最新刊期
卷 00 ， 期 6 ， 2021
- 摘要：In order to meet the increasing bandwidth demand, the future high speed, high capacity and low cost optical short and medium reach Direct Detection (DD) system becomes an inevitable trend. This paper first comprehensively reviews the advanced spectral efficient modulation formats in flexible transceiver and modulation methods which include the Double Side Band (DSB) and Single Side Band (SSB) methods to different transmission scenarios. In addition, considering the issue of different physical layer impairments, the details of the equalization schemes are reviewed. Finally, the extensions of future technology in the short and medium reach DD system are provided.关键词：short and medium reach;modulation formats;modulation methods;equalization schemes
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发布时间： - 摘要：Aiming at the problems of interference and energy consumption caused by the introduction of Device-to-Device (D2D) communication in the cellular system, this paper proposes to first combine D2D communication technology with full-duplex transmission technology to construct a full-duplex D2D communication link scenario. Then, the power control and resource allocation problems are solved respectively to improve the energy efficiency of full-duplex D2D communication link under the condition of satisfying the minimum rate requirement and the power threshold. Finally, the sequential quadratic programming algorithm is used to solve the power control problem. The proposed adaptive tabu search algorithm is used to solve the problem of optimal resource allocation. The results show that, compared with the existing algorithms, the proposed algorithm has effective search operator and perturbation mechanism, and can solve the energy efficiency optimization problem of full-duplex D2D communication links with lower computational complexity.关键词：full-duplex D2D communication;power control;adaptive tabu search algorithm;the optimization of energy efficiency
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发布时间： - 摘要：In view of the problem of low channel utilization in the Direct Current-biased Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) system for indoor Visible Light Communication (VLC), the channel and bit resources of the system are optimally allocated. This paper first introduces the signal transmitter model of the DCO-OFDM system and the calculation of the channel utilization of the system. Then we analyze the problem of channel resource allocation and bit resource allocation in sequence according to the two-step algorithm. Finally, we propose an adaptive dynamic resource allocation algorithm. The algorithm can flexibly allocate sub-channels according to the channel amplitude and frequency response, and adaptively select the highest order Quadrature Amplitude Modulation (QAM) modulation method for each channel to meet service quality requirements. The results show that, compared with the traditional fixed allocation algorithm, this adaptive resource allocation algorithm can significantly improve the channel utilization of indoor VLC DCO-OFDM system.关键词：indoor VLC;DCO-OFDM system;adaptive dynamic resource allocation algorithm;channel utilization
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发布时间： - 摘要：In order to solve the chaotic synchronization problem of two neuron models with different structures, the dynamical behaviours of Fitzhugh-Nagumo (FHN) neurons and Morris-Lecar (ML) neurons are studied respectively. Based on Lyapunov stability theory, a controller is designed by using the method of projection synchronization, and the chaotic synchronization of two neuron models with different structures is realized by the controller. The neural synchronization system is applied to chaotic secure communication, and the simulation results verifies its effectiveness and reliability in secure communication.关键词：neuronal model;chaotic synchronization;projection synchronization;secure communications
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发布时间： - 摘要：Aiming at the demand of high spectrum efficiency and low bit error rate of Wireless Optical Communication (WOC) technology, a joint modulation method of Pulse Amplitude Modulation (PAM) and Pulse Position Modulation (PPM) is proposed. The method makes full use of wireless communication bandwidth resources, which can improve transmission rate compared with traditional modulation technology. The system maps different amplitude pulses to specific lasers using Space Mapping (SM), and realizes multi-link layered transmission mapping relation. Being different from the traditional single-modulation methods, the joint modulation method uses the amplitude of the pulse and the change of the time slot position to transmit information through the coordination of the coding mechanism. The time slot position and amplitude information of each data pulse are sent and detected at the same time, using the joint modulation layered transmission technology. The experimental results demonstrate that the proposed method not only improves both spectral efficiency and transmission rate, but also improves the error performance. The experimental results provide a new technical method for the subsequent application research.关键词：WOC;SM;PAM;PPM;spectrum efficiency;bit error rate
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发布时间： -
Chaotic Spread Spectrum Technology for Optical Code Division Multiple Access Passive Optical Network
摘要：Aiming at the problem of capacity in Wavelength Division Multiplexing-Passive Optical Network (WDM-PON), Optical Code Division Multiple Access WDM-PON (OCDMA-WDM-PON) based on chaotic spread spectrum is proposed to expand the capacity and rate, ensuring the bandwidth requirement of optical fiber. The initial value sensitivity, auto-correlation and cross-correlation of Henon chaotic sequence as an address code are analyzed. The comparison of Bit Error Ratio (BER) performance between Henon chaotic sequence and Logistic chaotic sequence and Optical Orthogonal Code (OOC) are analyzed by simulation, which verifies the feasibility and superiority of chaotic sequence as address code in communication system. The experimental results show that the chaotic sequence as an address code has the advantages of good performance, large number of users, difficult to copy and easy to generate address code.关键词：PON;address code;chaotic spread spectrum;Henon mapping- 10
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发布时间： - 摘要：For laser products, safety certification is a mandatory requirement for international market access. For the standard application of certification, it is suitable for common laser product, but has less operability for optical fibre communication products. In order to make the evaluation of laser safety classification clear, this research is accomplished based on the general requirements of international laser safety standards and the application of optical fibre communication products and its characteristics. This research brings up a comprehensive discussion on measurement geometry, laser safety classification, automatic power reduction technology and safety design requirements. This research proposes a process and method for laser safety classification judgement. It also provides two verified test methods of automatic power reduction action time and the irradiance or radiant exposure during the maximum time interval. This research can provide a useful reference for laser safety design, classification, test and laser safety level certification of optical fibre communication products.关键词：laser safety;laser safety evaluation and classification;test method;optical fibre communication product;automatic power reduction
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发布时间： - 摘要：Ultra-low loss fiber is promising to support 400 Gbit/s or even 1 Tbit/s ultra-high data-rate optical transmission. Currently, there have been extensive studies on ultra-low loss fibers. In this paper, we make a comprehensive survey on the state of the art of ultra-low loss fiber technology from the aspects of fabrication, industrialization status, and application. Also, as a potential type of ultra-low loss fiber, hollow fiber is introduced. We wish to provide useful technical information to readers and promote the wide application of ultra-low loss fibers.关键词：ultra-low loss fiber;large effective area;pure silica core fiber;figure of merit;hollow fiber
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发布时间： - 摘要：Aiming at the problem of low spatial resolution of Optical Time Domain Reflectometer (OTDR) in long distance optical fiber link detection, this paper proposes a new scheme of Linear Frequency Modulation (LFM) -Golay OTDR. The scheme improves the dynamic range and spatial resolution of the OTDR by generating LFM signals to modulate optical signals and generating Golay sequence signals to modulate LFM optical signals. The experimental results show that the spatial resolution of the LFM-Golay OTDR can reach resolution of 0.22 m in the optical fiber link under test with a length of 200 km. Under the conditions of same setting parameters, the dynamic range is increased by about 15 dB compared with single pulse OTDR, and the dynamic range of LFM-Golay OTDR is about 6 dB higher than Golay OTDR and LFM OTDR.关键词：OTDR;LFM;Golay code;spatial resolution;dynamic range
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发布时间： - 摘要：In order to achieve tunable dual Fano resonance effect and high sensitivity refractive index sensing design, an H-shaped waveguide resonator is proposed to couple with the Metal-Dielectric-Metal (MDM) waveguide containing a single metal baffle in the middle part. The transmission spectra of the proposed structure have been calculated through the finite element method. It is demonstrated that double sharp and asymmetric transmittance peaks are emerged at the wavelengths around 810 and 1 350 nm respectively, which are generated by the double Fano resonances occurred vertically and horizontally in the H-shaped resonator with dimension of 300 nm×300 nm. Furthermore, the dependence of the transmission peaks on the structural parameters and refractive index of the H-shaped resonator have been discussed in detail. Finally, the double transmission peaks with the respective sensitivity of 750 and 1 360 nm/RIU have been achieved simultaneously in the proposed structure, which provide guidance for the design of nano-scale biosensors.关键词：surface plasmon polaritons;MDM waveguide;H-shaped resonator;Fano resonance
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发布时间： - 摘要：In order to reduce the crosstalk between the densely arranged polymer micro-nano fibers, this paper proposes to analyze the dependence of crosstalk on the intersection angle, diameter, separation, modal polarizations and wavelength of two intersecting polytrimethylene terephthalate micro-nano fibers using the Finite Difference Time Domain (FDTD) method. The results suggest that the crosstalk decreases with the increase of the intersection angle and separation. From the single-mode cut-off diameter, the crosstalk increases with decreasing diameter until reaching a maximum value, and then decreases afterward. Additionally, the crosstalk is lower in the Xdirection polarization and is smaller at the wavelength of 1 550 nm. These results provide good guidance and reference value for the construction of complex ultra-compact photonic devices and miniaturized integrated optical circuits.关键词：polymer micro-nano fiber;crosstalk;FDTD;polytrimethylene terephthalate
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发布时间： - 摘要：Considering the cost and large power consumption of high-resolution analog-to-digital converters in mmWave massive Multiple Input Multiple Output (MIMO) system, we develop a channel estimation algorithm with one-bit quantizer. Given the quantized received signal, the conditional expectation is first calculated to estimate the unquantized received signal. Based on the sparsity of mmWave channel in the angular domain, the column most correlative to the current residual is selected for least square estimation in each iteration. We also propose a solution to select multiple atoms in each iteration for the efficiency improvement. The simulation results show that the average normalized mean square error of the proposed algorithm and the running time of each iteration are 1/10 and 1/20 of the Expectation Maximization (EM) algorithm. It can be seen that the algorithm has improved performance and higher reliability, with certain practical value in the channel estimation application of mm-Wave large-scale MIMO systems.关键词：mmWave;one-bit quantizer;channel estimation;orthogonal matching pursuit
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发布时间： - 摘要：Least Square (LS) estimation method in Orthogonal Frequency Division Multiplexing (OFDM) system ignores the noise effect in the process of choosing the residual of atom update. In order to solve this issue, an improved Compressed Sampling Matching Pursuit (CoSaMP) algorithm is proposed by using the sparsity of the time-domain channel. Firstly, the initial channel estimation is performed by CoSaMP algorithm. Then, the Linear Minimum Mean Square Error (LMMSE) is used to reduce the noise, which improves the estimation accuracy. The simulation results show that the improved CoSaMP algorithm has better performance in mean square error and Bit Error Ratio (BER) estimation than traditional CoSaMP algorithm.关键词：OFDM;CoSaMP;channel estimate;LMMSE of compressed sensing
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