Multipath characterization of indoor power-line networks

The time- and frequency-varying behavior of an indoor power-line network is the result of variable impedance loads connected to its termination points. In fact, any signal transmitted through such a communications network is subject to time-varying multipath fading. In this paper, an analytical calculation method is presented, which can be used to determine the multipath components of any point-to-point channel in the indoor power-line environment. The method calculates all transmission characteristics of the network and, therefore, it can be exploited in the process of designing proper transmission algorithms for optimizing system performance. The proposed method is applied to an example network to demonstrate its usefulness in explaining the network's time-dependent behavior and in estimating channel parameters, such as subchannel bandwidth, multipath delay spread, fading conditions, etc.     

基于反相对称输入的多导体电力线通信

高频信号在多导体电力线上传输时会存在严重的线间串扰。造成接受端信号能量的损失和信号的混乱。本文以电力系统典型的线路结构为研究对象,分别采用几种空分复用的方式,在多条电力线上并行传输高频信号,并针对电力线路各相线间负载对称平衡（或不平衡）、线路终端阻抗匹配（或不匹配）等多种情形,进行了相应的计算和仿真。结果表明,采用反相对称输入的方式,能在一定程度上克服信号的线间串扰,有助于保持信号的相对完整性。     

Radio-frequency common-mode noise propagation model for power-line cable

Electromagnetic-interference (EMI) radiation from a power-line communications (PLC) network has been a major concern for the widespread use of broadband PLC technology. It is also well known that the dominant radiation mode of the PLC network is common mode (CM) by nature. Therefore, for electromagnetic-compatibility planning purposes, knowledge of the CM noise propagation path of the power line in the frequency range of 1 to 30 MHz is essential to provide insight of EMI radiation emitted by the power line. Based on a two-current-probe measurement approach, the CM noise propagation model for a three-wire power-line cable can be derived and represented by an equivalent two-wire CM transmission line. The equivalent CM noise propagation model allows us to predict the CM noise current on the power line with reasonable accuracy. The model will serve as a valuable tool in the future to identify effective ways to suppress EMI radiation from the PLC network.     

电力线扩频数传机的数字实现

讨论基于数字信号处理 (DSP)技术的 10kV电力线扩频数传机的实现方案 ,分析现场可编程逻辑阵列 (FPGA)产品作为DSP协处理器的优点。针对 10kV电力线的恶劣特性 ,充分利用数字实现及扩频技术的优越性 ,结合自适应均衡技术 ,实现 10kV电力线上的数据传输。     

An analog spread-spectrum interface for power-line data communication in home networking

Communication using power line as a medium of signal transmission offers a convenient and inexpensive solution for multimedia signal transmission and control applications in smart home networking. This work presents a novel analog spread-spectrum (SS) scheme for physical-layer interface in home networking. The proposed communication scheme uses a chaotic system to modulate the information signal for wideband transmission. The wideband spectral property of the transmitted chaotic signal adds robustness to the proposed scheme against the hostile power-line environment that is characterized by non-Gaussian noise and multipath propagation. By exploiting the ergodic property of chaotic signals, a simple noncoherent receiver is developed here. Not only does the proposed analog scheme demonstrate satisfactory communication performance, but it can also be implemented with simple hardware and low manufacturing cost, which is an important consideration for cost-effective home networking. The proposed noncoherent SS system does not involve quantization and complex synchronization process and, hence, it is more efficient in transmitting analog multimedia signals compared to the conventional SS system. Performance analyses illustrate the superior communication performance of the proposed analog SS system over the conventional SS scheme for multimedia signal transmission in a power-line home networking environment.     

宽带电力线通信技术应用浅谈

就电力线宽带接入网络的原理、优势进行了阐述。对宽带电力线通信（PLC）技术的国内外发展现状及存在的问题与争议进行了分析,并对宽带电力线通信技术的应用提出了一些建议。     

超宽带技术在电力线通信中的应用研究

目前电力线载波通信面临着传输速率、可靠性及电磁兼容等诸多方面的挑战。近年来,迅猛发展的超宽带无线通信技术为应对这些挑战提供了新的思路。文章首先简要介绍了超宽带通信技术,在分析低压电力线信道特性的基础上,用SystemV iew软件建立超宽带脉冲通信系统模型,并进行了原理性仿真;探讨将超宽带技术(UWB)应用于电力线高速通信的可行性,并就其中的关键和难点进行了归纳和阐述;最后展望了应用前景。     

Home network power-line communication signal processing based on wavelet packet analysis

Recent advances in signal processing methodologies have spawned the way for a high-speed home network power-line communication (PLC) system. In this paper, a novel signal processing method based on wavelet packet analysis is proposed to combat the adverse communication environment over power lines. A comparison research between wavelet transform and wavelet packet transform is presented. Since wavelet packet decomposition can provide more precise frequency resolution than wavelet decomposition, this paper proposes to use the wavelet packet analysis to deal with the highly polluted PLC communication signal. A hardware structure for the PLC system is presented as an experimental platform for sampling an actual communication signal. Simulation results based on these kinds of actual communication signals show the effectiveness of the proposed method.     

A loosely synchronous-coded OFDM system for power-line communications in home networks

High-speed data communication is critical for home networks to support the increasing needs of online multimedia entertainment. Power-line communication (PLC) presents a 'no new wires' solution for home networks. However, power line is a troublesome and noisy platform for home networks. And the traditional approach with PLC is interference-limited and has a small bandwidth. In this paper we propose a new scheme of orthogonal frequency-division multiplexing (OFDM) to provide better noise-limited PLC networks. This schema is based on loosely synchronous (LS) codes with very nice correlations. Construction criteria of LS codes used in the proposed system are provided and discussed. The capacity properties and spectral efficiency of LS coded OFDM systems over PLC channels are also studied in this paper. We show that the proposed LS coded OFDM can efficiently achieve the diversity provided by power line channels. Such a schema can be employed in PLC to increase data throughput, system capacity and spectral efficiency in home networks.     

基于OFDM电力线载波通信系统同步新方法

提出一种新的符号定时同步判决准则,并将其应用于低压电力线OFDM载波通信系统,实现了准确的符号同步.将所提出的方法及延迟相关法、改进延迟相关定时同步算法分别应用于实际低压电力线弥散通信网络中,对比分析结果表明采用提出的新定时同步准则算法克服了改进延迟相关法可能引起误判,判决阈值选择裕度小这一缺点,算法更稳定可靠.实际低压电力线信道实验网络测试表明,新判决准则不仅可以有效地进行OFDM系统准确的符号定时同步,且判决阈值选择裕度大,计算量较小.     

A nonlinear equalization method based on multilayer perceptron for OFDM power-line communication

A high-speed data-communication over low-voltage power line is currently an active field of broad application. Power-line communication (PLC), based on orthogonal frequency-division multiplexing (OFDM), is developing rapidly. OFDM with an appropriately selected guard interval is considered as one of the most effective ways to eliminate the intersymbol interference of high-rate signal transmission. However, it is unable to deal with the orthogonality degradation between the subchannels due to the time-variant characteristics of the multipath power-line channels, which are known as the interchannel interference problem. It is, therefore, necessary to introduce a nonlinear channel equalizer. In this paper, a multilayer perceptron scheme trained with a mean square error (MSE) criterion is proposed for the design of the nonlinear channel equalizer. The performances of the traditional linear equalizer and the proposed nonlinear one are compared. In order to evaluate the robustness of the proposed approach against the channel distortion, experimental measurements are made in a real PLC network. The effectiveness of the proposed approach is verified via the experiments on the test system.     

环网下电力线载波通信信道特性的影响因素分析

智能配电网除传统的树状拓扑结构外,还将出现环网、格状网等结构。建立具有这些特殊拓扑配电网的电力线信道模型并进行信道特性影响因素的分析是在智能配电网中应用电力线载波通信技术的必要前提和重要依据。首先提出了对不同网络拓扑具有通用性的基于信息节点的信道建模方法,在此基础上通过仿真分析了主干长度、分支长度、负载阻抗和分支个数等因素对环网拓扑下信道传输特性的影响规律,重点分析了这些影响因素对信号衰减的影响。通过实验验证了所得结果的正确性和有效性。所提出的分析方法和所得结论为设计智能配电网电力线载波通信的调制方法提供了必要的理论基础和技术手段。     

具有格状网的电力线载波通信信道特性的分析

智能配电网除传统的树状拓扑结构外,还将出现环网、格状网等结构。建立具有这些特殊拓扑配电网的电力线信道模型,并进行信道特性影响因素的分析是在智能配电网中应用电力线载波通信技术的必要前提和重要依据。通过基于信息节点的建模方法建立格状网拓扑的信道模型,并仿真分析前后主干长度、格网主干长度、分支长度、分支负载等因素对格网拓扑下信道传输特性的影响规律,重点分析了这些影响因素对信号衰减的影响。通过实验验证了所得结果的正确性和有效性。所提出的分析方法和所得结论为设计智能配电网电力线载波通信的调制方法提供了必要的理论基础和技术手段。     

电话、电脑和电力的“三网合一”概念与实现技术(三)——“三网合一”的应用研究步骤及展望

根据中国的实际情况 ,提出了实现“三网合一”的研究步骤 ,即 :优先发展利用电力线载波的配电自动化通信技术、开发电力市场用户侧交易结算的电力信息网络 ,初步实现“三网合一”。最后结合国外的最新技术报道 ,对电力线通信的前景进行了展望     

Maximum flow in probabilistic communication networks

The purpose of this paper is to provide a general approach for the problems of analysis and synthesis of probabilistic communication networks. The flows in the branches of a network may be interdependent random variables having any arbitrary distribution. A simple technique, based on the theory of best linear prediction, enables Monte Carlo simulation of such a network. The simulation results suggest that the distribution of the maximum flow (that can be established in the network) can be approximated by a normal distribution despite the inapplicability of the central limit theorem. The results of Monte Carlo simulation are consistent with those obtained through an alternative analytical procedure. The synthesis problem considered in this paper is that of finding the branch capacities of a network so that a given demand for flow (specified in terms of its mean and variance), between a pair of vertices of interest, is satisfied. A direct search method (to find out the optimal branch capacity vector) enables simultaneous consideration of the first two moments of the maximum flow as against the existing ones which consider only the first moment.     

电话、电脑和电力的"三网合一”概念与实现技术(三)--"三网合一”的应用研究步骤及展望

根据中国的实际情况,提出了实现"三网合一”的研究步骤,即:优先发展利用电力线载波的配电自动化通信技术、开发电力市场用户侧交易结算的电力信息网络,初步实现"三网合一”.最后结合国外的最新技术报道,对电力线通信的前景进行了展望.     

通信网络合法侦听研究

依据欧洲电信标准协会(ETSI)关于合法侦听的标准,并参考目前国内外关于合法侦听的研究现状,着重分析了合法侦听所涉及的参与方、侦听的基本流程、侦听的网络结构、侦听的转接接口、侦听点的选取等方面的问题;对以后的研究工作进行了展望.     

Continuum modeling of large networks

This paper is concerned with the modeling and simulation of extremely large networks. We derive a time‐dependent diffusion–convection partial differential equation, the solution of which captures the global characteristics of a stochastic network model. Continuum modeling provides a powerful way to deal with the number of components in large networks and opens up the use of highly sophisticated mathematical tools such as adaptive finite element methods. This, in turn, makes it possible to carry out—with reasonable computational burden even for very large systems—network performance evaluation and prototyping, network design, systematic parameter studies, and optimization of network characteristics. Copyright © 2007 John Wiley & Sons, Ltd.     

电力通信网安全风险计算模型

首先介绍了电力通信网风险三要素:资产、威胁和脆弱性的相关概念并举例进行说明,阐述了三者与风险之间的关系以及如何根据这三个要素计算风险值。为得到较为客观的风险计算结果,对现有的几种风险计算方法进行比较分析得出其优缺点。将风险三要素之间的相互关联性考虑到风险计算过程当中,提出了一种改进的电力通信网风险计算模型,并通过实例对其进行验证,该模型应用灵活,既可用于计算单因素的风险也适用于各因素间组合风险的计算。