Abstract: The method contains the following steps. First, in a MCM system with N sub-carriers, the baseband signal blocks Xj, j=1, 2, . . . ,B are supplemented with zeros and processed with LN-point IFFT, respectively, to obtain L-time oversampled time-domain signal blocks xj, j=1,2, . . . ,B. Then, xj undergoes Q Time Domain Circular Shifts or Frequency Domain Circular Shifts to obtain Q signal blocks {tilde over (x)}j(ij), ij=1, ?, Q. Subsequently, a B×B unitary transform is performed against ( x1, {tilde over (x)}2(i2), . . . , {tilde over (x)}B(iB)). After the unitary transform, for each (i2, . . . , iB) a combination having B time-domain signal blocks is obtained as follows: ({tilde over (y)}1(i2, . . . , iB), {tilde over (y)}2(i2, . . . , iB), . . . , {tilde over (y)}B(i2, . . . ,iB))=( x1, {tilde over (x)}2(i2), . . . , {tilde over (x)}B(iB)) cU where U is the B×B unitary matrix, and c is an arbitrary constant (c?0).

Abstract: The method contains the following steps. First, in a MCM system with N sub-carriers, the baseband signal blocks Xj, j=1, 2, . . . ,B are supplemented with zeros and processed with LN-point IFFT, respectively, to obtain L-time oversampled time-domain signal blocks xj, j=1,2, . . . ,B. Then, xj undergoes Q Time Domain Circular Shifts or Frequency Domain Circular Shifts to obtain Q signal blocks {tilde over (x)}j(ij), ij=1,?,Q. Subsequently, a B×B unitary transform is performed against ( x1,{tilde over (x)}2(i2), . . . ,{tilde over (x)}B(iB)). After the unitary transform, for each (i2, . . . ,iB) a combination having B time-domain signal blocks is obtained as follows: ({tilde over (y)}1(i2, . . . ,iB),{tilde over (y)}2(i2, . . . ,iB), . . . ,{tilde over (y)}B(i2, . . . ,iB)=( x1,{tilde over (x)}2(i2), . . . ,{tilde over (x)}B(iB)) cU where U is the B×B unitary matrix, and c is an arbitrary constant (c?0).

Abstract: A method for reducing the peak-to-average power ratio of the time-domain signal in a communication system using multi-carrier modulation is provided herein. The present invention is based on the method of recursive clipping and filtering to reduce the peak-to-average power ratio and out-of-band spectrum, but during the recursive process, the distortion of the multi-carrier modulated signal is controlled to be bounded within a specific region. In an additive white Gaussian noise channel with high signal-to-noise ratio, the present invention could achieve significantly lower error rate and the error floor phenomenon is almost completely removed. Therefore the power amplifier could be operated at higher average output power and a smaller range of linearity.