Blind Roll-Off Factor and Symbol Rate Estimation Using IFFT and Least Squares Estimator

To investigate the blind roll-off factor and symbol rate estimation of any linear digital modulation scheme, such as phase-shift keying (PSK) and quadrature amplitude modulation (QAM), an algorithm based on the inverse Fourier transform and the least squares estimator is proposed. First, the magnitude of the raised cosine pulse is provided by the inverse Fourier transform of the preprocessed power spectrum. The roll-off factor is then estimated based on the ratio of the second peak to the main peak of the magnitude. A coarse estimation of the symbol rate is extracted from the baseband shape. Based on the coarse estimation, a least squares estimator is used to improve the accuracy of the symbol rate estimation. Computer simulations show the efficiency of the proposed algorithm.