最新刊期
卷 ， 期 4 ， 2019
- 摘要：This paper makes a preliminary study on the visions and trends of the 6G mobile communication system. It believes that the breakthrough of basic information theory is the starting point of 6G development, and the development direction is to serve the individualized needs of human sustainable development. The paper preliminarily outlines the 6G’s total vision and the vision of each dimension. Then, we expand the actors from the three dimensions of "human-network-thing" to four dimensions of "human-network-object-environment", in the network. It is believed that future 6G will change the "environment" of the broad concept of human beings. We summarize the four new forms of 6G networks: interconnection of whomever, wherever, whenever and wkam. The development trend of 6G network performance should follow TRUST principle, including more than Tbit/s level bandwidth, extreme Reliability, Ubiquitous connectivity, Sub-millisecond delay, Terahertz spectrum, visible light communication and spectrum currently in use（including but not limited）. Finally, the paper expounds the representative key theoretical, technical and academic research results from different layer of the 6G network.关键词：6G;artificial intelligence;human-network-object-environment;network new forms;interconnection of whomever;interconnection of wherever;interconnection of whenever;interconnection of wkam;TRUST principle
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发布时间： - 摘要：To set threshold for multi-user signals overlapping with similar distance in two-dimensional optical coding access network link monitoring system, a link state recognition algorithm based on signal correlation is proposed. By analyzing the correlation between the normal signal and the detected signal, the link state is determined according to the self-defined correlation coefficient with compensation and the coding rules of the system. The simulation results show that the proposed algorithm can solve the problem of multi-link reflected signals overlapping with equal distance or similar distance. A 32-user experimental system with 3 equal-distance links is built. When one of the 3 equal-distance links is disconnected, the correlation coefficient is 0.626 1; when two of the 3 equal-distance links are disconnected, the correlation coefficients are 0.342 1 and 0.386 5, respectively, which are within the threshold interval. The self-defined correlation coefficient can effectively solve the problem of multi-user signals overlapping in the two-dimensional optical coding access network link monitoring system.关键词：access network link monitoring;multi-user signal superposition;signal correlation;self-defined correlation coefficient
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发布时间： - 摘要：In this paper, we present a heuristic algorithm based on graph-coloring and strategy of mobile station selecting serving cell to solve the wavelength-assignment problem which is a sub-problem of Routing and Wavelength Assignment（RWA） problem in Optical Transport Network（OTN）. We provide the process diagram, pseudo-code and designe the parameters to show the performance compared with other wavelength assignment algorithms. The experimental results show that the failure rate of wavelength assignment would reduce about 4%, and the increases of wavelength and regenerator are just 0.5%, which are under the constrain of wavelength-continuity and minimal number of wavelength and optical regenerators. This algorithm satisfies the application of network construct.关键词：OTN;wavelength-assignment algorithm;regeneration algorithm;cell select;RWA problem
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发布时间： - 摘要：Network sharing has become an important means for operators to reduce operating costs, speed up business listing and enhance brand competitiveness in the 4G stage. In the 5G phase, it is necessary to further explore the 5G multi-operator sharing co-modeling model. Firstly, this paper introduces the opportunities and challenges faced by 5G network sharing. On the basis of in-depth study on the standardization progress of 5G sharing in 3 GPP, the technical scheme of end-to-end 5G network sharing is given. At the same time, some difficulties of 5G sharing are analyzed, and the feasible deployment suggestions are given. Finally, this paper calculates the cost of indoor 5G single construction and co-construction with sharing, and the results show that co-construction and sharing have slightly more benefits.关键词：5G radio access network;network sharing;technical solutions
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发布时间： - 摘要：Considering the difficulty of receiving signals in traditional wireless networks where the radio frequency link is hard to reach, a method combining Radio over Fiber（RoF） technology as a wireless access mode with Orthogonal Frequency Division Multiplexing（OFDM） Passive Optical Network（PON） wired access network is adopted. An external modulation method based on Single Side Band（SSB） modulation mode is proposed to carry 60 GHz millimeter wave combined with reflective semiconductor light. The transmission platform is built combining wired and wireless two-way transmission based on Reflective Semiconductor Optical Amplifier（RSOA）. The theoretical analysis and experimental verification are completed based on this platform. Through simulation, the system performances of RSOA-based two-way wired and wireless hybrid access system are investigated at back-to-back and 20 km optical fiber transmission cases. The results show that when the transmitted signal adopts Quadrature Amplitude Modulation（QAM） formats, 4 QAM and 16 QAM signals adopt SSB modulation technique to carry millimeter wave through optical fiber transmission show best performance after 20 km transmission, which can meet the requirement of the network.关键词：OFDM;PON;RSOA;RoF
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发布时间： - 摘要：Polarization-maintaining fiber coil is the core component of polarization-maintaining Fiber Optic Gyroscope（FOG）. The second-order polarization crosstalk occurs within the polarization-maintaining fiber coil of the polarized light will produce many second order interference terms in the interference output end of the FOG, which may introduce phase error and affect the static parameters of the FOG, such as zero-bias stability. In this paper, we design a set of experimental fixture to produces high crosstalk points by exert precision pressure on the polarization-maintaining fiber coil. By controlling the two fixtures exert pressure in polarization-maintaining fibers depolarize length to produce a large number of second order crosstalk, the crosstalk points data is extracted for simulation calculation. Compared with the zero-bias stability data obtained from the actual test, the theoretical simulation value is consistent with the actual test value. As the pressure increases the intensity of the second-order crosstalk, zero bias stability of the FOG is worsening. The maximum intensity of second-order crosstalk produced by pressure is compared with that without pressure. The experimental results show that the zero bias stability of coil 1 is deteriorated from 0.006 3°/h to 0.015 1°/h, and zero bias stability of coil 2 is deteriorated from 0.012 5°/h to 0.017 1°/h.关键词：polarization-maintaining fiber coil;second-order polarization crosstalk;phase error;zero-bias stability
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发布时间： - 摘要：To meet the application requirements of high birefringence in optical fiber communication and sensing system, a new Photonic Crystal Fiber（PCF） is proposed in this paper.The designed structure is hexagonal, which is arranged by circular air holes. The inner cladding is designed as four elliptical air holes and two small round air holes. By applying full-vector finite-element method and changing the ellipticity and the size of small round air holes, we investigate the effective refractive index, high birefringence, nonlinear coefficient and dispersion characteristic of the fiber. The simulation results show that when the ellipticity is 0.5 and the diameter of small round hole is 0.8 μm, a high birefringence of 4.22×10-2,a high nonlinear coefficient of 109.65 km-1·W-1 and a dispersion value as low as-14 ps/（nm·km） can be obtained at 1 550 nm. The PCF proposed in this paper has high birefringence and high nonlinearity, which can be applied in the optical switch field and provide the theoretical basis for the research of optical communication and optical fiber sensing.关键词：PCF;finite element method;high birefringence;nonlinearity
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发布时间： - 摘要：In order to improve the coupling tolerance and coupling efficiency of Distributed Feedback（DFB） laser and single mode fiber, the coupling characteristics of DFB laser and single mode fiber are theoretically analyzed. A new dual lens coupling system of DFB laser and passive fiber is proposed. The coupling efficiency and coupling tolerance of the dual lens system are simulated by optical software. The traditional silicon or AlN optical coupling platform also needs to be integrated into the organic substrate with the laser driver circuit, which is not conducive to the integration of the system. This paper directly uses the organic substrate as the optical coupling platform, eliminating the need to re-integrate into the organic substrate, which makes the installation easier and the integration simpler. The stress analysis of the structure was carried out to simulate the warpage of BT organic materials, AlN ceramic materials and FR4 organic materials as substrate materials at the highest working temperature. Based on the simulation results, the dual lens system was fabricated and tested. The test results show that the coupling loss of the system is 4.9 dB, which indicates that this structure can provide reference for the coupling of DFB lasers and single-mode fibers.关键词：DFB laser;single mode fiber;coupling efficiency;organic substrate;dual lens
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发布时间： - 摘要：This paper presents a bilinear temperature compensator structure which based on the Arrayed Waveguide Grating（AWG） chips for the forward load-carrying technology of 5 G. The device composed of multiple drivers, which makes chips have different relative displacement and effective compensation in different temperature range. Temperature characteristic experiment is conducted to analyze the variation of central wavelength. The result shows that the wavelength offset during-40～ 85 ℃ can be achieved in 40 pm by using compensation device.In addition, the existing commercial devices are suitable for industrial environment and have achieved industrialization by measuring the insertion damage, offset and bandwidth of each channel before and after high temperature and high humidity reliability experiments.关键词：AWG;compensation device;industrial grade
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发布时间： - 摘要：The computational complexity of the sparse reconstruction based on Direction of Arrival（DoA） increases with the search range of angle dramatically. To address this issue, this paper proposes a joint DoA estimation method based on Fast Fourier Transform（FFT） and sparse reconstruction.Firstly, the method solves the problem that the DoA estimation method based on the classical Fourier transform that can only estimate the direction of the incoming wave within half of the angular range.Then, the improved method can estimate the rough range of the incoming wave direction over the entire range of angles which can be used to roughly estimate the angle.Moreover, the sparse reconstruction method is used to perform super-resolution angle estimation in the range, which greatly reduces the range of angle search and reduces the computational complexity.Simulation results show that the proposed method can not only reduce the computational complexity, but also has less angular error at low signal-to-noise ratio and few snapshot.关键词：DoA estimation;FFT;sparse reconstruction
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发布时间： - 摘要：In designing MAC protocols of Unmanned Aerial Vehicle Ad Hoc Networks（UANET）, control overheads and delay of data transmission have to be considered. Based on the existing multi-hop TDMA protocol of wireless Ad Hoc networks and the characteristics of UANET, an efficient and low delay multi-hop TDMA protocol of UANET is proposed. Our proposed method can reduce the network control overhead by efficient broadcasting using time slot allocation information based on topology information. It can also reduce the average network latency and improve success rate by the one hop node secondary allocation of data time slot and the multi-dimensional scheduling node time slot allocation sequence. The simulation results show that the proposed protocol outperforms the existing UAV MAC protocols when UAV nodes move faster and the topology changes frequently in terms of message average delay, success rate, control overhead and.关键词：UANET;TDMA protocol;topology information;secondary allocation;multi-dimensional scheduling
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发布时间： - 摘要：In order to solve the problem of transmission efficiency and flow control by sliding window mechanism in Mobile Ad Hoc Network（MANET）, a Variable Length Sliding Window Network Coding（VLSWNC） algorithm is proposed in this paper. The performance of this VLSWNC is studied using NS2 and evaluated in terms of the data throughput, packet transmission rate, and decoding delay when packet is transmitted. Simulations results show that the VLSWNC algorithm can significantly improve the network performance and reliability.关键词：MANET;Network Coding（NC）;sliding window;decoding
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发布时间： - 摘要：This paper presents a novel method to improve the Iterative Hard-Reliability（IHRB） based majority-logic decoding algorithm for Non-Binary Low-Density Parity-Check（NB-LDPC） codes. The method uses the most reliable symbols to calculate hard-reliability of other symbols in the decoding algorithm, which will not calculate the hard-reliability of poor reliable symbols and most reliable symbols. The proposed algorithm can provide effective trade-off between error performance and decoding iterative complexity compared to the non-binary majority-logic algorithm. For an NB-LDPC code over Galois field of 64 elements, the iterative complexity is reduced by about 51% compared with that of the conventional decoding algorithm.关键词：NB-LDPC codes;majority-logic decoding;truncated;hard-reliability
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