Comparison between digital phase recovery techniques in the presence of a frequency shift

Analyzes the behaviour of different digital phase recovery techniques in the presence of a frequency offset. Comparison is given in terms of phase error variance and acquisition time. The authors show that the sliding block version of the expectation maximization estimator algorithm [Qin, 1993] for QPSK phase recovery, in the presence of non-negligible frequency errors (ΔfT≈10^-3), gives results which are comparable or even better than those of the Viterbi and Viterbi non-decision aided nonlinear phase estimator [Viterbi and Viterbi, 1983]