摘要
This paper presents a new fine time synchronization scheme for orthogonal time frequency space (OTFS) systems based on an embedded pilot structure in the delay-Doppler (DD) domain. The pilot is formed by a kernel sequence with both cyclic prefixing and postfixing, while the time synchronization scheme is equivalent to a three-stage process for estimating the timing offset (TO) in the delay dimension (θd) and the TO in the time dimension (θt). The first two stages operate in the delay-time domain, but the third stage operates in the DD domain. Stage 1 produces an initial estimate of θd by utilizing the periodicity of the cyclic extensions of the sequence pilot. Stage 2 identifies an estimate of θt by finding the first time bin along which there are sufficient pilot samples. Stage 3 further refines the estimate of θd by checking whether there exists another earlier possible delay estimate. The thresholding mechanisms for stages 2 and 3 are designed appropriately to make the TO estimation process work well. As compared with previous related methods, the proposed one achieves better performance in terms of the probability of perfect time synchronization and the peak-to-average power ratio. © 2026 IEEE.