Patent ID: 7830783

Claim:
A method of reducing a crest factor of a data symbol to be transmitted in a multi-carrier data transmission system, in which the data symbol is a function of a plurality of signals provided within a predetermined time interval, each of the plurality of signals allocated to a carrier, each carrier occupying at least one frequency from a transmit data spectrum, at least one carrier having at least some reserved data carrying capacity not provided for data transmission, the method comprising: (a) performing an inverse Fourier transformation (IFFT) of the data symbol to be transmitted using a first IFFT module of a second signal path that receives the data symbol in parallel with a first signal path; (b) identifying peak values within a frame of the IFFT-transformed data symbol above a predetermined threshold using a first unit of the second signal path; (c) providing a sample correction function at an output of the first unit; (d) generating one or more vectors by allocating a scaling and phase rotation to the sample correction function according to the amplitude and position of the identified peak values using a second unit of the second signal path; (e) generating a correction signal in the frequency domain from a linear combination of the one or more vectors at an output of the second unit; (f) modifying the peak value of the data symbol to be transmitted by subtracting the correction signal at a combining device arranged to receive the data symbol on the first signal path and to receive the correction signal at an output of the second signal path; and (g) providing the modified data symbol in the time domain at an output of the combining device.