Research On Synchronization Technology Of Continuous Phase Modulation

With the development of digital communication, modulation techniques which have high spectrum efficiency and high power efficiency have been paid more attention. Continuous phase modulation which has constant envelope and memory characteristic possesses two kinds of good properties above. But its application is limited due to complex demodulation and difficult synchronization. Therefore, the research of synchronization technology of continuous phase modulation has great significance.With the background of vector signal analysis, focusing on continuous phase modulation, this paper studies synchronization technologies including timing synchronization, carrier frequency synchronization and carrier phase synchronization. The research of each key technology starts with a subclass of CPM, MSK-Type modulation. Then a synchronization scheme with high accuracy is provided for vector signal analysis, which is tested by the actual data. After that, the research object is expanded to the general type of continuous phase modulation.Firstly, the basic theory of CPM signals is introduced, including mathematical model and spectral characteristic. And the reasons of high frequency spectrum efficiency are investigated. Secondly, timing synchronization is discussed. Several timing error estimation algorithms are studied and simulated. Considering both estimation precision and stability, the improved MCM algorithm is chosen for MSK-Type modulation in the VSA. For CPM signals, a NDA feed-forward algorithm is discussed. To solve the problem of low accuracy, an improved algorithm using Newton iterative method is proposed. Thirdly, carrier frequency synchronization is studied. To realize larger estimation-range and higher precision, two-step synchronization mode is put forward, which means that delay-and-multiply method and maximum likelihood method are cascaded to complete coarse synchronization and fine synchronization. Then nonlinear transformation algorithm for CPM signal is proposed to achieve high-precision frequency synchronization. Finally, carrier phase synchronization is analyzed. One method based on decomposition of PAM and another method based on Taylor series expansion are studied and simulated. The latter with better performance is applied to MSK-Type signal in the VSA. Then 2P-Power algorithm is studied for CPM signal. For different modulation parameters, the algorithm has different performance.