Blind Feedforward Symbol-Timing Estimation With PSK Signals: A Constant-Modulus Approach

In this letter, the problem of blind symbol-timing estimation with M-ary phase-shift keying (M-PSK) signals is considered. An estimator exploiting the constant modulus (CM) property of M-PSK constellations and the structure of the received signal when the convolution of the transmitter's signaling pulse and the receiver filter satisfies the Nyquist criterion is proposed. Since the derived estimator, termed the CM estimator, requires a maximization with respect to a continuous variable, a closed-form approximate CM (ACM) algorithm, suitable for digital implementation, is proposed. Computer simulation results show that with small excess bandwidth factors, the derived ACM algorithm outperforms previously proposed algorithms at moderate and high signal-to-noise ratios