Patent ID: 7286605

Claim:
Method for reducing a crest factor of a multi-tone-data signal which is transmitted in a predetermined transmission frequency band ΔF, wherein a multi-tone-correction signal is subtracted from said multi-tone-data signal, said multi-tone correction signal comprising a plurality of tone signals having frequencies outside said transmission frequency band ΔF, and the method comprising the following steps: (a) storing in a first memory at least one data symbol of a data symbol sequence, each data symbol comprising a predetermined number of data samples s(i) with index i, 0>=i>=(N−1), (b) comparing the amplitude of each data sample of said data symbol with a first threshold value to detect a data sample peak; (c) performing the following steps when a data sample peak is detected; (i) reading a multi-tone-correction signal comprising a corresponding number of correction data samples from a second memory; (ii) shifting cyclically the read correction data samples of the multi-tone correction signal so that the maximum of said correction data samples coincides with the detected data sample peak; (iii) scaling of the shifted correction data samples of the multi-tone-correction signal according to a predetermined spectrum mask; (iv) accumulating the scaled correction data samples of the multi-tone-correction signal in a third memory; (d) subtracting the accumulated correction data samples of the multi-tone-correction signal from the data samples of said data symbol.