Adaptive Frequency Offset Estimator without in IDS-SS Systems Priori Signature Code Synchronization ,

An adaptive frequency offset estimator without priori signature code synchronization for DS-SS systems is proposed. First, we derive a maximum- likelihood (ML) estimation criterion, then parabola method is applied as adaptive estimator to solve the optimization problem, and the estimation range is widened by introducing forward-backward strategy. The analysis and simulation results show that the adaptive estimator is effective in low SNR, robust to frequency offset, and the estimation range amounts to 80 percents of symbol rate. .