最新刊期
卷 ， 期 4 ， 2015
- 摘要：Telecom carriers in intense competitions urgently require full service solutions to Fixed-Mobile Convergence（FMC）networks.China Unicom promotes G.metro proposal in ITU-T to cope with the challenges that FMC faces in the assess domain,such as bandwidth,survivability and cost.In view of such requirements,this paper proposes a novel WDM access ring with the self-healing function for G.metro and verifies its performances and survivability.The results indicate that this access ring is highly reliable and low in cost,suitable for FMC.关键词：WDM;access;FMC;self-healing
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发布时间： - 摘要：Laser frequency offset and phase noise are important factors that limit the Coherent Optical Orthogonal Frequency Division Multiplexing（CO-OFDM）system performances.This paper proposes a novel scheme based on differential pre-coding and Multi-Carrier Differential Detection（MCDD）algorithm,which can jointly compensate the laser phase noise and frequency offset,theoretically derives the principle of the frequency offset and laser phase noise in CO-OFDM systems and the working mechanism of the MCDD-based compensation scheme,and conducts system simulations in different OSNRs,laser frequency offsets and linewidths.The simulation results indicate that this scheme has good compensation effects and large compensation scope and effectively improves the CO-OFDM system performances even without introducing extra system overhead.关键词：CO-OFDM;laser frequency offset;laser phase noise compensation
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发布时间： - 摘要：In view of the complex network information and the increasing coding delay arising from large amounts of Gate and Report message exchanges in the Network Coding（NC）control process of the conventional hybrid Fiber-Wireless（FiWi）access networks,we design an NC-supported software-defined FiWi network architecture and an openflow-based NC control scheme.The simulation results show that the proposed centralized control method and its implementation scheme in the software-defined FiWi network architecture can reduce the amount of the controlled information,improve the bandwidth utilization rate,effectively reduce the data transmission delay and improve the network throughput.关键词：FiWi network;software-defined network;NC
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发布时间： - 摘要：A priority-based Burst data packet Slicing（BS）scheme considering path correlation in Optical Burst Switching（OBS）networks is proposed in this paper.This scheme does not only effectively support multi-services,but also fully considers multipath contentions.Results show that both the length of paths and the number of correlated paths may affect data loss in OBS networks.关键词：OBS;burst segmentation;path correlation;quality of service
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发布时间： - 摘要：On the basis of the Optical Internetworking Forum（OIF）protocol standards,we establish for the first in the industry a cell switching-based Packet Optical Transport Network（POTN）system,which simultaneously supports the cross-connect and packet switching of the Optical Channel Data Unit k（ODUk）with a switching capacity of over 10Tbit/s,and have it tested in practical projects.The test results indicate that this technology meet the requirements of POTN system in ODUkjitter,latency and bit error rate,and of data services in packet loss and latency,verifying its feasibility and practical applicability.关键词：POTN;cell switching;ODUkcross-connect;packet switching
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发布时间： - 摘要：On the basis of the OptiSystem platform,we present a nonlinear separation model for evaluating the impacts of FourWave-Mixing（FWM）noise on the system performance and also a novel dispersion map.By using this model,we simulate the FWM noise of the co-polarization Dense Wavelength Division Multiplexing（DWDM）systems with 33 channels.The simulation results show that under the given system conditions,apure Differential Phase-Shift Keying（DPSK）（i.e.all channels are DPSK modulated）system has better nonlinear tolerance than a hybrid DPSK and On-Off Keying（OOK）system.For novel dispersion management systems,with the increase of bit rate and incident optical power per channel,the impacts of FWM noise on the performance of the hybrid DPSK and OOK DWDM system are greater than those on the pure DPSK system.关键词：DWDM;FWM;DPSK;OOK
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发布时间： - 摘要：Interference arising from abnormal uplink optical signals in faulty ONU is a common and hardly entirely avoidable problem in PON networks,which seriously threatens the steady network operation.This paper describes several behaviors of the interferences and their possible causes,and summarizes two typical long-shining alarm detection methods,discusses the location of the faulty ONU,compares their advantages and disadvantages and gives a mechanism for abnormal protection against the interferences at the ONU side.关键词：PON;ONU;interference;long-shining
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发布时间： - 摘要：The core node is a key device of optical switching networks and its performances have a direct bearing on the main indexes of the switching networks such as throughput and latency.This paper presents a wavelength converter-based strictly nonblocking switching core node structure and on this basis proposes three scheduling algorithms.Then it verifies their correctness by numerical analysis and experimental simulation and examines the variations of their blocking rates in different scenes,such as with or without wavelength conversions and service priority considerations.It is concluded that the proposed structure has fairly low blocking rate.关键词：optical switching structure;scheduling algorithm;blocking rate;wavelength converter
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发布时间： - 摘要：On the basis of the enhanced Telecom Operations Map（eTOM）O/M model,this paper studies the O/M model for PON,builds an intelligent fiber-optic network architecture and investigates its intelligent photoelectric devices and ONU.Considering the service and policy requirements of the operators,this paper focuses on the key technologies for PON intelligence tests.Through the data acquired from the intelligent OTDR+reflector tests,it verifies that the built-in OTDR+optical dielectric film reflector is the optimum scheme for PON intelligence test.关键词：eTOM model;PON;intelligence;reflector
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发布时间： - 摘要：In order to satisfy the increasingly higher requirements for ultra-long haul transmission in ultra-high voltage grid constructions,we propose a new technical approach:optical repeaters on transmission line towers.We analyze the theoretical basis for this approach,design the relevant technical scheme and realize the first pilot project of optical repeaters on transmission line towers in Shicheng-Huanxian section of the Hami-Zhengzhou fiber-optic communication project for ultra-high voltage DC power transmission.The section project has been cut over and operating steadily,verifying the feasibility of this solution.With the constant construction of power grids in China,this solution will find still wider applications.关键词：ultra-long haul transmission;repeaterless transmission;optical repeater on transmission line towers;line amplifier
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发布时间： - 摘要：This paper first introduces the comprehensive applications of the fiber-optic communication technology in phased array radar systems and then describes the optical transmission of analog local oscillating signals,clock synchronization signals,phase assignment technology,such as optical signal multiplexing and such subsystems as fiber-optic time delay line and optical transmission of digital echoing signal.Finally,it discusses its principles,scheme block diagram and parts of the technical indexes,providing valuable reference for the comprehensive applications of the optical transmission technology in phased array radar systems.关键词：fiber-optic communication;phased array radar;phase assignment technology
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发布时间： - 摘要：For the purpose of accurately investigating the dispersion and transmission characteristics of thin-clad Chirped LongPeriod Fiber Gratings（CLPFGs）,this paper analyzes the differences of the effective Refractive Indices（RIs）and the center wavelengths in the core mode yielded from the two-and three-layered medium models of a uniaxial-crystal fiber.On the basis of these differences,it numerically analyses the effects of different cladding radii and cladding mode order on CLPFG dispersion properties.The results show that the core-mode effective RIs of the two fiber medium models differ significantly when the cladding radius and cladding mode order are small and for the fiber gratings of both models,either reducing the cladding radius or increasing the number of the cladding mode order is conducive to the increase of dispersion.The analytical method and conclusions presented in this paper provide a theoretical basis for the analysis and design of CLPFG.关键词：fiber optics;uniaxial-crystal fiber medium model;CLPFG;dispersion compensation;spectrum
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发布时间： - 摘要：Fast cross-correlation calculation of the signals received in two channels are realized by using the Fastest Fourier Transform in the West（FFTW）algorithm,real-time location of the Mach-Zehnder（M-Z）perimeter protection systems improved,M-Z perimeter protection equipment set up and vibration signal location tests performed in a 6km-long cable with an accuracy of 21 mat a sampling rate of 20 MHz with the location calculated in less than 0.5s.The experimental results indicate that compared with the conventional Fast Fourier Transformer（FFT）algorithm,this algorithm calculates significantly faster.关键词：FFTW;perimeter protection;M-Z;cross-correlation algorithm
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发布时间： - 摘要：When identical weak grating arrays go through hybrid TDM/WDM,shadowing effect and multiple reflections in the grating arrays affect the reflected signals.This paper performs simulation calculation and analysis of the time domain reflected signals in the grating arrays.The shadowing effect and the multiple reflections will not cause the drift of the grating center wavelength,but may lead to the decrease of the reflection intensity at the grating center wavelength.If every single grating in the arrays possesses high reflectivity,owing to the shadowing effect,it may not be possible to detect the gratings at its distal end arrays,resulting in failure to increase the number of multiplexed gratings.However,when the single grating reflectivity is too low,the weak reflected signals in the grating array will increase the difficulty in signal detection.关键词：weak grating;grating array;TDM;shadowing effect;multiple reflection;simulation calculation
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发布时间： - 摘要：In order to generate flat Optical Frequency Comb（OFC）with equal frequency spaces,a novel scheme for the generation of super-flat dual optical frequency combs is demonstrated on the basis of the intensity modulation property of single MQW-based electro-Absorption Modulator（EAM）.In this scheme,the reversed bias voltage and the radio frequency-driven signal amplitude of the MQW EAM are precisely controlled by placing a rectangular optical filter before the EAM and a dual optical frequency comb with a flatness of 0.01 dB is obtained after filtering out the center line of the spectrum.The scheme is simulated with the software Optisystem7.0.In this simulation,dual optical frequency combs symmetrically at the sides of the centerline of the spectrum both with bandwidth of 300 GHz,15spectral lines,interline spacing of 20 GHz and flatness of 0.01 dB can be generated by all laser light sources with different linewidths（100kHz,10 MHz and 20 MHz）.关键词：dual OFC;EAM;flatness
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发布时间： - 摘要：In this paper,a single array FBG-based Optical Arbitrary Waveform Generation（OAWG）system is proposed,which consists of two parts:optical frequency combs generation and pulse shaping.The former is obtained by compressing a dual wavelength beat light using the Self-Phase Modulation（SPM）effect and the latter composed of FBG array,polarization controllers（PC）,Fiber Stretchers（FS）and a polarizer.The polarization states of the spectral lines at different wavelengths are different after passing through different number of PC and the amplitude of each line attenuates to a different extent after passing through the polarizer.The phase controllers adjust the phase of each spectral line by manipulating the length of the fiber.Using this system in experiments and simulation,we obtain waveforms with a frequency of 125 GHz similar to triangular and Gaussian waves.关键词：FBG;polarization controller;arbitrary waveform
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发布时间： - 摘要：On the basis of the periodic modulation technology,this paper systematically studies the differences in quantum properties of optical signal transmissions between 3-optical fiber coupling systems with linear and equilateral triangular structures respectively.In the tight-binding approximation,it obtains the coupled mode equations for the optical signal transmission in the3-optical fiber coupling system and further simulates the impacts of different system parameters on some major quantum phenomena.The results show that different structures will lead to such property changes as tunneling and coherent tunneling destruction,thus affecting the energy distribution and oscillation frequency of the optical signals..These study results are instructive to the design of novel optical cross-connect connector and other fiber-optic devices.关键词：optical communication;quantum tunneling effect;coherent tunneling destruction
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发布时间： - 摘要：Visible Light Communication（VLC）technology is considered to be a promising solution to the future indoor wireless communications.In this paper,we investigate the effects of various external interferences on the performance of optical Multiple-Input Multiple-Output（MIMO）systems.On the basis of an indoor MIMO VLC system model,we first derive the system BER expression and analyze the relationships between the BER and different factors.Then,in line with this expression,we analyze in detail the effects of different types of interferences on the BER.Finally,we simulate the interference scenarios in practical conditions and give the basis for distinguishing different interferences and making reasonable handover decision on the basis of the simulation result analysis.关键词：indoor VLC;MIMO;BER;external interferencezz
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发布时间： - 摘要：Existing in Traffic Flow Template（TFT）of the Evolved Packet System（EPS）bearer,Packet Filter（PF）is one of the major component parts of the EPS systems.On the basis of the detailed analysis of the PF storage scheme,we propose a new EPS bearer-based PF storage and matching method.We store the PF in the bearer information units according to the corresponding bearer identifications.At the same time,in order to realize PF priority-based IP data packets matching,we work out a PF information table sequenced by priority,which we can use to quickly find the storage location of PF with the corresponding priority and complete the matching of IP data packets.关键词：EPS bearer;TFT;PF;IP data packet matching
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发布时间： - 摘要：This paper makes a comparative analysis of the performances of two modulation modes commonly used in free space optical communications theoretically and experimentally,aimed at finding an optimal modulation method for suppressing atmospheric turbulences.In analyzing the BER of OOK and DPSK modulations in Gamma-Gamma channels,it introduces the generalized hypergeometric method to the analysis and establishes a system for simulation by using Marlab.The experimental results indicate that the performance of DPSK modulation-based coherent and balanced detection is 3.21 dB higher than that of OOK modulation-based direct detection and that in the comparison between the dual-tube balanced detection and the single-tube detection,the former is superior in BER,about 21.6dB higher,verifying that DPSK balanced detection-based scheme is feasible and superior.关键词：atmospheric turbulence;balanced detection;OOK;DPSK
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发布时间： - 摘要：In this paper,a unipolar channel-based OCDMA system that can use bipolar sequences is introduced and a method for constructing bipolar chaotic sequences with good correlation property by using the 3rd-order Chebyshev mapping described.With the bipolar chaotic sequences applied to the above-mentioned OCDMA system,its performance is analyzed.Under the condition of complete asynchronization,the expressions for SNR and BER are derived and the BER curves varying with the number of users simulated and compared with the similar systems based on the Gold sequences.The results indicate that with the same number of users,those systems that are based on the chaotic sequences have lower BER.关键词：fiber-optic communication technology;OCDMA;Chebyshev mapping;chaotic sequence
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发布时间： - 摘要：In order to better eliminate such phenomena as large amounts of redundant information and imbalanced node energy consumption in the covering process of Wireless Sensor Networks（WSN）,this paper proposes an optimal covering algorithm for node energy balance.By using the subordinate relationship between the sensor nodes and destination nodes in the monitoring area,this algorithm builds a network model and gives such dependence.Then,on the basis of the dependence and the probability theory,it solves the expected value of the sensor nodes in covering the destination nodes and then calculates the least number of sensor nodes required for covering the monitoring area.The experimental results indicate that this algorithm cannot only use the least sensor nodes to effectively cover the monitoring area,but also resist the generation of redundant information data,thus extending the network lifecycle.关键词：WSN;probability model;coverage rate;network lifecycle
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发布时间： - 摘要：This paper introduces the cell handover procedure specified in the TD-LTE（TD-SCDMA Long Term Evolution）system,and focuses on the random access procedure in handover execution.In line with the features of the TD-LTE protocol conformance test and the practical development experience,this paper analyzes the handover test simulation diagrams by performing the Radio Resource Management（RRM）different frequency handover test cases and can see from the simulation data the random access initiated by the terminal to the target cell according to the preamble configuration of the source cell,effectively verifying the protocol conformance of the random access procedure in the handover.
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发布时间： - 摘要：This paper first establishes a Markov model and a state transition matrix for the state of an optical communication system and calculates the steady-state probability of the network system by using the balancing features of the steady-state Markov model and its state transition probability.Then,it obtains the system steady-state probability through probability calculations in the light of the network topological structure and the protection mechanism information.Finally,on the basis of the assessment of the network system steady-state probability,it proposes a routing algorithm for the free-space optical communication system.This algorithm takes into consideration the fast mobility features of network nodes,link bandwidth,the shortest path and the constraints of the number of transceivers.The simulation study results indicate that the routing algorithms based on system steady-state probability assessments are superior to conventional ones in terms of reliability in practical applications.关键词：steady-state assessment;optical communication network;routing algorithm
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