Research Into The Carrier Synchronization Of He Continuous Phase Modulation Signals

Continuous phase modulation(CPM),as a kind of efficient modulation,was suitable for wireless,mobile communications and satellite communications.Compared with other modulations,CPM has constant envelope and rather good power efficiency characteristic,which makes CPM was researched more and more deeply in recent years.However,the use of CPM has been limited certainly due to receiver complexity and synchronization problems.Firstly, the paper introduces the continuous phase modulation technique, the history and the development of the CPM signals carrier synchronization and the principles of the CPM technique and carrier synchronization.Then, the paper focuses on the CPM signals carrier synchronization algorithms. For the problem that the ML carrier frequency synchronization algorithm converges slowly,the paper proposes that has been added to the coarse estimation before the ML frequency synchronization algorithm,has been simulated and the results show that the algorithm has a better convergence.Based on the ML estimation of carrier phase and symbol timing of the CPM signal on the basis of the Walsh functions decomposition, the ML Estimation algorithm based on nonsymmetric nonorthogonal exponential expansion has been proposed.The algorithm effectively improves the accuracy performance. Additionly, based on the correlative symbol timing synchronization algorithm on the basis of the orthogonal exponential expansion, the correlative symbol timing synchronization algorithm has been proposed based on the Zadoff-Chu synchronization sequences,the received signal is represented with nonsymmetric nonorthogonal exponential expansion.Computer simulations have been made and the results show that the method effectively improves the synchronization performance.