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Initial Time Synchronization for OTFS
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AI
DOI：10.1109/TVT.2024.3435738.png)
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Abstract
En 中文
Initial time synchronization (ITS) is investigated for orthogonal time frequency space systems operating over the linear time-varying multipath channels exhibiting fractional delay and Doppler shifts on the delay-Doppler grid. Particularly, a comb-type preamble waveform carrying constant-amplitude preamble symbols is designed to meet the constraint of zero discrete ambiguity function and thereby facilitate accurate ITS. The receiver first measures the discrete cross-ambiguity values between the received signal and local discrete-frequency-shifted comb-type preamble signals for discrete time shifts sequentially. With the measured discrete cross-ambiguity values, the preamble-comb-based ITS approach using sequential threshold comparison and select-the-largest identification is then developed to estimate the start time of a received preamble frame on the leading channel path. Preamble-comb-based coarse and fine ITS systems are investigated to operate over a wide timing acquisition range (TAR) under the influence of data self-interference (DSI) and over an adjustable narrow DSI-free TAR, respectively. When the channel exhibits a strong leading path and wide ranges of fractional Doppler shifts, the preamble-comb-based ITS systems are shown to outperform several conventional ITS systems significantly in estimation robustness and accuracy for sufficiently high preamble signal-to-noise power ratios.
Keywords:
Delays
Symbols
Receivers
OFDM
Accuracy
Time-frequency analysis
Doppler shift
Comb-type preamble waveform
initial time synchronization
linear time-varying multipath channel
orthogonal time frequency space
Journal
IF:
7.1
Papers:
1.8W
Citations:
6.6W
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Cited Papers
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