EXPERIMENTAL ACTIVITY AND ANALYSIS OF PLC TECHNOLOGY IN VARIOUS SCENARIOS

Power line communications (PLCs) have become a key technology in the telecommunication world, both in terms of stand-alone technology or a technology that can complement other systems, e.g., radio communications. Since PLCs exploit the existing power delivery grid to convey data signals, the application scenarios are multiple. Historically, PLCs have been deployed in outdoor low voltage (< 1 kV) power distribution networks for the automatic metering and the management of the loads. Today, the evolution of the electrical grid toward an intelligent and smart grid that dynamically manages the generation, the distribution and the consumption of the power makes this technology still relevant in this scenario. Therefore, PLCs have raised significant interest in recent years for the possibility of delivering broadband Internet access and high speed services to homes and within the home. The increase in demand for such services has inspired the research activity in the in-home scenario, both toward the direction of the development of independent or integrated solutions, with respect to already existing technologies. Another application scenario that has not been deeply investigated yet is the in-vehicle one, which includes the in-car, in-plane and in-ship scenario. Since the power grid has not been designed for data communications, the transmission medium is hostile and exhibits high attenuation, multipath propagation and frequency selectivity, due to the presence of branches, discontinuities and unmatched loads. For the proper design of a power line communication (PLC) system, good knowledge of the grid characteristics in terms of propagation channel and disturbances is required. In this respect, we have performed experimental measurement campaigns in all the aforementioned scenarios. We aimed to investigate the grid characteristics from a telecommunication point of view. In this thesis, we present the results of our experimental activity. Firstly, we analyze the outdoor low voltage and industrial scenario. We have carried out a measurement campaign in an artificial network that can resemble either an outdoor low voltage power distribution network or an industrial or marine power system. We have focused on the channel frequency response, the line impedance and the background PLC noise, within the narrow band and the broad band frequency ranges. Then, we focus on the in-home scenario. In this context, we have studied the impact of the electrical devices (loads) connected to the power grid on the PLC medium characteristics and on the quality of the data communication. Their behavior has been investigated both in the time and frequency domain, in terms of load impedance and impulsive noise components that they inject into the network. Finally, we consider in-vehicle PLC, in particular the in-ship and in-car environment. Firstly, we summarize the results of a channel measurement campaign that we have carried out in a large cruise ship focusing on the low voltage power distribution network in the band 0-50 MHz. Thus, we present the results of an entire PLC noise and channel measurement campaign that we have performed in a compact electrical car

A Study on the Optimal Receiver Impedance for SNR Maximization in Broadband PLC

We consider the design of the front-end receiver for broadband power line communications. We focus on the design of the input impedance that maximizes the signal-to-noise ratio (SNR) at the receiver. We show that the amplitude, rather than the power, of the received signal is important for communication purposes. Furthermore, we show that the receiver impedance impacts the amplitude of the noise term. We focus on the background noise, and we propose a novel description of the noise experienced at the receiver port of a PLC network. We model the noise as the sum of four uncorrelated contributions, that is, the active, resistive, receiver, and coupled noise components. We study the optimal impedance design problem for real in-home grids that we assessed with experimental measurements. We describe the results of the measurement campaign, and we report the statistics of the optimal impedance. Hence, we study the best attainable performance when the optimal receiver impedance is deployed. We focus on the SNR and the maximum achievable rate, and we show that power matching is suboptimal with respect to the proposed impedance design approach