Fast iterative method for joint synchronization based on cyclic training sequence

Fast and robust time and frequency synchronization is crucial to wireless digital communications. Conventional synchronization methods usually compromise between estimation range and accuracy, so that multi-stage synchronization is usually required, which greatly limits the synchronization speed. Meanwhile, different non-ideal factors coexist in the received data, causing extra estimation errors, which would degrade synchronization performance. In this paper, an iterative method for joint synchronization based on the cyclically inserted training sequence (TS) is proposed for either continuous or burst block transmission systems. Timing and frequency offsets are jointly estimated and compensated, where the compensated data is used for further estimation. With iterative estimation and compensation, the estimation results for both timing and frequency offsets could asymptotically converge to the best estimation. Also, adjustment of estimation scheme is allowed in each iteration cycle, where estimators with large range are applied firstly to complete coarse estimation and compensation, and then estimators with high accuracy are performed to complete the synchronization. Simulations verify that the proposed iterative method can fulfill fast and robust synchronization with only two cyclic training sequences from adjacent blocks, while attaining high reliability and accuracy.