【作者】 黄荣辉；

【导师】 周明天；

【作者基本信息】 电子科技大学 ， 计算机应用技术， 2002， 博士

【摘要】 高压电力线载波通信已有近百年的历史，它在电力调度话音通信、电力系统远动装置数据采集等方面取得了卓有成效的应用，但是利用一个台区的低压电力线建立Internet接入网是近几年来国际上刚刚兴起的技术。本文论述的电力线通信(Power Line Communications)计算机网络(以下简称PLC网络)是以低压电力线为通信介质实现数据传输或建立计算机网络的相关技术研究。由于低压电力线的普及程度比其他任何通信介质都广泛，研究电力线作为信息传输介质在技术和经济方面都有十分重要的意义。正因为如此，国际上本研究领域的专家克服重重技术难题，取得了令人充满希望的初步结果。我国是发展中国家，要赶超发达国家的信息化水平需要投入巨大的资金，而PLC网络提供了另一种可能的经济手段。尽快研究适合中国电力网环境的PLC网络技术正是本文的研究动机。 作为Internet接入网，PLC网络必须具备TCP/IP协议族中各分层协议的功能，然而，由于IP协议是屏蔽下层物理网络，实现异种网络互连的标准，因此，PLC网络的研究重点是开发适合电力线介质的物理层，以及支持IP协议的数据链路层。对于IP及以上各层可采用操作系统提供的通用网络功能。鉴于网络的物理层和MAC子层直接受通信介质传输特性的影响，并且电力线介质上存在大量的干扰，因此，PLC网络的关键技术是研究其物理层和MAC子层中干扰的特点、模型，以及克服干扰的方法和措施。本文对PLC网络中的几个关键技术问题进行了深入研究，主要的创新性工作包括： 给出PLC网络最佳数据帧长度模型。常规介质的计算机网络MAC层的帧长度与采用的介质访问控制方式有关。对于PLC网络，由于信道存在严重的非周期的异步脉冲干扰，其MAC层的帧长度不仅与采用的介质访问控制方式有关，而且与电力线上的脉冲干扰有关。目前国际上通常是按照常规介质计算机网络的方式确定PLC网络的帧长度，并没有深入研究脉冲干扰对帧长度的影响。本文论述了电力线信道上脉冲干扰的特性，运用概率论推导出存在脉冲干扰时求解数据帧长度的数学模型，并进行了仿真模拟验证。通过理论计算和仿真模拟，表明应用本文提出的方法可求解在给定脉冲干扰情况下的最佳数据帧长度。 提出了一种适合PLC网络特性的MAC协议框架。目前国际上注重研究PLC网络的载波频率、调制方式、信号编码等关键技术。而对于PLC网络的MAC协议，却通常采用修改的常规计算机网络的MAC协议。在国内，PLC网络技术研究的主要内容是物理层技术以及针对国外PLC芯片或部件的应用，目前还未见关于PLC网络MAC协议研究的文献。本文针对电力线的信道特征和调制方式，提出了一种适合PLC网络特点的MAC协议框架。该协议充分注意到采用OFDM调制方式后PLC网络的特性，借鉴了无线网络和HFC网络的诸多优点，从而减少了信道的竞争时间，并具有稳健性较强的主从结构。 推导出p比网络信道吞吐量的马尔可夫模型。传统局域网信道的基本特征是:采用单工工作方式，多用户同时争用一个信道，其MAC协议不考虑信道有特别的干扰。对于PLC网络信道，在采用OFDM调制方式并且信道存在脉冲干扰时，其信道的基本特征是:可采用双工工作方式，多用户同时争用多个子信道，必须考虑脉冲对信道的干扰。因此，对PLC网络信道吞吐量的分析，不能照搬常规局域网的分析方法。本文推导出PLC网络基于OFDM调制方式的信道吞吐量马尔可夫模型，运用该模型可从理论上分析数据帧长度、子信道数、脉冲干扰等参数对系统性能的影响。 给出一种p比网络MAC层协议性能数学分析模型。当PLC网络用于控制环境时，其用户数较少，连网时间也相对固定，因此，采用Pofhng方式的MAc协议是一种很好的选择。怎样研究这种方式的MAC协议性能?目前国外学者用仿真方法。本文给出一种分析Polhng方式MAC协议性能的数学模型，并对相关性能指标进行了分析，将分析结果与国外同类仿真研究进行了对比，结果表明所得到的协议性能数学分析结果与国外同类研究的仿真模型结果一致，并可通过调整模型参数比采用仿真方式更有效地分析协议性能。本文还结合中国电力线的信道特点进行了试算。 完成PLC网络技术实施。本文给出了PLC网络的一个实施实例。首先，给出了PLC网络技术实施的总体框架，以及包括LLC子层、MAC子层、PHY层功能分布、功能模块和接口说明的PLC网络芯片概要设计。然后，作者采用国外PLC芯片，组织参与开发了一个实际的PLC网络。其中探索性地使用拆拼和填充PLC网络数据帧方法，解决了PLC网络数据帧与以太网络数据帧的兼容性问题;设立IP地址到物理地址映射表和物理地址等待队列，提高了ARP包的解析响应速度。本文实例的开发结果是:实现了PLC网络文件共享、网络游戏、打印共享，并且通过以太网络访问Ihtemet的净速率达到56Kbps。更多还原

【Abstract】 Carrier communication over high voltage power line has been developing for near one hundred years. It has many applications for voice communication in power distribution, data collection from tele-control instrumentation, and so on. However, using power line within one transformer area to provide Internet access is a just recent development. Power Line Communications Networks (here after, "PLC Networks") addressed in this dissertation include technologies that use the low voltage power lines to carry data transmissions or establish a computer network. PLC Networks, due to the ubiquitous nature of Power lines, present a solution to providing wide reaching Internet access, which have important technological and economic implications. For this reason, power line communications have received international attention. A great many difficult problems have been overcome and the results are full of promise. As a developing country, China will have to lay out a large investment to catch up with other developed nations’ information infrastructure. PLC Networks present an economical alternative to approaches currently used by other nations. The purpose of this dissertation is to develop PLC Networks suitable for the Chinese power system.As Internet gateways, PLC Networks must have functions consistent with TCP/IP protocol family. However, as IP protocol is the standard to hide low layer physical networks and to realize interconnection among various networks, the research emphases of a PLC Network must be to provide the physical layer suitable for power line and the data link layer which supports the IP protocols. The functions of layers in or above the IP protocol layer can be obtained directly from a general operating system. On the other hand, because the physical layer and MAC sub-layer are directly affected by the transmission nature of the communication media, and there are much interferences on the communication media, the peculiarities of interferences, models, and measures for suppressing the interferences represent the key issues facing PLC Network research. Several of these key issues have been studied in this dissertation. The author’s main contributions presented in this dissertation include:Presentation of a model for the optimal frame length in a PLC Network. The length of the MAC layer frame in general-media computer networks is related to the method used in media access control. For a PLC network, the length of the MAC layer frame is associated not only with the method used in media access control but also with the nature of the interferences, since it suffers from a variety of interferenceswhich are non-periodic and asynchronous. At present, the main approaches to determine a frame length are borrowed from general-media computer networks, and thus no attention has been paid to the effect of the interferences. This dissertation discuss the nature of the impulsive interferences on the power line channels, and presents a model for finding a frame length and a simulated example using probability. By theoretical computation and simulation, it is shown that the optimum frame length in a given channel condition is easily obtained by the method proposed in this dissertation.Presenting a draw of the MAC protocol suitable for PLC Network. The research on carrier spectrum, modulation schemes and signal codes of PLC Networks has received much attention, while the MAC protocol of PLC Networks is usually adopted from general-media computer networks. In China, researchers in PLC Networks focus on the physical layer and implement solutions using oversea PLC chipsets and components. Up to now, no papers about MAC layer of PLC Networks have been published in China. This dissertation gives an outline of the MAC layer of PLC Networks which is suitable for the channel characteristics and modulation system, paying more attention to the peculiarity of channels modulated in OFDM and taking advantages of wireless networks and HFC networks. Therefore, there are less competition for channels and robust master-slave str更多还原