INITIALIZATION OF AND MODEM FOR AN OFDM DATA TRANSMISSION

摘要

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 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 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 qualityofa 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.