INITIALIZATION OF AND MODEM FOR AN OFDM DATA TRANSMISSION

摘要

The present invention is concerned with an optimized efficiency of an Ort hogonal Frequency Division Multiplex (OFDM) data transmission, in particular for power line communication. The length or duration of aguard interval or cyclic prefix in an OFDM symbol is selected from scratchat everystart-up of a modem while initializing or preparing the OFDM data transmission. The leng th of the guard interval is given by the number L of samples in a time-discr ete representation, and the value of L that is retained for the subsequent d ata transmission is selected from a plurality of pre-determined possibilitie s based on an evaluation of a channel qualityofa communication channel inclu ding a physical line to which the modem is connected. Hence, the selected va lue of L depends on actual transmission conditions, and the optimization pot ential 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.