Análise de desempenho de sistema clustered-COFDM para a transmissão de dados via rede elétrica

Abstract

In this dissertation, is discussed and analyzed the use of coded- ortogonal frequency division multiplexing (COFDM) for broadband data transmission through outdoor low-voltage power electric network (Power Line Communications - PLC). Based on such discussion and analysis, the use of clustered-COFDM system is proposed and investigated to minimize the effects due to the presence of impulsive noise and the occurrence of spectral nulls in the frequency response of linear and time-invariant channels models of low-voltage electric networks, which are derived for data transmission applications. The main difference between COFDM and clustered-COFDM system is that the latter is a set of COFDM systems with a reduced number of tones that operates in parallel and in the same frequency band of operation of the COFDM system. A performance comparison between COFDM and clustered-COFDM systems under the same operation condition and when the transmitter makes use of partial and complete information of the channel is presented. Here, the term partial information means that the distance from the transmitter to the receiver is available. In this situation, the approachfor simulation is the same implemented to mutlicarrier systems applied to wireless communication. On the other hand, the term complete information about the channel is associated with the availability of each tone’s SNR (Signal to Noise Ratio) at the transmitter side. In this context, the approach for simulation is the one applied to multicarrier systems for wireline communications. The results obtained with simulations reveal that the clustered-COFDM offer lower BER (Bit Error Ratio) than the COFDM when partial information about the channel is available. If complete information of the channel is available, the clustered-COFDM allows lower BER and higher data transmission than the COFDM. Based on the simulation results, we conclude that the clustered-COFDM system is more appropriate that the COFDM one for PLC applications.