最新刊期
卷 ， 期 3 ， 2018
- 摘要：Considering the shortage of low bandwidth utilization and congestion of data transmission in traditional optical networks,we construct a Software Defined Network（SDN）-based virtual optical network that comprises of a packet network and an optical network,and propose a multi-path routing algorithm that optimizes the bandwidth allocation.Under the capacity constraints of the transmission link,we calculate the maximum load of each link and optimize the bandwidth allocation in multipath routing.With the help of ONOS and Mininet simulation tools,we verify that our algorithm can effectively reduce the delay of data transmission and avoid network congestion.关键词：SDN;packet network;virtual optical network;optimized routing algorithm
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发布时间： - 摘要：Recently,cloud technology is widely used in Data Center Network（DCN）.In order to ensure Quality of Service（QoS）in DCN,Equal Cost Multipath Routing（ECMP）algorithms and Dynamic Load Balancing（DLB）algorithms are employed as solutions.However,these algorithms only obtain local optimization results.In particular,the transmission delay and bandwidth utilization are not satisfactory when these algorithms are applied in the DCN overloaded environment.Considering the limitations of these algorithms,this paper proposes a load balancing scheduling mechanism for fat tree network data traffic under Software Defined Network（SDN）architecture from the perspective of global optimization.The mechanism evaluates the SDN node and link load by monitoring the global real-time parameters through the Ryu controller,and selecting the optimal forwarding path which meets the demand of traffic load.Experiments show that the scheduling mechanism proposed in this paper has significantly improved the performance of DCN services compared with the ECMP/DLB algorithm.关键词：SDN;DCN;evaluation;balance;simulation
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发布时间： - 摘要：With the large-scale deployment of Optical Transport Network/Packet-enhanced Optical Transport Network（OTN/POTN）technology,the problem of bearing frequency and time synchronization signal in OTN/POTN occurs.This paper proposes a test method based on 1588+SyncE synchronous network.Through the configuration of additional Optical Supervisory Channel（OSC）board and clock interface board in source OTN/POTN equipment,and the point by point method was used for the synchronous signal to be tested in a local loopback mode.This scheme solves the problem of measurement error due to remote testing,while removing the restriction of test source and test reference point,and can be tested at any node of the OTN/POTN system according to actual needs,reduce the cost of testing.关键词：OTN;synchronization;test methods
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发布时间： - 摘要：This paper proposes a new step size distribution method in variable step size Digital Back Propagation（DBP）algorithm.Several oblique lines are used to estimate the effective nonlinear coefficient which exponentially increases with the distance.Then a step size distribution is determined to ensure the difference of the slope between the oblique lines and the exponential curve is minimum.The optimal step size distribution is used in split-step Fourier method to compensate the nonlinear impairments.Simulation is implemented in a 3 200 km Daul-Polarization Quadrature Phase Shift Keying（DPQPSK）system with single channel rate of 25 Gbaud using the proposed step size distribution method.Simulation results show that the Q-value based on the step size distribution method is increased about 0.5 dB when compared with uniform step size distribution method.The proposed algorithm has larger tolerance on the nonlinear effects with low complexity.关键词：DBP algorithm;oblique lines method;split-step Fourier method
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发布时间： - 摘要：In order to realize the unified exchange of different types and sizes of business,the reference clocks used in the unified exchange technology are required to align and lock the phase of reference clocks.This article uses frame signal from the E1 interface to transmit the phase information of reference clocks.The information interaction of the frames among multiple devices and Field Programmable Gate Array（FPGA）are used to process the information,which can adjust the phase of clocks in the equipments.Simulation results show that the phase of reference clocks can be locked.This scheme is processed by hardware channel,which will not generate loss or misrepresentation of phase information,and can effectively solve the clock phase locking problem among devices.关键词：communication technology;SAR;phase locked;FPGA;encode the frame and decode the frame
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发布时间： - 摘要：The paper elaborate the key technology of 2.5 Gbit/s Burst Mode（BM）receiver for the 10 Gbit/s Passive Optical Network（XGPON）in the Optical Line Terminal（OLT）side.For the purpose of improving the performance of receiver,we apply an automatically method to adjust the frequency domain characteristics of the circuit,and design a receiving circuit which can establish the synchronization of the received signal in a very short time slot with high sensitivity.关键词：XGPON;BM-receiver;PON;time division multiple access
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发布时间： - 摘要：Optical Fiber Composite Overhead Ground Wire（OPGW）is a kind of widely used power cables,which has the function of overhead transmission line and optical fiber communication carrier.OPGW works outdoors for a long time,which will be affected by environmental factors and human factors.Monitoring and maintenance of OPGW is an important guarantee for the normal operation of the power system.In this paper,we first introduce the current development of the distributed optical fiber sensing technology based on Brillouin scattering in OPGW monitoring.Then the existing problems and future application prospect are also discussed.关键词：distributed optical fiber sensing;Brillouin scattering;OPGW;status monitoring
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发布时间： - 摘要：To further improve the communication capacity,a wavelength-mode division multiplexer/demultiplexer based on photonic crystals is proposed.Consisting of four combination resonator,four wavelength selective reflection cavities,and a pair of asymmetric parallel waveguides for mode conversion,the wavelength-mode division multiplexer/demultiplexer is realized by adjusting the radius and refractive index of the cavity as well as the width and the coupling length of the asymmetric parallel waveguide.Finite Difference Time Domain（FDTD）methods are used to simulating the performance of mode division multiplexer/demultiplexer.Numerical simulations show that the designed device has the potential for high-capacity Wavelength Division Multiplexing-Mode Division Multiplexer（WDM-MDM）optical communication systems with a low insertion loss<0.11 dB and a low mode crosstalk <-16 dB,which can meet the requirements of today’s large capacity optical communication system.关键词：photonic crystal;wavelength-mode division multiplexer/demultiplexer;FDTD method;combination resonator
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发布时间： - 摘要：Considering the difficulty in the switching of the filtering channel based on the traditional parallel micro-ring array,a new type of 2×2 router is designed using the spectral characteristics of coupling resonance to induce the transparency effect.First,the transmission matrix method is used to simulate and analyze the coherent interference and destructive interference conditions that produce Coupled Resonance Induced Transparency（CRIT）,and control the two CRIT channels.Then we design a new router and study the transmission coefficient and the micro-ring radius difference on the performance of the router.It is shown that the CRIT channel can be controlled flexibly by setting the coherence length.Larger router bandwidth can be achieved by increasing the micro-ring radius difference.The router can meet the requirements of stability,reliability,flexibility and anti-interference ability in the wavelength exchange and routing.关键词：CRIT;router;transfer matrix method;microring radius difference
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发布时间： - 摘要：Three-dimensional photonic devices can process multiple signals simultaneously in terms of multi-dimensional space division multiplexing,which increase the transmission capacity and improve the integrated density.In this paper,based on selfimage principle of 3D Multimode Interference（MMI）coupler,a 3D Beam Splitter（BS）with mode conversion is designed,which can be easily integrated.The 3D-BS with mode conversion can convert the input beam at the fundamental mode into three output beams at the fundamental mode and three output beams at the first-order mode.The length,width and height of the MMI are designed with polymer materials and optimized to be 3 398.17,50.00 and 29.37μm respectively.The simulation results show that the total transmission efficiency of the BS is 85.5%,and the transmission efficiency of the output fundamental mode is 28.9% with the maximum imbalance of 0.010 dB.The conversion efficiency of the output first-order mode is 56.6% and its maximum imbalance is 0.004 dB.关键词：integrated optics;multimode interference coupler;mode conversion;beam splitter
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发布时间： - 摘要：Slow light will play an important role for all optical network communication in the future.A design of out-of-plane slow light filter based on resonance induced transparency of zero contrast grating is proposed,which combines excellent transmission filtering function and slow light effect.The influences of etch depth and grating period on the slow light filtering performance is analyzed.It is noted that the change of the etching depth can significantly reduce the slow light filtering performance of the zero contrast grating due to the influence of the etching depth on the resonance mode constrained within the waveguide layer.However,the grating period mainly affects the phase matching between the incident light and the waveguide mode.Different grating periods can be used to select the different slow light filtering channels in the C band.In addition,the mode splitting effect of the oblique incidence condition is studied,and it is noted that the excitation of the non-degenerate resonant waveguide under the oblique incident condition leads to smaller the peak transmission an larger group refraction index.This research provides a new solution for the design of slow light devices.关键词：zero contrast grating;resonance induced transparent;out-of-plane;slow light filter
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发布时间： - 摘要：Based on controllability of the photonic crystal on reflection spectrum,the magnetic field and temperature sensing structure of one dimensional magnetic fluid infiltrated photonic crystal is designed.The reflection spectrum of the structure and the effects of the magnetic field and temperature to the reflection peak are numerically calculated using the full vector Finite Element Method（FEM）.Numerical simulation results show that the reflection peak is regularly moved with the magnetic field and temperature.The magnetic field and temperature sensitivity of the structure are respectively up to 136.4 pm/mT and-34 pm/℃ with a simple design and high linearity when N is 7 and the magnetic fluid thickness is 577.58 nm.关键词：one-dimensional photonic crystal;defect mode;magnetic liquid;magnetic field/temperature sensing
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发布时间： - 摘要：A two-stage optical amplification system is constructed by using double-clad Yb-doped fiber as the gain medium and multi-mode continuous pumped laser diode as the pump source.The circuit-direct modulated semiconductor laser is used as seed source to develop Master-Oscillator Power-Amplified（MOPA）fiberized pulsed fiber lasers.The output power characteristics of the fiber laser and gain characteristics of the secondary amplifier under different pulse width and repetition frequency are studied experimentally.A pulsed laser output with central wavelength of 1.06μm,peak power of 10.4 kW and maximum average power of 21.3 Wis obtained by adjusting the seed source under the condition that the primary pumped power is 2 W and secondary pumped power is 31 W.The maximum gain can reach 16.7 dB at 900 kHz repetition frequency.The experimental results show that the pulse width and repetition frequency are positively correlated with the laser output power.At high repetition frequency,the gain characteristics of optical amplifier are positively correlated with the pulse width.关键词：fiber laser;MOPA;pulsed laser;cascade amplifier
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发布时间： - 摘要：To meet the growing demand for traffic,ultra-dense network is one of the key technologies for the 5 Gnetwork.In recent years,the number of users and services increase rapidly in the ultra-dense network composed of Long Term Evolution（LTE）small base stations.The paper proposes an access control algorithm based on the cross-layer effective capacity,which can ensure the Quality of Service（QoS）of users and increase the throughput of the network.The algorithm considers the QoS requirements and the channel condition.It also defines the selection factor to determine the accessed LTE small base station.Therefore,load balance can be realized in each LTE small base station resulting in maximum effective capacity of ultra-dense network on the basis of ensuring the QoS of users.The simulation results show that compared with the traditional algorithm,the algorithm proposed in this paper can improve the system capacity significantly while guaranteeing the users’ QoS.关键词：ultra-dense network;access control;optimization selection factor;LTE small base station
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发布时间： - 摘要：The new generation of wireless communication has to meet the requirements in the Internet of Things with diversified business.The network slices can logically isolate the network,and each network works in a similar class of business.Therefore,the business differences between different slices is large,and the required resources are also different.In order to solve the problem of resource allocation among slices and provide better service for users,this paper proposes a fair proportion of resource allocation scheme based on Quality of Service（QoS）,which weighs the fairness and user’s requirements in each slice.The simulation results are compared with the proportional fairness and the maximum load-keeping ratio.The results show that the new algorithm can achieve higher user spectrum efficiency while guaranteeing the fairness.关键词：slice;resource allocation;5G;QoS
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发布时间： - 摘要：Narrow Band Internet of Things（NB-IoT）is a promising low-power Wide-Area Network（WAN）technology.Communicating a small amount of data over a long period of time is one of the goals in the NB-IoT,which is one of the key features in the IoT application.Some research groups have defined several NB-IoT standards,such as low power consumption,wide coverage,large capacity,and low cost.Compared with the conventional wireless communication protocol,NB-IoT spectrum bandwidth is only 180 kHz.Therefore,how to use resources or spectrum more effectively（i.e.,resource allocation and scheduling）is a key issue.In this paper,we first design the upper layer communication of the physical layer,especially the uplink scheduling.Then,we discuss the resource allocation of NB-IoT in the case of good delay.Finally,we discuss some open problems and their corresponding solutions,which ensure the reliability of signal transmission.关键词：NB-IoT;resource allocation;scheduling;performance
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发布时间： - 摘要：In order to reduce the light energy loss caused by the demultiplexing process of Red Green Blue Light Emitting Diode（RGB-LED）visible light communication system,an RGB-LED visible light communication system based on dichroic-demultiplexing method is designed.The principle and structure of dichroic-demultiplexing method are first introduced.Then the light energy loss in demultiplexing process is compared between dichroic-demultiplexing and the commonly used filter-demultiplexing.From the comparison results,dichroic-demultiplexing method can reduce the light energy loss caused by filtering,and improve the utilization of light sources.Then the communication system is simulated,and the simulation results show that under the same bit error rate,the system with dichroic-demultiplexing can effectively increase the transmission distance.关键词：visible light communication;RGB-LED;demultiplexing;dichroic-demultiplexing method
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发布时间： - 摘要：Based on the current hot issues on the visible light indoor positioning,we design a kind of visible light indoor localization method based on ultrasonic distance measurement after comparing several common visible light positioning method and combining with the existing conditions.Our proposed method has the advantages of high precision and low cost.This design uses the optical signal to achieve the synchronization with ultrasonic auxiliary ranging module.Then,light positioning algorithm based on multiple input multiple output is used to calculate the sensor location coordinates,which can effectively solve the issues of interferences in the transmitted light emitting diode and delay synchronization in received module.The error analysis and multiple debugging show that the sensor can correctly distinguish the region and coordinates of its location,and control the error in the request scope with good performance.关键词：visible light;indoor positioning;localization algorithm
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