Since the beginning of 20th century, the power line high voltage (HV) network has been exploited as a communications medium. Since no other communications network could offer such a geographic presence, reliability and cost effectiveness; electrical utilities core services, i.e., monitoring, operation management and limitation and removal of failures, were carried out by means of power line carrier (PLC) systems. Multicarrier modulation (MCM) begins to play an important role in HV communications.