An Algorithm for Time-frequency Synchronization in OFDM based on CAZAC Sequences

To achieve time-frequency synchronization for Orthogonal Frequency Division Multiplexing (OFDM) systems, this paper proposes a synchronization algorithm based on Constant Amplitude Zero Autocorrelation (CAZAC) sequences. In this algorithm, a repetitive conjugate relationship preamble structure is first constructed based on the CAZAC sequence. Utilizing the conjugate properties of the CAZAC sequence, a timing metric function for the preamble structure can be derived, thereby achieving timing synchronization and obtaining an integer multiple of frequency offset estimation. Subsequently, the repetitiveness of the sequence is used to complete the estimation of the fractional frequency offset. Simulation results show that the proposed algorithm can achieve more accurate timing synchronization performance in both Gaussian channels and multipath fading channels. The frequency offset estimation performs better than other algorithms at low signal-to-noise ratios, while also having lower computational complexity.