A Resistance Frequency Offset Synchronization Scheme Based on the Zadoff-Chu Conjugate Sequence

Zadoff-Chu (ZC) sequences have been used as synchronization sequences in many wireless communication systems because of their perfect correlation properties. However, almost all of these ideal characteristics are based on the assumption of zero carrier frequency offset (CFO). Under large frequency offset circumstances, the perfect autocorrelation property of ZC sequence is destroyed, where the main correlation peak is decreasing while the vice peak is increasing, consequently degrading the timing performance. In this paper, the autocorrelation of the ZC sequence and its conjugate sequence are investigated, and the symmetry between the modulus values of their autocorrelation functions is developed as well. Taking advantage of this symmetry, a novel training sequence composed of ZC sequence and ZC conjugate sequence is proposed. Also proposed is a corresponding synchronization scheme enabling robust timing synchronization based on the ZC sequence and ZC conjugate sequence at the receiver in the presence of large CFO.