Timing and Frequency Synchronization for OFDM Downlink Transmissions Using Zadoff-Chu Sequences

Orthogonal frequency division multiplexing (OFDM) technique has been widely adopted in wireless systems, but it is known for being sensitive to synchronization errors. In this paper, we present timing and frequency synchronization algorithms for OFDM downlink transmissions using Zadoff-Chu sequences. We show that the current timing synchronization method employing Zadoff-Chu sequences is sensitive to carrier frequency offsets. To reduce this sensitivity, we develop conditions for the selection of appropriate Zadoff-Chu sequences. We then design a training sequence and propose joint signal detection, timing, and carrier frequency offset estimation algorithms for OFDM downlink transmissions. We show that the proposed schemes simplify the overall synchronization architecture and improve the performance compared to the existing schemes in the literature.