| Abstract |
Power Line Communications (PLC) is an area of research that has attracted much attention in the last few years. In fact, high-speed PLC opens up a new field for telecommunication services in domestic households without additional cabling. Although, the power line network has not been designed for transferring data, frequency ranges of some MHz are at the disposal for telecommunication purposes. Characteristics of a PLC channel such as frequency selective properties, varying impedance, considerable noise (impulsive), high attenuation and other effects, act as an obstacle to achieve a high-speed transmission with a conventional single-carrier approach. In order to achieve high data rates of some Mbps sophisticated and well designed digital transmission schemes and methods are necessary. In this thesis, the Orthogonal Frequency Division Multiplexing (OFDM) technique is considered as the modulation scheme for transmission over a power line channel. OFDM is a special case of multi-carrier transmission that manages to cope with the most distinct property of the power line channel. Furthermore, OFDM achieves a very efficient use of the allocated bandwidth possible. The first part of this thesis is a detailed study about OFDM modulation, as a transmission technique. In particular, the advantages and limitations of OFDM are presented, while the characteristics and the parameters that designate this method are investigated. Finally, a transmission model that simulate OFDM modulation scheme was designed and implemented in Simulink. The appropriate measurements were done and useful graphs and conclusions came up. In the second part of this work, properties and effects that characterize a power line are described and appropriate mathematical models to simulate them are adopted. These models were implemented in Simulink environment and measurements, graphs and conclusions were extracted.
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Μελέτη OFDM Διαμόρφωσης για μετάδοση Ψηφιακών Δεδομένων σε κανάλι Γραμμών Ενέργειας
