最新刊期
卷 ， 期 5 ， 2022
- 摘要：The optical transmission system based on all-band is considered to be one of the methods to effectively improve the transmission capacity of optical communication. In addition of the C and L bands, the using of other bands for transmission can fully tap the transmission potential of the existing optical fiber network and solve the bottleneck problem of large capacity communication network. The realization of its key technologies and systems is conducive to promoting the industrialization process of related technologies, which has broad economic benefits. This paper analyzes and discusses the current research status of multi-band optical transmission technology. And then as the focus, the performance difference of S、C and L band is studied by experiments. Based on the devices designed for C and L bands, the experiment of 40 km transmission system covering on S、C and L band is completed by using Polarization Division Multiplexed 16 Quadrature Amplitude Modulation (PDM-16QAM) modulation format, and the transmission capacity can reach 122.4 Tbit/s. The multi-band transmission capability of G. 652.D optical fiber is verified, which provicles an experimental basis for further research on multi-band optical transmission technology.关键词：all-band;single mode fiber;optical fiber communication
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发布时间：2023-01-29 - 摘要：In this paper, we study the deployment problem of distributed dedicated protection services in mobile edge computing. To minimize the total delay, we develop an Integer Linear Programming (ILP) model and efficient polling based heuristic algorithms. Simulation results show that the proposed double polling based algorithm can effectively reduce the total delay of all services and balance loads of the Mobile Edge Computing (MEC) servers.关键词：MEC;distributed services;dedicated protection;polling
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发布时间：2023-01-29 - 摘要：Multiple Input Multiple Output (MIMO) detection algorithm is used to compensate the Mode Dependent Loss (MDL) in Mode Division Multiplexing (MDM) optical fiber channel. The problem of MIMO detection algorithm is that the computational complexity is too high and the performance is degraded with a large number of modes. This paper proposes to apply Massive-MIMO detection algorithms to the fiber channel, The algorithms include Minimum Mean Square Error (MMSE) , Conjugate Gradient (CG) , Gauss Seidel (GS) , and Alternating Direction Method of multipliers based Infinity-Norm (ADMIN) , and Optimized Coordinate Descent based BOX constraint (OCDBOX) . The result shows that the OCDBOX has the best Bit Error Rate (BER) performance in MDL-impaired MDM optical fiber communication system while higher complexity. The ADMIN has the second best BER performance and lower computational complexity. Therefore, the ADMIN detection algorithm can represent a good candidate in the MDM system with MDL.关键词：MDM;MDL;massive MIMO detection algorithms;BER performance
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发布时间：2023-01-29 - 摘要：Aiming at the modulation problem of high energy efficiency and high sensitivity in the space laser communication system, the Differential Pulse Position Modulation (DPPM) format is studied and applied to the coherent optical communication system. The balance point is found in the system considering power consumption, Bit Error Ratio (BER) performance and bandwidth occupation through simulation and experiment. The experimental results show that in the direct modulation direct detection and coherent optical communication transmission systems, the optical power of the signal path required to reach the hard line is-36.5 and-60.0 dBm respectively when the same transmission channel and the same transmission rate of 1.25 Gbit/s DPPM signal is applied. The optical power margin of the coherent transmission system is increased by about 24 dB compared with the direct detection transmission system. In order to achieve the transmission goal of the hard judgment line, the optical power of the receiver for transmitting the DPPM signal at the rate of 3、6、12、24 Gbit/s needs to be about-49、-47、-42、-36 dBm respectively. It is demonstrated that higher sensitivity and lower BER can be obtained by using DPPM format/coherent detection.关键词：PPM;high sensitivity;coherent optical communication;space laser communication
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发布时间：2023-01-29 - 摘要：In order to mitigate the performance fading of Free-Space Optical (FSO) communication system caused by atmospheric turbulence, a multi-aperture receiving scheme based on digital coherent beam combining is used. Digital coherent beam combining relies on the digital phase alignment algorithm to align the different versions of signals in phase. In this paper, the statistical model of combining efficiency for digital phase alignment is derived in multi-aperture FSO receivers by considering the phase alignment errors at each receiving aperture. It can be expressed as a linear function of chi-square distribution by Satterthwaite approximation. Based on this statistical model, we derive the exact expressions of the mean, variance, and probability density function of the combining efficiency. The simulation results show that this model is valuable under the condition of the different number of aperture and signal-to-noise ratio combinations. Combining efficiency is also compared for Equal Gain Combining (EGC) diversity FSO systems with or without considering aperture selection.关键词：FSO;multi-aperture receiver;digital coherent combining;phase alignment
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发布时间：2023-01-29 - 摘要：As the single photon detection greatly improves the sensitivity of a traditional detector, it has enormous potentiality in distance measuring. Photon-counting laser ranging is able to extract the target's trajectory from large amounts of echo information in the case where prior information is unknown. This paper first provided the simulation of echo information produced by photon-counting laser ranging system, and then extracted the trajectory of the target through image processing. Comparing with the theoretical moving trajectory, the error is less than 5 m. Considering its advantages in short distance ranging, the photon-counting laser ranging system can be applied to the Beidou navigation system and solve its accuracy defects caused by environmental factors while cable patrolling.关键词：photon detection;RANSAC algorithm;target tracking;Beidou navigation system
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发布时间：2023-01-29 - 摘要：The visible light positioning system is the hot spot of current indoor positioning technology research. Aiming at the problem of inaccurate azimuth angle acquisition in single-lamp positioning system, this paper proposes a single Light Emitting Diode (LED) indoor positioning system based on marked LED. The scheme uses a single LED light with a non-flickering lamp bead as the transmitter to transmit information while realizing the lighting function. The smartphone acts as the receiver to capture images with bright and dark stripes, and obtain the azimuth angle by combining the geometric features of the projection and processing the algorithm. Then the position of the receiver is obtained by further calculation. The results show that in the actual application scenario, when the experimental heights are 1.75 and 1.45 m. The system can achieve average positioning errors of 6.9 and 6.5 cm, which verifies the feasibility and effectiveness of the scheme.关键词：single LED indoor positioning system;LED;geometric features;azimuth angle
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发布时间：2023-01-29 - 摘要：The traditional Optical Time Domain Reflectometry (OTDR) technology uses back Rayleigh scattering power for fiber detection. In transmission lines with optical amplifier, Erbium-Doped Fiber Amplifiers (EDFA) are mostly used to compensate for the loss of signal light and extend the transmission distance of the signal light. Since the EDFA amplifies the signal, it will generate spontaneous radiation noise, and the continuous accumulation of noise will rapidly decrease the signal-to-noise ratio measured by the OTDR. The paper mainly expounds the principle of Coherent Optical Time Domain Reflectometry (C-OTDR) technology. The detected signal optical power is concentrated to the intermediate frequency by the coherent detection method, and most of the noise can be filtered out by band-pass filtering the frequency signal. It can continuously extend the detection distance through the EDFA. We also propose to use the frequency shift keying method to eliminate the optical surge problem caused by the cascade of multi-stage repeaters in long-distance transmission of submarine cables. Through the development of self-developed coherent optical time domain reflectmeter, the actual test of C-OTDR technology in the simulated submarine cable multi-span transmission system has reached 3 000 km, which fully meets practical conditions.关键词：C-OTDR;submarine cable;repeater;dynamic detection range;acousto-optic modulator;frequency shift keying
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发布时间：2023-01-29 - 摘要：The optical network has become the most important way to carry power communications. To ensure its high reliability, operators need to detect the cables of the network periodically, which need to enter the substations. However, the large number and scattered location of substations bring challenges to the optical cable detection for the power communication optical network. This paper studies such multi-period optical cable detection problem of optical network in the context of power communication. With the objective of minimizing the total number of entered substations, we developed an Integer Linear Programming (ILP) model and a corresponding heuristic algorithm is also proposed. The simulation results show that the proposed heuristic algorithm can effectively reduce the total number of entered substations and perform close to the results of ILP model.关键词：power communication;optical network;cable detection;ILP model;heuristic algorithm
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发布时间：2023-01-29 - 摘要：In order to further strengthen the operation protection measures of the optical cable and realize real-time monitoring of the hidden danger of external force damage in the optical cable line area, this paper uses the principle of Rayleigh backscattering and coherent detection to design and construct an optical cable external damage event monitoring based on distributed optical fiber vibration sensing early warning system. Using Phase Sensitive Optical Time Domain Reflectometer (Φ-OTDR) technology, the optical fiber vibration signal is collected in real time. The key characteristics of vibration sensing are extracted, and the type of hidden danger is sent to the operation and maintenance staff to locate and warn the hidden danger of external force damage in real time. Field verification results show that the system can simultaneously detect and locate multiple vibration sources along the sensing fiber, and can identify various types of disturbance signals. The monitoring and early warning system has a complete system and a simple structure. The recognition rate of various construction signals is as high as 95%. It realizes double early warning of the type of external breakage and precise location, which can effectively prevent and stop external damage events and improve the work efficiency of anti-external breakage of optical cables.关键词：anti-breakage of optical cables;distributed optical fibers;optical fiber sensing;monitoring and early warning;hidden dangers of damage
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发布时间：2023-01-29 - 摘要：This paper develops an adaptive and extensible remote monitoring system for seafloor observatory network in the Laizhou Bay marine ranch to realize long-term, continuous and on-line monitoring for marine ranch environment. According to the demand of seafloor observatory network, the control model of the remote monitoring system is established in this paper. And this paper creatively designs the communication mechanism, standardized communication protocol and dynamic management algorithm convenient for the plug and play of a large number of devices in the seafloor observatory network. The algorithm of data quality control is also improved. The application demonstration data of the marine ranch in Laizhou Bay shows that the package loss rate of the system is only 1%, and the success rate of instruction execution is as high as 98%. When adding, deleting and modifying seafloor devices, the system can complete the mapping and analysis data within 2 minutes. At the same time, the data quality control algorithm can effectively eliminate outliers and reduce the error rate to 0.000 81%. The successful application example of Laizhou Bay Marine ranch proves the performance and applicability of the system. It shows that the relevant algorithms in this paper can also be used in other similar systems with adaptive requirements.关键词：seafloor observatory network;remote monitoring;data communication;device management;data quality control
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发布时间：2023-01-29 - 摘要：With the development of 5th Generation Mobile Communication Technology (5G) and the evolution of network architecture, the analysis and optimization of network coverage need to consider comprehensive factors, including not only the link budget of the base station antenna system, but also the geographical conditions and time characteristics of the area covered by the base station. Therefore, a more accurate network coverage optimization plan should be designed. This paper proposes an adaptive network coverage optimization algorithm based on Q-learning. The method first adopts a cellular network coverage prediction model based on data mining, which can predict the coverage situation of the access terminal through the configuration of the antenna of the cell, and verify the accuracy of the prediction based on real data. Then, a network coverage optimization algorithm based on Q-learning is proposed which modifies the action selection strategy of the agent in reinforcement learning process. According to the coverage of each cell, different optimization priorities are set. Combined with the greedy strategy, a cell and its antenna parameters are decided by the agent in each iteration. This method effectively reduces the probability of falling into a local optimum during the iteration process, and the method also has a good performance in reducing the convergence time of the optimization process. The simulation result shows that the algorithm can increase the network coverage by up to 20%.关键词：cellular network;coverage optimization;Q-learning;greedy strategy
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发布时间：2023-01-29 - 摘要：In response of the comprehensive popularization of Institute of Electrical and Electronics Engineers (IEEE) 802.11 in recent years, the rapid increase of Internet of Things (IoT) data has brought about problems such as high network transmission pressure, difficult data management, and high data security risks. Based on years of experience in WiFi wireless Access Point (AP) management and data warehouse implementation, this article expounds a construction method of wireless AP data warehouse based on anomaly identification and lossy compression. The results show that the abnormal identification and lossy compression of data with high repeatability of wireless AP can effectively solve the problems of high storage pressure and communication congestion in distributed data warehouses which caused by the excessive amount of repeated data of network equipment, and greatly reduce the overall cost when the company implement the data warehouse with IoT datas.关键词：wireless AP;abnormal data recognition;data warehouse;IOT
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发布时间：2023-01-29
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