SNR threshold indicator in data-aided frequency synchronization

The signal-to-noise ratio (SNR) threshold behavior is studied in the frame of data-aided carrier synchronization in additive white Gaussian noise. The closed form expression of the Chapman-Robbins bound, relative to the carrier frequency offset estimation is first established then used to derive an indicator of the SNR threshold. For a given sequence of pilot symbols, the threshold region is localized at the departure of the Chapman-Robbins bound from the Cramer-Rao bound. The data-aided maximum likelihood estimator is considered to examine the derived indicator usefulness.