Robust Time-Domain Fine Symbol Synchronization for OFDM-Based Packet Transmission Using CAZAC Preamble

Abstract

We propose an OFDM-based fine symbol synchronization scheme with robust threshold setting. Our proposed scheme applies a constant-amplitude zero auto-correlation (CAZAC) preamble with two identical halves, and implements the fine symbol timing in the time-domain (TD). By utilizing the proposed CAZAC preamble, the cross-correlation between received vector and the known preamble can generate a flat region on the left-hand side of the main-lobe, which provides a high resolution for fine symbol timing. Moreover, we analyze the downsides of the estimation range for threshold calculation in the Awoseyila's scheme, and then improve the threshold setting by employing an estimation range with robustness. The conducted simulation results show that our proposed scheme without signal-to-noise ratio (SNR) estimation has significant improvement as compared to the Awoseyila's scheme in high SNR region, and has asymptotical timing performance as compared to the Wang's scheme which requires the knowledge of SNR for optimal threshold setting.