最新刊期
卷 ， 期 1 ， 2018
- 摘要：To effectively reduce the cost of optical access network,a wavelength reused Mode-Division-Multiplexing（MDM）scheme for bidirectional optical access network with low mode-crosstalk Multiplexer/Demultiplexer（MUX/DEMUX）and Few Mode Fiber（FMF）is proposed.In downstream（DS）transmission,one of the spatial modes in FMF is used to transmit optical carrier while the others are used as DS signal channels.In upstream（US）transmission,the carrier is split to all the ONUs for US re-modulation.By utilizing mode MUX/DEMUX with low mode crosstalk and FMF,the carrier and each signal channel can be effectively separated.Moreover,to reduce the bidirectional Rayleigh backscattering noise,different optical sidebands for DS and US transmission are proposed.With the proposed scheme,symmetrical bidirectional 2×12.5 Gbit/s Quadrature Phase Shift Keying（QPSK）Orthogonal Frequency Division Multiplexing（OFDM）Intensity Modulation and Direct Detection（IMDD）transmission over 11.5 km 4-mode FMF is experimentally demonstrated.关键词：optical access network;wavelength reuse;MDM
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发布时间： - 摘要：The Coherent Optical Time Domain Reflectometer（COTDR）is an efficient tool to measure the state of submarine optical cable.However,it is difficult to detect the events on optical cable automatically due to the amplitude fluctuation on COTDR curve,which is caused by coherent Rayleigh noise and polarization noise.An efficient COTDR signal processing algorithm based on wavelet transform,linear dependent coefficients and moving averaging method is proposed.The amplitude fluctuation can be reduced and the curves obtained by the proposed algorithm is much smoother than traditional wavelet denoise algorithm.It is shown that almost all the events can be found in experiments.关键词：COTDR;wavelet;moving average;detect events;noise
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发布时间： - 摘要：In order to improve the bandwidth efficiency of optical communication system,a new multiplexing technology called Mapping Multiplexing（MM）technology is proposed.In the MM technology,multi-channel signal multiplexing is achieved by using dual-slot multi-amplitude signal mapped to multiplexing signal.This paper analyzes the principle of multiplexing and demultiplexing of MM technology,and uses 4-channel multiplexing as an case study to design MM multiplexer and demultiplexer by Matlab.By means of the combination of Optisystem and Matlab,the optical fiber transmission system is designed based on MM technology.The obtained eye diagram is very clear,which verifies the feasibility of the method.Compared with the same rate of NRZ signal and RZ signal,the bandwidth of MM signal is reduced by half and two-thirds.The proposed MM technology can not only effectively improve the system’s bandwidth efficiency,but also increase the dispersion tolerance.It has a wide range of applications in optical fiber communication system.关键词：mapping multiplexing technique;multiplexer;demultiplexer
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发布时间： - 摘要：Based on the transmission equipment of the current optical transmission/access network,a Point-to-Multipoint（P2 MP）network management scheme based on Hub-spoken structure is proposed.Digital wrapper overhead GCC0 is used as carrier monitoring and managing information channel,which can achieve low-loss,miniaturized terminal device monitoring and managing up to 8 remote node devices.In-band protocol and simple command protocol are also proposed in this paper to effectively transmit information of multiple remote node devices for monitoring and management.The remote node device is developed based on STM32.The software development framework and in-band implementation flow are introduced in detail.The experimental results show that the central office equipment can monitor and manage the multiple remote devices at the same time.关键词：Hub-spoken structure;P2MP;digital wrapper
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发布时间： - 摘要：When the Packet Transport Network（PTN）carries the power communication real-time service in the way of Time Division Multiplexing（TDM）,the parameter selection of de-jitter buffer becomes the key method to improve the service performance.In this paper,we first analyze the influence mechanism of de-jitter buffer parameters on TDM service performance.Then we design the numerical simulation algorithm to find the impact of buffer parameters on service performance.Finally,the optimization of de-jitter buffer parameters is realized by simulation.The results show that the optimized buffer length and packet size can effectively reduce the bit error rate and the transmission delay.关键词：de-jitter buffer;packet transport network;time division multiplexing;parameter optimization
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发布时间： - 摘要：Software upgrades are important in the communications products,which are also frequently used in engineering and network test scenarios.Using the single manual upgrade way,there are several problems as long overall upgrade time and low upgrade reliability.In order to reduce the impact of protocol stack software upgrades on business interruption,improve product reliability,and enable easy product maintenance,we require system package based upgrade function.Based on the distributed digital equipment upgrade program,all the single disks are started from the master download package,and all software are centralized stored and managed in the form of equipment package by the main control.The single disk no longer saves the single disk package.However,due to requirements of development and test,it need to retain the local start function.In the real business upgrade period,since the associated software package has been registered and verified,the time-consuming is short during the activation and upgrade period,which can minimize the impact on the business,reduce the risk of upgrade failures and operational cost.关键词：software upgrade;system package;distributed data communication equipment
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发布时间： - 摘要：In order to obtain the temperature change of the three-core fiber composite submarine cable overload operation condition,the finite element of three-core cable section and the section of the land sea model are established respectively.The feasibility of the model is verified by ANSYSY simulation.120%,140%,160%,180% and 200% of the carrying capacity are applied to the land and submarine cable model.It shows that the land cable model first reaches the highest ratio of submarine cable temperature 90 ℃.We also provide the emergency time in different load conditions.When the three-core cable overload in the lower case,the emergency time period in the submarine is longer than that in the landing area.The emergency time difference becomes smaller with the increase of load value.Our investigation provides a reference value for overload operation by the optical fiber sensing monitoring cable.关键词：three-core optical fiber composite submarine cable;overload;emergency time
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发布时间： - 摘要：This paper mainly analyzes the technology of high speed drawing from the aspects of fiber drawing furnace,fiber annealing,and fiber cooling.From the angle of the furnace temperature field and the airflow field,the distance between the diameter of the rod and the diameter of the center tube is explored.At the same time,the temperature and distance of the fiber holding furnace are explored and determined,which can effectively improve the optical fiber curl and reduce the broken rate.It is shown that the optical fiber cooling with He flow rate of 10 slm above can guarantee the diameter of the fiber coating and the microbend loss of the fiber.Through the exploration of the above parameters,we determine a set of ultra high speed drawing stable process,which can achieve a rapid increase in production and meet the market demand.关键词：drawing furnace;fiber annealing;cooling helium
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发布时间： - 摘要：Based on the leaky mode resonance effect and equivalent medium theory of the sub-wavelength grating,a one-dimensional suspension sub-wavelength grating is designed and analyzed by the Comsol Multiphysics software in 1 550 nm wavelength.The final parameters are determined by changing the width,height and period of the grating.The simulation results show that the polarization beam splitter has high reflectivity for the TE mode and high transmittance for TM mode in C band（1 5301 565 nm）under the condition of normal incidence.The extinction ratios of the splitter are over 20 dB and the transmissivity of the TM mode is higher than 98%.关键词：GaN;sub-wavelength grating;polarizing beam splitter;leaky mode resonance effect;equivalent medium theory
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发布时间： - 摘要：Recently,owing to the thriving business of internet applications,such as cloud computing and big data,communication traffic is growing rapidly.The fifth generation mobile communication technology will also further accelerate this trend.In order to satisfy the need of high capacity,high terminal density,lower power dissipation of data center interconnectivity and the need of metropolitan area network application,100 Gbit/s optical module has evolved from Centum Form-factor Pluggable（CFP）to CFP2 and further to Quad Small Form-factor Pluggable（QSFP）.The reduction in size and power dissipation of the optical module is a greater challenge to transmitter optical sub-assembly.Therefore,adopting hybrid-integrated packaging technology is the future direction for Transmitter Optical Sub-Assembly（TOSA）packaging,which can not only reduce the size of TOSA,but its power dissipation and cost as well.In this article,we introduce a QSFP28 100 Gbit/s hybrid-integrated Electroabsorption Modulated Laser（EML）TOSA,including its core technology,and show four eye diagrams that are up to the standard of 100 GBASE-LR4.Finally,a brief prediction of the future development of TOSA is made.关键词：lasers;optical system tolerance analysis;TOSA;EML
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发布时间： - 摘要：In order to solve the problems of oscillation on the top and side lobes of reflection spectrum for linear chirped grating,the influences of refractive index modulation depth,grating length,chirp coefficient on reflection spectrum are studied based on coupled mode theory,and the relationship between parameters and characteristics are deeply explored in this paper.A asymmetric apodized optimization method based on refractive index compensation is proposed.The effective apodization functions,compensation factor and optimal piecewise apodization ratio are also explored.Simulation results show that the peak shifts to the direction of longer wavelength,and the 3 dB bandwidths increase basically linear with L（5100 mm）,Δn(10-510-3)and C（0.010.2 nm/cm）,which can achieve 1.79,1.26,1.71 nm,respectively.The peak value increases with LandΔn,and decreases with C.There is a big shock at the top when Lis small.WhenΔnis large,obvious side lobes appear on both sides of the central spectrum.After applying the optimization algorithm,the linear region has increased,and the dispersion curve has been more stable.Compared to the traditional algorithm,the top of reflection spectrum is much more flat with no side lobe and no bandwidth reduction.The proposed optimization algorithm shows the better optical characteristics.关键词：chirped grating;reflectance spectrum;optimization;asymmetric;compensation factor
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发布时间： - 摘要：All-optical logic signal processing is a key technology in optical communication network,which has the potential to realize all-optical network.The all-optical numeric comparator is proposed based on Sum-Frequency Generation and DifferenceFrequency Generation（SFG+DFG）in quasi-phase-matched cascaded Periodically Poled Lithium Niobate（PPLN）waveguides.The waveforms are obtained by numerical calculation and simulation,and the performance of all-optical numeric comparator is analyzed by the parameters such as eye diagrams,pulse width,extinction ratio and peak power delay time.The results show that the cascaded waveguides can be used to deal with the all-optical signal.It can realize the corresponding logic function and guarantee the transmission quality of the signal,which expand the capability of PPLN waveguide on the all-optical logic signal processing.关键词：all-optical numeric comparator;cascaded PPLN waveguides;quasi-phase matching;SFG;DFG
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发布时间： - 摘要：With the increase of carrier power,the development trend of sophisticated communication equipment,the inherent non-linearity of passive components will cause serious Passive Inter-Mmodulation（PIM）interference,where the resulting impact can not be ignored.In view of this phenomenon,the microwave rectangular waveguide is taken as the research object,considering the main mechanism of PIM:quantum tunneling effect and hot electron emission effect.Based on the contact model of the waveguide flange Metal-Metal（MM）,a method of calculating the PIM power is proposed.The two non-linear effects are represented by the I-Vcharacteristics of the tunneling resistor Rnlc,using harmonic balance simulation and Matlab software for AC simulation.The non-linear current flowing through the tunneling resistor and the voltage drop at both ends and the PIM power in the waveguide connection are analyzed and calculated.The results show that the calculated PIM power varies with the contact pressure.The value of PIM power drops significantly at first with the increase of pressure.Then the value of PIM power declines slowly when further increasing the pressure and reaches a balanced state finally.关键词：passive inter-modulation;MM contact;non-linearity;PIM power
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发布时间： - 摘要：To solve the problems existing in the present probabilistic routing based on Bargaining Games,including redundant control packets exist in the exchange process of Summary Vector（SV）,redundancy exists in the messages interaction process,and unnecessary overhead from using special data structure to transmit matrix of delivery probability,an routing algorithm based on information piggybacked by SV and Low-overhead Routing based on Information Piggybacked by SV for opportunistic networks（LR-IPSV）is proposed.The LR-IPSV algorithm designs an improved exchange mechanism of SV and eliminate the redundant steps in current interaction mechanism.We also propose mechanism of piggybacking matrix of delivery probability with SV to reduce the control overhead and improve the network throughput.The simulation results show that the proposed LR-IPSV algorithm shows better performances than previous Probabilistic Routing Protocol using History of Encounters and Transitivity（PROPHET）algorithm and Game-theoretic approach to Stimulate Cooperation for Probabilistic routing（GSCP）algorithm in terms of overhead and throughput.关键词：opportunistic networks;Bargaining Game;routing;overhead
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发布时间： - 摘要：In recent years,people pay more and more attention to their own health and the physical health of their families.In view of this situation,an intelligent family health care system is designed in this paper.The system obtains blood pressure,body fat,blood sugar and other human physiological data by blood pressure monitor,body fat scale,blood glucose meter and other medical equipment regularly.Then the data is transmitted to the server through the gateway.The server feeds the abnormal situation back to users by big data processing.Users can log onto the healthy cloud platform,and find their healthy situation in real time,and then take the appropriate measures timely.In addition,there is a judgment on the elderly fall algorithm based on multi-sensor information to achieve real-time alarm for the elderly fall.A large number of tests and analysis show that the system can run stably and have certain guiding significances for the future application of intelligent medical research.关键词：intelligent medical;physiological data;gateway;healthy cloud platform
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发布时间： - 摘要：In the multi-network convergence of 5 G proposed by 3 GPP,the convergence of Long Term Evolution-Advanced（LTE-A）and Wireless Local Area Network（WLAN）has greatly improved the throughput and transmission rate of the system.The introduction of LTE-A WLAN Aggregation（LWA）is the centralized management of resources for multi-network integration and control,which is regarded as the basis of the architecture.Based on the radio resource management function and WLAN spectrum resources of LTE-A Pro system,the link aggregation of LTE-A and WLAN is designed to realize the establishment and switching functions in the LWA radio bearer.Finally,the terminal wireless resource management conformance test platform based on Test and Test Control Description Third Edition（TTCN-3）language is used to verify the design of the process,which proves the feasibility of the design.关键词：LWA bearer;LTE-A;WLAN;protocol consistency test
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发布时间： - 摘要：In order to reduce the influence of multipath dispersion effect on system performance and improve the anti-jamming capability of transmission channel,Separated Dual Pulse Position Modulation（SDPPM）scheme is used to complete the design of UV communication system.The pulse positions are separated from each other in SDPPM modulation symbols,which can effectively solve the inter-symbol interference problem.After the analysis of the SDPPM modulation symbol structure,SDPPM modulation and demodulation system is designed based on Field Programmable Gata Array（FPGA）.The frame synchronization of demodulation system is specifically described in detail.We use VHDL language in ISE 14.7 software to complete the code and Modelsim 10.1 afor the timing simulation,which further demonstrate the feasibility of the modulation scheme.关键词：SDPPM;UV communication;frame synchronization;modulation and demodulation
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发布时间： - 摘要：Due to the limitations of pilot pollution problems,efficient and highly accurate channel state information at the base station is critical to the potential benefits of implementing massive Multiple Input Multiple Output（MIMO）Orthogonal Frequency Division Multiplexing（OFDM）systems.It has recently been shown that Compressed Sensing（CS）techniques can solve pilot contamination problems.However,in the CS channel estimation algorithm,it is difficult to obtain the prior knowledge of channel sparseness directly.In order to solve this problem,an effective channel estimation method based on Bayesian Compressied Sensing（BCS）is proposed.The method uses sparse signal statistics as a priori knowledge to the multiuser multi-scale MIMO system uplinks.The simulation results show that the proposed method can reconstruct the original channel coefficients more effectively than the traditional channel estimation method.关键词：massive MIMO;Bayesian compressied sensing;channel estimation;pilot contamination
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发布时间： - 摘要：Aiming to the problem of interference management and resource allocation for mobile users in an ultra-dense network,a User Path based Resource Reservation（UPRR）algorithm is proposed in this paper.The scheme firstly takes the shortest path from the starting point to the end point as the metric to select an optimal path.In the selection process of the optimal path,this paper considers the condition that whether the blocks permit users pass through or not.Next the algorithm of resource reservation and resource reuse based on the optimal path is put forward,which firstly designs the steps of resource allocation and reservation,and then computes the resource reuse for all users in order to improve the utilization of spectrum resources.The simulation results show that the proposed algorithm can reduce the interference in the Femtocell Base Station（FBS）and improve the system performance on the basis of guaranteeing the low outage probability for mobile users.关键词：ultra-dense network;optimal path;resource reservation
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