Joint time-frequency domain and code-aided carrier synchronization algorithm at low SNR

Since both high estimation accuracy and large synchronization range of code-aided carrier synchronization algorithms cannot be satisfied under low Signal-to-Noise Ratio (SNR) for short burst communication systems, a joint time-frequency domain and code-aided carrier synchronization algorithm is proposed. In the stage of the frequency coarse estimation, the proposed algorithm first takes advantage of pilot-aided approach to carry out time-frequency domain estimation based on rotational periodogram averaging (RPA) and time-domain correlation algorithms, and the coarse phase estimation is implemented with pilot-aided maximum likelihood (ML) algorithm. In the stage of the frequency fine estimation, the residual frequency offset is estimated based on code-aided time-domain correlation algorithm using the compensated after coarse estimation, and the fine phase estimation is done with code-aided ML algorithm. Simulation results show that the proposed algorithm can satisfy the requirements of frequency estimation range and root mean square error (RMSE). When the normalized frequency offset is in the range of (-0.5, 0.5), the performance degradation of the algorithm is within 0.1 dB compared with the ideal carrier synchronization at the cost of 6.1% pilot combining with decoder information.