical communication field in the near future.This paper studies the initiation of this type of receiver and on this basis proposes a cold-start scheme.Simulation verify the feasibility of this scheme.Furthermore it optimizes this scheme and simulation results show that when both the parameters of the Mth power algorithm and the DAML algorithm take the optimal values,the cold-start scheme achieves the best performance.关键词：coherent optical communications;carrier phase estimation;DAML;cold-start
- 2
- |
- 43
- |
- 0
发布时间： - 摘要：As it is necessary to fast respond the variations of optical detection current and maintain constant optical power for the applications of burst-mode optical modules in the system,this paper designs an Automatic Power Control（APC）system for the burst-mode optical communication laser driver.Controlled by Digital Signal Processing（DSP）,this system can fast set up output bias current,keeping the transmitting optical power and extinction ratio constant over the whole range of temperature.In the burst mode,it can cut off or start up the output bias current in 2ns,satisfying the requirements of the burst-mode EPON system.关键词：automatic power control;digital signal process;EPON;burst-mode
- 3
- |
- 52
- |
- 4
发布时间： - 摘要：For measuring delay and BER in the process of data transmissions,this paper designs a high-rate data transceiver circuit with fibers as the transmission media.Using TLK1501as the interface device from electric signals to optical signals,it designs the unit circuit at the receiving and transmitting ends by using FPGA,compares the received data and conducts BER analysis.The experimental results show that this circuit design is highly reliable and practical.关键词：FPGA;optical transceiver module;fiber transmission
- 2
- |
- 120
- |
- 3
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;以及的理论基础、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。引言部分一般分为三到四个层次:（1）由研究背景、意义、发展状况等内容组成,其中还包括某一研究领
- 3
- |
- 50
- |
- 0
发布时间： - 摘要：This paper studies the time-domain autocorrelation matching method for reducing the Peak-to-Average Power Ratio（PAPR）of the Orthogonal Frequency Division Multiplexing（OFDM）system.The main idea of this method is to add a random sequence generator in time domain,in which the random sequences are overlapped to the original signals so as to reduce the PAPR of the system and perform blind detection at the receiving end.As the signal processing in this method takes place in time domain,the computational complexity can be reduced in just one IFFT operation.Simulation results indicate that similar PAPR and Bit Error Rate（BER）performances can be acquired in this method to those in traditional SeLecting Mapping（SLM）method but the computational complexity is much more mitigated,thus verifying the effectiveness of the proposed method.关键词：OFDM;PAPR;signal blind detection;time-domain autocorrelation matching
- 2
- |
- 63
- |
- 3
发布时间： - 摘要：With the tests and applications of IP Radio Access Networks（IPRAN）,there emerge many complex application scenes,e.g.full layer2PWE3for inter-ring protection of double node cross-ring service and using MS-PW and DNI protection or L2VPN transferred to L3VPN service.For these scenes,the conventional configurations are very complicated in modes and process.This paper introduces the complicated configuration steps of IPRAN in the above-mentioned scenes and presents the mapping substitution of the key nodes with a service scene template,incorporating all the tunnel,PW,PW redundancy and DNI that are required by the services rapidly once for all and thus improving the efficiency of E2E static service assignment in such scenes.关键词：IPRAN;complex scene;MS-PW;DNI;L2VPN;L3VPN
- 2
- |
- 84
- |
- 0
发布时间： - 摘要：In order to enhance the overall performances of wireless networks,this paper analyzes the influences of the binary back-off algorithm and the size of Contention Window（CW）used for the Distributed Coordination Function（DCF）of the Media Access Control（MAC）layer of IEEE 802.11 wireless networks in the fundamental working mode.It then optimizes the back-off mechanism by increasing the initial CW,cancel the Distributed InterFrame Space（DIFS）that busy channels need to wait for when they become idle but still have to be back-off and set up an intermediate value as a threshold so that different back-off algorithms are adopted when node transmission is a success or a failure.OPNET simulation results show that the improved algorithm can effectively reduce network access delay and improve the system throughput.关键词：IEEE 802.11standard;DCF;back-off algorithm;CW
- 2
- |
- 118
- |
- 3
发布时间： - 摘要：In this paper,a new method based on the reprocessing of power spectrum density is proposed to detect and estimate the PN sequence period of the M-ary spread spectrum signals in low SNR.In this method,the power spectrum of the received signals is first acquired and taken as input signals,their power spectrum is acquired again.Pointed impulses will emerge at the position of integer times of PN sequence period and the PN sequence period of the M-ary spread spectrum system can be estimated by detecting the intervals of these impulses.Theoretical analysis and computer simulation results show that this method can effectively estimate the PN sequence period and the less the information bits transmitted by each PN sequence,the better the estimation performance.关键词：SNR;M-ary spread spectrum;power spectrum reprocessing;PN sequence period
- 2
- |
- 77
- |
- 4
发布时间： - 摘要：In view of the occurrence of congestion in Access Point（AP）wireless scanning information reception at the AP in the network management system of large-capacity wireless Access Controller（AC）systems,this paper presents a new AP wireless scanning information processing mechanism,which improves the system resource utilization ratio by configuring OMC intermediate subsystems and isolating the data processing process.Experimental results prove that the simple network management protocol improves the performance of the WLAN network management system,especially in mounting multi-AP environment.关键词：simple network management protocol;performance management;wireless scanning;index
- 2
- |
- 34
- |
- 2
发布时间： - 摘要：On the basis of the SITE algorithm,this paper proposes a node coverage discrimination model based on the average distance of neighbor nodes（ADDM）for wireless sensor networks,which discriminate whether a certain node is redundant or not by computing the average distance between this node and all the neighbor nodes and the central angle of the overlapping area.Theoretical analysis and simulation results show that the ADDM improves the SITE algorithm,overcomes its failure to consider the contribution of those nodes with distances longer than radius of perception in covering redundant nodes,thus realizing the regional coverage with fewer nodes,reducing the number of active network nodes and prolonging the network life time.关键词：wireless sensor network;average distance;SITE algorithm;coverage discrimination
- 2
- |
- 33
- |
- 1
发布时间： - 摘要：Distributed Denial of Service（DDOS）is a common and destructive network attack.In order to minimize its impacts on network equipment,this paper presents a Netfilter-based strategy for preventing DDOS attacks on access controllers.Using the improved SYN Cookie technology,it executes a secondary development of Netfilter in the inner core of Linux,realizing a firewall against SYN Flood in DDOS.Test results indicate that this scheme effectively prevents network attacks,ensures the normal service of TCP with little performance loss and saves cost.关键词：Netfilter;access controller;DDOS;SYN Cookie;SYN Flood
- 2
- |
- 37
- |
- 3
发布时间： - 摘要：This paper discusses the acquisition of BOC signals in multipath fading channels.It first compares the acquisition performances in various channels using the currently superior acquisition algorithm on the basis of the models of multipath fading channels.Then it analyzes the impacts of the channels on the acquisition performances in connection with Rice factor K,multipath routing number Land multipath delay.Theoretical analysis and simulation results show that the larger the Rice factor K,the larger the acquisition function peak value and the better the acquisition performance,while the smaller the multipath routing number L,the less the side peaks and the better the acquisition performance.关键词：BOC signal;acquisition;multipath fading channel;Rice factor;multipath routing number
- 2
- |
- 106
- |
- 3
发布时间： - 摘要：<正>不久前,由烽火通信公司牵头承担的国家科技支撑计划项目《低成本高可靠FTTx光缆及外场设施关键技术研究与开发》顺利通过了由FTTx产业技术创新战略联盟组织的专家验收。此举标志着我国低成本、高可靠的FTTx光缆及外场设施核心制造技术取得了重大突破。随着FTTx建设的快速推进,能满足复杂施工条件下和恶劣应用环境下的光缆结构设计技术和规模化生产关键工艺技术,以及快速可靠的现场连接技术成为了制约我国实现光纤到户低成本、
- 2
- |
- 14
- |
- 0
发布时间：
- Postal code：430205
- Technical support is provided by Beijing Founder electronics co., LTD 鄂ICP备2022010197
鄂公网安备 42011202002092号 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
- Total Visits：75845
0