Patent ID: 7839947

Claim:
A circuit for reducing the crest factor of a data symbol to be transmitted in a multi-carrier data transmission system, the data symbol being 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 being reserved which is not provided for data transmission, the circuit comprising: a transmit path configured to receive the data symbol; a model path arranged in parallel with a section of the transmit path the model path comprising: a model filter configured to receive at least periodically the data symbol in non-oversampled format, the non-oversampled data symbol exhibiting a non-flat PSD power spectrum; an analysis and evaluation circuit arranged following the model filter and configured to determine whether the time domain function of the non-oversampled data symbol, filtered by the model filter and exhibits within a predetermined time interval at least one maximum which exceeds a first threshold, and further configured to determine an associated position of the maximum within the time interval, and, by scaling and displacing a dirac-like sample function, to generate a correction function in dependence on the associated position and an amplitude of the maximum; and a combining device which is connected to the model path and the transmit path, the combining device configured to subtract the correction function from the non-oversampled data symbol on the transmit path; wherein the model path further comprises an oversampling device operably coupled to the model filter, and a bypass device configured to selectively bypass the oversampling device.