INITIALISIERUNG EINES MODEMS UND MODEM ZUR ÜBERTRAGUNG VON OFDM-DATEN

The present invention is concerned with an optimized efficiency of an Orthogonal Frequency Division Multiplex (OFDM) data transmission, in particular for power line communication. The length or duration of a guard interval or cyclic prefix in an OFDM symbol is selected from scratch at every start-up of a modem while initializing or preparing the OFDM data transmission. The length of the guard interval is given by the number L of samples in a time-discrete representation, and the value of L that is retained for the subsequent data transmission is selected from a plurality of pre-determined possibilities based on an evaluation of a channel quality of a communication channel including a physical line to which the modem is connected. Hence, the selected value of L depends on actual transmission conditions, and the optimization potential offered by a more flexible handling of the system parameters L and N is exploited in order to meet changing conditions on the physical line.