A fractionally-sampling based frequency offset enhanced blind estimator for non-circular transmissions

This paper deals with the problem of non-data-aided carrier frequency offset estimation of non-circular modulations transmitted through unknown frequency-selective channels. By exploiting the unconjugated cyclostationary statistics induced by oversampling the received waveform, an optimized carrier frequency offset estimator is proposed and its asymptotic (large sample) performance analyzed. In order for the proposed frequency estimator to achieve the minimum mean-square estimation error, it is shown that the oversampling rate need not be larger than twice the symbol rate. It is also shown that the proposed synchronizer is asymptotically jitter-free, admits a feedforward structure that may be implemented in digital form and is suitable for burst transmissions.