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低压电力线通信技术是实现电网自动集抄的关键技术之一,但电力线作为信号传输通道有着复杂的传输特性和外在噪声干扰.为具体分析电力线信道特性对系统性能的影响,建立基于电力线通信标准中常用的正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)调制技术的通信系统模型.系统采用传输线理论计算电力信道的传输函数,同时利用米特尔顿A类噪声模型模拟信道噪声.重点分析了不同的信道噪声、网络拓扑结构、支路负载等因素对信道衰减和系统误比特率的影响.仿真结果表明了通信系统对于信道因素变化的敏感性,为将来低压宽带电力线通信系统设计提供了理论分析基础. 相似文献
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电力线通信技术是具有良好发展前景的一种宽带接入方式,但是噪声干扰严重,通信环境恶劣,正交频分复用是解决电力线通信问题的有效方法。文章运用Simulink建立了基于时间流的电力线通信信道模型和OFDM基带通信模型。通过对电力线信道模型下的采用OFDM的通信系统模型进行仿真验证,结果表明可以通过适当的编码和调制方式来提高系统的可靠性,并定性地分析了编码和误码率、调制方式和误码率之间的关系。 相似文献
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电力线信道的阻抗特性、信号衰减特性及噪声特性导致电力线通信的可靠性成为制约其广泛应用的重要因素。分析了低压配电网的物理拓扑结构和逻辑拓扑结构,结合我国低压集中抄表系统应用的工程特点,提出了一种基于图论生成树的电力线通信自动路由方法。该方法能够有效地建立起电力线通信网络路由,并根据信道变化动态地维护路由,保证了电力线网络的可靠性。实验测试表明了该路由方法的有效性、可靠性和实用性。 相似文献
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在低压电力线载波信道中,复杂的噪声特性是阻碍低电压电力线载波通信广泛应用的主要原因之一,因此,准确的噪声模型对于设计和优化电力线通信系统具有重要意义;为了得到更加准确的噪声模型,给出一种等效背景噪声和功率谱收敛算法;通过对多组拟合参数的求解,并以归一化理论和噪声特性为基础,实现功率谱收敛算法对准确噪声模型的搭建;通过低压电力线信道噪声分析,得出功率谱收敛算法能够收敛,功率谱收敛值0.535%,表明噪声模型可以准确地反映实际噪声特性,验证了功率谱收敛算法在噪声模型中应用的可行性。 相似文献
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在基于正交频分复用(Orthogonal frequency division multiplexing,OFDM)的可见光通信(Visible light communication, VLC)系统中,发光二极管(Light emitting diode,LED)的非线性特性是影响系统性能的一个重要因素。为了减小LED非线性的影响,将幅度-相移联合键控(Amplitude-phase shift keying, APSK)调制与OFDM技术相结合的传输方式引入可见光通信系统中。本文介绍了APSK调制的原理及其在基于OFDM调制的可见光通信系统中的应用,建立了基于APSK-OFDM调制的可见光通信系统模型,并与常用的基于正交幅度调制(Quadrature amplitude modulation, QAM)的OFDM系统性能进行了对比。仿真结果表明,在OFDM系统中,如果信道是理想的,QAM调制的性能要比APSK调制的性能好;但当考虑到LED的非线性特性时,后者的性能要明显优于前者。 相似文献
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Modern hospitals are beginning to adopt E-HEALTH as efficient complements to the traditional healthcare services. To support the E-HEALTH services, a locatable, radiation-free and high-capacity communication system is urgently needed in hospitals. Power line communication (PLC) systems can use the ubiquitous power line network to power the light-emitting diode (LED) lamps while serving as the backbone network for the indoor visible light communication (VLC) systems naturally. In this article, a hybrid broadband power line and visible light communication system with orthogonal frequency division multiplexing modulation is proposed for the indoor hospital applications, which gives a brand-new solution to replace the conventional wireless communication systems in hospitals. A general-purpose system model is provided and some basic techniques to enhance system performance are also investigated. Moreover, a feasible demonstration which supports over 48 Mbps data rate within a bandwidth of 8 MHz is implemented in the laboratory. 相似文献
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针对WFRFT系统难以适应复杂电磁环境及最优控制参数难以选取的问题,提出一种新型WFRFT认知通信系统构建方法。在传统WFRFT通信系统的基础上引入信号认知模块,完成电磁信号的采集及电磁环境中目标信号调制特征的识别。根据WFRFT信号调制特征裂变的特性,分析控制参数间的耦合作用机理,并设定优化控制参数的目标。将目标信号调制特征参数引入到WFRFT控制参数优化模型中,提出基于目标特征的WFRFT认知通信系统控制参数联合优化方法,并通过粒子群算法的迭代计算,选取最优控制参数集,针对最优参数的WFRFT认知通信系统,分别仿真计算高斯、莱斯、瑞利等典型信道条件下的误码率性能。实验结果表明,该方法可伪装信号调制特征,能有效提高通信信号的安全性,且在典型信道条件下的误码率性能较好,具有较好的抗干扰能力。 相似文献
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Recently, light emitting diode (LED) technology has been the focus of the information technology and green technology industries.The visible light communication (VLC) system uses LED technology for simultaneous illumination and data transmission. Therefore, the VLC system provides illumination to the user, which can provide both high quality multimedia services and various application services. The main concerns of VLC systems are illumination and bit error rate (BER) performance. Consequently, it is necessary to analyze the illumination control and method of transmitting multimedia data in the VLC system. In this paper, we propose a method to effectively transmit and Red, Green, Blue (RGB) three-color LED to video signal while providing dimming and color control from the VLC system. In the VLC system, LEDs can generate various colors of light by controlling the mixing ratio of each individual RGB color element. Thus, each RGB channel will have a different signal power, and each channel will have different performance. Therefore, we present a novel resource allocation using the RGB channel state information to allocate the multi-layers of video in the VLC system. The conventional system allocates the fixed channel to a scalable video coding (SVC) signal. However, the proposed system allocates a high priority to the SVC signal channel.As a result of computer simulation tests, the proposed system can improve the BER performance compared to the conventional system. 相似文献
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将Kolmogorov熵引入低压电力线信道特性的研究。通过计算不同条件下测得的电力线时间序列的Kolmogorov熵值,分析研究信道的混沌特征。主要结果有Kolmogorov熵值与电力网络的运行工况(地点、时间、负荷)呈正相关性,恒大于零,且趋于某一饱和值;同时,Kolmogorov熵受数据测量电路的通频带、采样间隔等参数影响。据此可推得如下结论:低压电力线信道具有混沌特征,短时可预测;Kolmogorov熵可作为描述低压电力线信道模型、估计信道特性的参数之一。 相似文献
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Impulsive noise is one of the main disturbances that damage the data transmission over power-line communication (PLC) systems. This paper presents an adaptive noise cancellation approach based on the adaptive neuro-fuzzy inference system (ANFIS) and a chaotic interleaver, namely ANC-CI-ANFIS scheme for impulsive noise estimation and suppression from the OFDM PLC channel. The ANFIS is based on a hybrid learning algorithm to identify parameters of Sugeno-type fuzzy inference system. Accordingly, fuzzy membership function parameters are trained using a combination of both least-square and back propagation gradient descent algorithms to emulate a given training data set. Furthermore, transmitted data are managed with a chaotic interleaver to secure data transmission and give more robustness against impulsive bursts. Simulation results are carried out on an OFDM PLC transmission chain compatible with the HomePlug AV standard under different impulsive noise scenarios. The results demonstrated the scheme's ability to detect and remove the impulsive noise from the PLC channel while keeping a high security level by using the chaotic interleaver. The major advantage of this system is its ease of implementation and faster convergence rate. 相似文献
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针对传统无人机空地信道模型不支持三维飞行轨迹和三维天线的问题,通过引入空间旋转矩阵和轨迹参数,提出了一种基于几何随机的无人机空地三维信道改进模型。该模型结合无人机对地通信场景的特殊性,利用时变布尔变量描述视距路径、地面反射径和散射路径的动态生灭过程。同时,文中还给出了二维角度、时延和功率等模型参数的时间演进算法,用于复现无人机对地信道的时变统计特性。数值仿真结果表明,改进模型输出的空时相关特性和多普勒功率谱均与理论值吻合,并且自相关特性与实际测量结果基本一致,该模型可应用于辅助无人机空地无线通信设备的方案优化、算法验证和性能评估等领域。 相似文献
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Communication-Aware Formation Control of AUVs With Model Uncertainty and Fading Channel via Integral Reinforcement Learning
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Wenqiang Cao Jing Yan Xian Yang Xiaoyuan Luo Xinping Guan 《IEEE/CAA Journal of Automatica Sinica》2023,10(1):159-176
Most formation approaches of autonomous underwater vehicles (AUVs) focus on the control techniques, ignoring the influence of underwater channel. This paper is concerned with a communication-aware formation issue for AUVs, subject to model uncertainty and fading channel. An integral reinforcement learning (IRL) based estimator is designed to calculate the probabilistic channel parameters, wherein the multivariate probabilistic collocation method with orthogonal fractional factorial design (M-PCM-OFFD) is employed to evaluate the uncertain channel measurements. With the estimated signal-to-noise ratio (SNR), we employ the IRL and M-PCM-OFFD to develop a saturated formation controller for AUVs, dealing with uncertain dynamics and current parameters. For the proposed formation approach, an integrated optimization solution is presented to make a balance between formation stability and communication efficiency. Main innovations lie in three aspects: 1) Construct an integrated communication and control optimization framework; 2) Design an IRL-based channel prediction estimator; 3) Develop an IRL-based formation controller with M-PCM-OFFD. Finally, simulation results show that the formation approach can avoid local optimum estimation, improve the channel efficiency, and relax the dependence of AUV model parameters. 相似文献
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B. R. Barricelli D. Gadia A. Rizzi D. L. R. Marini 《Behaviour & Information Technology》2016,35(11):879-896
ABSTRACTThe experience of immersive virtual reality (VR) can be considered as a communication process between human beings, mediated by computer systems, which uses visualisation and other sensory stimulation. In this paper, we analyse how VR characteristics can be explored using semiotic theory and, with methods of generative semiotics, we explore aspects of narrative and interaction in VR. We propose a semiotic analysis of VR communication focusing on syntax, semantics and pragmatics and considering also some principles of generative semiotics. The syntactic level is analysed as determined by the characteristics of the visual communication adopted. The semantic of VR is related to the functional model chosen to realise the virtual system. The pragmatic of VR is based on the human–computer interaction that changes the user's role. We explore how these aspects can be characterised in the context of VR communication design and what principles can be adopted for a VR application, and we present an analysis and a classification of the iconic signs that are being used in VR. Moreover, we present a framework that can be used to classify and describe different kinds of virtual reality systems and to better understand communication in VR, and we use it to classify eight popular systems for e-learning and collaboration. 相似文献
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The performance analysis of packet loss in end-to-end communication channel is the basis of adaptive end-to-end protocol design. However, existing analytical models of packet loss cannot provide quantitative information of lossy channel systems. In this paper, an analysis on balance state of end-to-end communication channel over probabilistic lossy communication networks (PLCN) is performed firstly. We then discuss the process of modeling end-to-end communication channel over PLCN using Quasi Birth–Death models (QBDs) in detail. Finally, some characteristics of end-to-end communication channel, such as the stability of channel and the performance of channel packet loss, are analyzed. The experimental results show that the proposed model can analyze quantitatively the stability of end-to-end communication channel and the packet loss probability during time interval [0,t]. The results in the work are helpful for designing adaptive end-to-end communication protocols. 相似文献