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This thesis starts with a general introduction to power-line communication. Then an existing application, communicating on a low-voltage grid, is investigated in order to obtain some knowledge of how the power line acts as a communication channel. Mời các bạn cùng tìm hiểu để nắm bắt nội dung thông tin tài liệu. | Abstract This thesis is about power-line communication over the low-voltage grid which has interested several researchers and utilities during the last decade trying to achieve higher bit-rates and more reliable communication over the power lines. The main advantage with power-line communication is the use of an existing infrastructure. Wires exist to every household connected to the power-line network. This thesis starts with a general introduction to power-line communication. Then an existing application communicating on a low-voltage grid is investigated in order to obtain some knowledge of how the power line acts as a communication channel. We also expose this system with a load consisting of a set of industrial machines to study the change in communication channel quality. After these large-scale measurements we measure some channel characteristics in the same grid. Measurements of the noise level and the attenuation up to 16 MHz are reported. The power-line communication channel can in general be modeled as having a timevarying frequency-dependent signal-to-noise ratio over the communication bandwidth. The effect of non-white Gaussian noise on different receiver structures is studied one ideal and one sub-optimal and the importance of diversity in frequency is illustrated when the set of transmitter waveforms is fixed. We investigate robust low-complexity modulation methods which are able to handle unknown phase and attenuation which simplifies the implementation of the receiver. Finally we describe a communication strategy that eventually could be used for information transfer over the power-line communication channel. In doing this we combine coding frequency diversity and the use of sub-channels similar to Orthogonal Frequency Division Multiplex . This is a flexible structure which can be upgraded and adapted to future needs. Preface v CHAPTER 1 Introduction 1 1.1 Power-Line Communications 1.2 Digital Communications 1.2.1 System Model 1.2.2 Bandwidth 1.2.3
