Abstract
The accurate timing and frequency synchronization is hard to obtain for space–time block codes (STBC) multiple input multiple output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems at low signal-to-noise ratio (SNR). In this paper, a new synchronization algorithm for STBC MIMO-OFDM system at low SNR is proposed. Firstly, a set of imaginary orthogonal complementary sequences with a set of imaginary complementary sequence sets and orthogonal matrix is constructed, and the proper length of the imaginary orthogonal complementary sequences is obtained by extending the sequences through transforming orthogonal matrix. Secondly, in order to improve the sequences’ auto-correlation and cross-correlation, the training sequences are constructed with their minus conjugates, and then superimposed on data signals. Finally, good synchronization is obtained by cross-correlation operation between the training sequences and data signals at the receiver. The integer frequency offset is estimated to be \(\varepsilon \in [ - N/4,N/4]\). Theoretical analysis and simulation prove that this synchronization algorithm achieves precise timing synchronization, wider frequency offset range and lower computational complexity at low SNR than conventional algorithm.








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Acknowledgments
This research is aided by the National Natural Science Foundation of China (No. 61310306022), and the Thousand Talents Program of Sichuan Province, Foundation for Leading Academic and Technological Experts of Sichuan Province, the College Innovation Team of Oil and Gas Exploration and Information Technology of Sichuan Province (No. 15TD008), the Training Program Foundation for the Talents by Southwest Petroleum University, and Signal Detector and Signal Processing Scientific Research and Innovation Team in Southwest Petroleum University (No. 2013XJZT007).
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Luo, R., Yang, J., He, G. et al. Synchronization Algorithm for STBC MIMO-OFDM System at Low SNR. Wireless Pers Commun 91, 237–253 (2016). https://doi.org/10.1007/s11277-016-3457-8
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DOI: https://doi.org/10.1007/s11277-016-3457-8