Carrier Synchronizator in Nonbinary LDPC Coded Modulation Systems
This paper proposes carrier synchronizator in a nonbinary LDPC and high-order QAM system in order to solve some relevant problems (e.g. Doppler shift, spectrum efficiency etc.) in the satellite communication. The carrier synchronizator is divided into two parts: frequency estimator and phase estimator. The frequency estimator has two steps: single pilot block-based coarse frequency estimation and multiple pilot block-based fine frequency estimation performed by an autocorrelation (AC) operation and a cross-correlation (CC) operation, respectively. Through frequency compensation, the following phase estimator is carried out by the classical maximum likelihood (ML) criterion. Simulation results show that, for a (225, 173) nonbinary LDPC code over GF(16) with a 16-QAM systems, the proposed carrier synchronizator can eliminate large Doppler shift in the presence of random phase offset with low complexity.
KeywordsPilot-aided Nonbinary LDPC High-order QAM Carrier synchronization
This work was supported in part by the National Natural Science Foundation of China, by the 973 Program of China under Grants 61372074 and 91438101 and 2012CB316103, by the Fundamental Research Funds for the Central Universities (JBG160103, XJS15019), and by the China Postdoctoral Science Foundation funded project (2015M580819).
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