最新刊期
卷 ， 期 2 ， 2017
- 摘要：In this paper,we combine the Space Division Multiplexing（SDM）and Dense Wavelength Division Multiplexing（DWDM）technologies to experimentally demonstrate 560Tbit/s coherent optical dual-polarization DFT-s Orthogonal Frequency Division Multiplexing（OFDM）32Quadrature Amplitude Modulation（QAM）signal transmission over 10 km single-mode7 core fiber.The system uses 16 independent laser sources to generate 375 DWDM channels with 25 GHz grid.The channel capacity for single core is 85.91Tbit/s and the total channel capacity for the 7core fiber is 601.36Tbit/s.After excluding the 7%Forward Error Correction（FEC）which aiming at the threshold of 3.8×10-3,the net data rate is 562.02Tbit/s with spectral efficiency of 59.95bit/s/Hz.关键词：single-mode 7 core fiber;coherent optical OFDM;DWDM
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发布时间： - 摘要：We mainly compared the performance of Fast Fourier Transform（FFT）Orthogonal Frequency Division Multiplexing（OFDM）and Discrete Wavelet Transform（DWT）OFDM in Power Line Communication（PLC）.We first shown the PLC channel model.Then the Bit Error Rate（BER）and Peak-to-Average Power Ratio（PAPR）performances of DWT-OFDM and FFT-OFDM are analyzed with the interference of Additive White Gaussian Noise（AWGN）and Carrier Frequency Offset（CFO）.Throughout the simulation,DWT-OFDM is more appropriate to power line communications in the PLC system,which will make significant influence on the PLC in the future.关键词：OFDM;discrete wavelet transform;carrier frequency offset;power line communication
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发布时间： - 摘要：A novel rogue detection method is proposed to determine the ultimate result based on the validity of SD sampling over upstream optical signal.The OLT constructs a short timeslot and transmits it via an optical transceiver.Then,the OLT controls the optical transceiver to conduct a first SD sampling detection to the upstream optical signal according to the short timeslot to obtain a first detection result.Next,the OLT judges whether the upstream optical signal is valid according to the first detection result.If it is valid,the OLT constructs a long timeslot and transmits it via the optical transceiver,and controls the optical transceiver to conduct a second SD sampling detection to the upstream optical signal according to the long timeslot to obtain a second detection result.The OLT determines whether the current PON port is experiencing rogue behavior according to the second detection result.Compared to the common RSSI detection method,the proposed method has higher reliability and accuracy with the fact that no more fixed bandwidth will be occupied so as to assure the upstream bandwidth utilization as much as possible.关键词：passive optical network;optical line terminal;rogue detection;signal detection
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发布时间： - 摘要：In Visible Light Communication（VLC）system,the modulation bandwidth of Light Emitting Diode（LED）is limited by the transmit rate.In addition,the nonlinearity in the LED limits the overall throughput of the VLC system.In order to solve the problem of the nonlinearity in the LED in OFDM VLC with high peak-to-average power ratio,a one-bit sigma-delta modulator for nonlinear visible light communication systems is proposed.Studies show that the one-bit sigma-delta modulator can significantly improve spectral efficiency and the VLC system performance with OFDM modulation.关键词：VLC;LED;sigma-delta modulator;OFDM;nonlinear;high PAPR
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发布时间： - 摘要：In order to overcome the problem of limited bandwidth of LED devices used in a Visible Light Communication（VLC）system,a bandwidth efficiency scheme named DCO-CAP,employing Carrierless Amplitude and Phase（CAP）modulation,is proposed in this paper.In the proposed scheme,by utilizing orthogonal shaping filter bank and adding DC bias,a real and positive signal is transmitted in visible light link.Two kinds of Finite Impulse Response（FIR）of orthogonal shaping filter bank is proposed on the basis of Hilbert transform.The Bit Error Rate（BER）performance is derived for DCO-CAP system in VLC channel.The simulation results show that two types of filter bank have different capability in combating with the clipping noise jamming and identical capability in depressing channel noise jamming.It is proved that the optimal DC bias exists,which makes DCO-CAP system to obtain the best reliability performance.关键词：visible light link;DCO-CAP;Hilbert transform;DC bias;BER
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发布时间： - 摘要：Polar codes is a type of error-correction codes,which can reach the Shannon limit.Through years of study,many high-performance decoding algorithms have been proposed.Based on the traditional successive cancellation decoding algorithm,we study the principles and structure of the algorithm.In order to improve the performance of polar codes,we propose CRCSCL and lazy copy algorithms to reduce the complexity of the algorithm.The simulation results show that compared with the SC algorithm,the SCL algorithm can significantly improve decoding performance with lower complexity.关键词：polar codes;SC;SCL;lazy copy
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发布时间： - 摘要：The attenuation characteristics of seawater channel affect the laser signal’s transmission distance and receive power.In this paper,according to the coastal ocean of optical characteristics,we analyze the attenuation characteristics of the laser in seawater communications’ channel,and use Monte Carlo method to investigate the transmission process of the laser in seawater channel.Then,we obtain the simulation figures describing the relationship between the transmission distance and received power.We also use Gaussian function to fit the simulation results.In this way,we obtain a theoretical model to describe the relationship between the laser transmission distance and receive power at any position when seawater is impurity concentration.Therefore,we can quickly calculate the receiver power at any locations under certain distances,which provides a theoretical basis for the future design of underwater laser communication system.关键词：seawater channel;Monte Carlo simulation;Gaussian fitting;error of fitting
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发布时间： - 摘要：So far the formula for bit error rate of PPM cannot accurately analyze the performance of the PPM communication system when photon-counting detector arrays are used as receivers.In this paper,a revised representation formulation is derived based on Poisson channel.Firstly,we consider the situation when a photon is incident on a single photon-counting detector and an electrical is produced in response to that photon,and this detector can no long continue to probe the other photons in this time slot.Then according to the maximum likelihood detection,the synthetic signal of detector arrays output is manipulated into the formula.Finally,the MonteCarlo method is used to support our model and the results indicate that the modified expression is an accurate computation for the bit-error probability of M-ary PPM when the detector arrays are used.Furthermore,this equation can be used to optimize the number of detector arrays.关键词：space optical communication;PPM;photon counting detector array;poisson channel
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发布时间： - 摘要：The initial resource allocation for dynamic service requirement may lead to frequency spectrum fragment in Elastic Optical Networks（EON）,which will influence the allocation and resource efficiency of subsequent services.Spectrum fragment is one of the core problems for Routing and Spectrum Allocation（RSA）.This paper proposes an improved RSA algorithm for EON based on weights evaluation of spectrum fragments.This improved algorithm considers the Dispersion of Fragmentation（DF）as new parameter for evaluating spectrum fragments.Theoretical analysis and numerical simulation results show that compared with traditional RSA algorithm,the proposed algorithm can reduce the spectrum fragments degree and enhance the using rate of spectrum resources.关键词：EON;RSA;dispersion of fragment;resource utilization rate
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发布时间： - 摘要：The optical cable line is the lifeline of the optical fiber communication network.An optical cable remote monitoring system is designed and implemented in order to monitor the performance of the optical fiber transmission network in real time.Once the cable is interrupted,we could locate the fault point quickly.In this paper,we propose to use Standard Command for Program Instrument（SCPI）to control the Optical Time Domain Reflectometer（OTDR）through Synchronous Digital Hierarchy（SDH）optical transmission equipments Ethernet ports.The remote monitoring software is realized by LabVIEW programming.After the application of the optical cable monitoring system,the manpower and material resources used to deal with the failure will be reduced and the time to deal with the fault of the optical cable is also significantly reduced.关键词：optical cable monitoring;SDH;SCPI;OTDR
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发布时间： - 摘要：A low-temperature drawing-tower is designed and established to fabricate gradually tapered capillary by using polycarbonate perform.With inner-coatings of silver（Ag）and silver iodide（AgI）layers,flexible gradually tapered hollow waveguide is made and low loss property is obtained at the wavelength of 3.3μm.Transmission characteristics of the waveguide are investigated theoretically and experimentally.The influences of waveguide length,bending radius,and incident direction on the system property are investigated by experiment of methane gas detection.The results show that the coupling efficiency increases when the light incidence from the large end,and the detection limit and the sensitivity improves.The system has higher saturated absorbance when the light incidence from the small end.关键词：hollow waveguides;gas sensor;taper;flexible
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发布时间： - 摘要：In order to obtain the electric heating characteristics of three-core fiber composite ground faults,the finite element model of single phase ground fault is established by the electro-thermal coupling finite element method.We first establish a through copper conductors and lead alloy sheathed cable breakdown resistance in the insulating layer to simulate the occur of grounding fault.Then we use the finite element software SOLID69,SOLID90 to simulate the submarine cable conductor layer unit and nonconductor layer.We also combine the intelligence division and sweep division methods to mesh cable model.The temperature distribution of fault current distribution and cable body are obtained through simulation.Results show that the cable in the ground fault occurs with increasing temperature of copper conductor.Due to the ground fault,the fiber unit’s temperature within the layer also increases.We can find the fault location according to the highest point of light unit temperature.Our proposed method provides a theoretical basis for the electrical fault monitoring when using the distributed optical fiber sensing technology.关键词：three-core optical fiber composite submarine cable;the ground fault;optical fiber sensing technology;finite element modeling
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发布时间： - 摘要：A new type of graded-index ring fiber with 0.256 up-doping is proposed which can support 16 OAM modes.A FiniteElement Method（FEM）is used to calculate the effective indices of all the vector modes based on the measured index profile.The mode index difference can be improved to 6.656×10-3,which reduces the coupling among OAM modes.Furthermore,due to the gradual change of the fiber refractive index,the purity of the synthesized OAM light can attain 100%,and thus reduce the intrinsic mode crosstalk.关键词：orbital angular momentum;FEA;effective refractive index;mode crosstalk
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发布时间： - 摘要：With the development of high speed switching system,coherent Orthogonal-Frequency-Division-Multiplexing（OFDM）signal has been applied to All Optical Wavelength Conversion（AOWC）system.The AOWC of high speed polarization multiplexing OFDM signal based on parallel dual-pump is realized in Semiconductor Optical Amplifier（SOA）.The factors that affect the wavelength conversion efficiency are analyzed theoretically in terms of the laser phase noise and the SOA injection current.When the Optical Signal to Noise Ratio（OSNR）is 18 dBm,the Bit Error Rate（BER）of the converted signal is1.3×10-4.The 224Gbit/s coherent OFDM converted signal can be achieved without crosstalk.关键词：all-optical wavelength conversion;four-wave mixing;OFDM;polarization multiplexing;coherent detection
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发布时间： - 摘要：Optical attenuator plays an important role in solving the problem of channel power balance,optical fiber system index measurement,and power matching of all optical networks.In this paper,based on the Gaussian beam propagation and diffraction field theory analysis,the distribution of shutter based variable optical attenuator’s internal light field is studied.Based on the rectangle,triangle,round three types of shutter,the shutter based optical attenuator is experimentally investigated.The shutter based optical attenuator’s theory results and experimental results are compared.It is shown that the triangle shaped shutter optical attenuator has the best performance.关键词：optical fiber communication;VOA;shutter;attenuator
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发布时间： - 摘要：25Gbit/s SFP+ optical transceiver module is believed to be another more effective and practical solutions for the upgrading of current Ethernet and servers.In this paper,the standard development of 25 Gbit/s Ethernet and 32 GFC（Fiber Channel）are introduced,including the packaging of 25 Gbit/s optical module.The basic principle and structure diagram of25Gbit/s optical module are described.The technical scheme,interface index and devices and chips are also analyzed in detail,which provides a guidance for the design and implementation of 25Gbit/s optical transceiver.关键词：25 Gbit/s Ethernet;single mode optical fiber transmission;optical transceiver module
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发布时间： - 摘要：The use of a large number of passive devices in communication system makes passive intermodulation series connection problem becoming more and more common.In order to solve this problem,a simple model of two cascaded passive devices is established.In the mode of TE10,the nonlinear structure of metal-insulator-metal is characterized by Taylor series,where the effect of transmission line length on the input carrier signal phase is considered.We also analyze the variation of the passive intermodulation power with different length of transmission line and the input carrier phase differenceΔθ.The results show that the passive intermodulation power is different with the phase of input carrier signal in the two stage of the waveguide junction,and the cumulative value is between 0to 3dB.In addition,the transmission line phase length at the maximum and minimum cumulative value can be obtained by the phase differenceΔθ.Due to the interaction among the passive intermodulation frequency components,the intermodulation product types increase dramatically in waveguide.关键词：passive intermodulation;series connection;nonlinearity;transmission line
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发布时间： - 摘要：In recent years,the development of big data and cloud computing promotes the Ethernet switch to upgrade.In this trend,a transceiver with the SGMII is needed to be used between 100 Mbit/s switch and gigabit switch.SGMII is an interface of PHY and MAC.In this paper,in order to achieve direct communication between fast and gigabit switches,we propose to use a 100/1 000 Mbit/s PHY chip in the conventional 100Base-FX optical transceiver,which enable the 1 000 Mbit/s data from the MAC layer of gigabit switch convert to 100Mbit/s data and transmit out in the form of optical signal through the 100 BaseFX optical transceiver.关键词：Ethernet switch;SGMII;PHY;ESFP
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发布时间： - 摘要：In this paper,we present a new model for a nano-coupler between metal-insulator-metal plasmonic and dielectric slab waveguides.The model uses the resonance effect at the waveguide junction to improve the power coupling efficiency.The proposed model is demonstrated numerically by the Finite-Different Time-Domain（FDTD）method.The results indicate that when wavelength is 1.55μm the distance between resonator with junction is 230 nm and the depth is 420 nm,where the power coupling will be improved by 20%to 30%.关键词：metal-insulator-metal;waveguide junction;power coupling;optical resonator
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发布时间： - 摘要：The explosive growth of mobile data brings the problems such as base station overload,the scarcity of spectrum resources and so on.The traditional cellular network can not satisfy the requirement.In order to obtain the throughput and user density enhancement,heterogeneous cellular network become the inevitable choice.In this paper,we assume that SeNB is based on the coverage of S-MeNB and T-MeNB simultaneously,and based on the dual-connection technology in heterogeneous network.Then we design the process of S-MeNB switching to T-MeNB.In order to verify the success of the design of the dual connection handover process,we present a scheme of combining TTCN-3,which verifies the rationality and feasibility of the process design.关键词：dual connection;SeNB;S-MeNB;T-MeNB;handover
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发布时间： - 摘要：In order to improve the transmission performance of Bluetooth system in dynamic business,we analyze the impact of Bluetooth ACL（Asynchronous Connectionless）data packet on the throughput of the system under different Signal to Noise Ratio（SNR）,and propose a selection algorithm based on SNR linear predictive adaptive packet.The algorithm uses the Kalman prediction method to predict the SNR of future time slot based on time window,according to the estimated SNR to determine whether the system is required to switch the packet in the next time slot,and which packet types are more suitable for switching.Therefore,the throughput is optimal.The simulation results show that SNR prediction can respond to the channel changes in advance,and the overall optimal throughput is obtained under different channel quality.关键词：Bluetooth data transmission;signal-to-noise ratio;the eigenvalue decomposition;Kalman prediction
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发布时间： - 摘要：Aiming at effectively suppressing the selfish users in cooperative perception,a strategy and triggering policy of game theory with a reasonable utility function are proposed.The fusion center inhibit the selfish users effectively by controlling cognitive users’ benefits and prompt the cognitive users to choose favorable submission,who are eventually changed to the normal users.The cumulative benefits of each cognitive user determine the service priority provided from the fusion center.Finally,the MATLAB simulation results show that the overall performance of spectrum sensing system is improved by setting appropriate parameters of the relationship between there wards and punishments.关键词：cooperative spectrum sensing;policy of game theory;utility function;perceptual performance
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