Research Of Carrier Synchronization Technique In Short-Burst Communication Systems Of PSK

The realms relying on the short-burst mode for communication(i.e. the military communication, the deep-space communication etc.) usually exist such a phenomenon: there is a relatively high-speed movement between both sides of communication, which will produce a large Doppler shift and thus cause a synchronous receiver to be unable to work normally and finally result in a serious decline in the quality of communication. In view of the problem, carrier synchronization techniques have been widely used. Besides, in order to improve the anti-noise ability of communication systems the modulation techniques have been developed and applied, and having become an indispensable part. Among them, the phase shift keying(PSK) is a common one, whose modulation's and demodulation's ways are simple so that it is easy for engineering implementations. So under the large Doppler shift, how to design and utilize good algorithms(i.e. with high precision and low complexity etc.) to realize an effective carrier synchronization in the short-burst PSK communications is a very meaningful issue.Based on research of development and application of the carrier synchronization techniques at home and abroad, firstly, we introduce some basic concepts about the carrier synchronization under an additive Gaussian white noise(AWGN) channel(including receiver models, synchronization criterions, synchronization modes and a performance lower bound), and discuss the characteristics of received signals with PSK modulation. Secondly, we study three data frame structures commonly used, i.e., Pre, Mid, PP. And for their limitations a general structure is proposed. By controlling several parameters of the proposed structure, it can better adapt to the short-burst communications. Thirdly, based on the general structure, we deduce the carrier-parameter estimation Cramer-Rao bound(CRB) applied to all synchronization modes, i.e., pure data-aided(DA) and non-data-aided(NDA), and joint DA-NDA. Through the CRB performance analysis and simulation for the pure DA and joint DA-NDA modes, we find that when ratios of data length to pilot length are minor, the pure DA mode should be selected, otherwise, the joint DA-NDA mode chosen. Meanwhile, we discuss a relationship between the CRB and the symmetry of the proposed structure and introduce a symmetric structure. If the frame structure is symmetric, carrier frequency offset estimation CRB and phase estimation CRB will be mutually decoupling. Then, according to the symmetric structure, we investigate the phase estimation of the pure modes, and put forward a phase estimation algorithm that can eliminate the effect of(residual) frequency offset, thus leading to a concept of pre/post phase estimators. Finally, we research the classifications and principles of the frequency offset estimation algorithms. According to the features of the algorithms, we give the algorithms' selection to the whole modes. At the same time two new algorithms for estimating the frequency offset are proposed based on the phase-increment method, namely, two-step and phase un-wrapping frequency offset estimation algorithms. Also, we deeply study the existing phase ambiguity problem and develop two solutions. Moreover, taking the first algorithm as an example, we discuss its best realization and parameter setting. Simulation result shows that the proposed algorithm has higher estimation accuracy and lower complexity than the other classical algorithms, which is more suitable for the short-burst communications.