PAPR reduction in multi-carrier transmission system using selected scrambling

摘要

Input data 3 to be transmitted using a multi-carrier transmission system is duplicated. A first scrambling operation 20 is applied to the input data to produce first scrambled data and a second scrambling operation 21 is applied to the copy of the input data to produce second scrambled data. An inverse Fourier transform 25 is applied to the first and second scrambled data respectively and, based on the outputs of the inverse transform, either the first or second scrambled data is selected 26 for transmission. The selection considers the influence of the scrambling on the peak-to-average power ratio of the signal to be transmitted. Both the first and second scrambled data may be input into a single IFFT. This economy is achieved by using the real part of the complex transform to determine the transform of the first scrambled data and the imaginary part for the second scrambled data. The invention finds particular application in providing wire-line communication between a first unit situated at a predetermined depth of an oil well and a second unit situated at the surface of the well.