Research On The Synchronization Technology In The Continuous Phase Modulation System

The Continuous Phase Modulation(CPM)system has the advantage of high spectrum utilization,constant envelope,and huge application potential in modern wireless communication systems.However,the receiver design of the current CPM system is very complicated.Especially,it is difficult to realize the synchronization of the received signal,which results in lots of restrictions on the actual application of the CPM system.In order to solve this problem,this thesis conducts theoretical research and algorithm improvement on the receiver synchronization algorithm of the CPM signal.First of all,this thesis gives the basic definition of the CPM signal and analyzes the time-frequency characteristics of the signal for the CPM signal description model.Then,the synchronization model of CPM signal is built.By analyzing the theoretical limit of synchronization estimation and analyzing the simulation of the various synchronization parameters on the system performance,the basic requirements of the CPM synchronization waveform design are obtained.Then,the CPM waveform design method in the wireless system is given.Secondly,this thesis designs the algorithms of the frequency estimation in the different communication scenarios according to the carrier synchronization requirements.Under the fixed frequency offset condition,the direct discrete Fourier transform(DFT)frequency estimation algorithm of the CPM signal and the traditional Fitz algorithm,i.e.,Luise & Reggiannini(L&R)algorithm and Mengali & Morelli(M&M)synchronization algorithm,are analyzed and simulated.Then,a frequency offset estimation algorithm based on dual-pilot is proposed,which greatly improves the accuracy of frequency parameter estimation.To solve the problem that the algorithms mentioned above cannot balance the estimation range and the estimation accuracy,the thesis proposes a step-by-step estimation algorithm.By reasonably selecting the estimation algorithm and the parameter configuration of each step,the step-by-step synchronization algorithm has the advantages of large estimation range and high accuracy.Under the condition of the high dynamic frequency offset,this thesis proposes a delay-autocorrelation algorithm for the dynamic frequency offset estimation.A dynamic frequency offset estimation algorithm based on Dual-Pilot assistance is proposed which is used to estimate the rate of the frequency-change in the signal.Then,the system completes the signal compensation and finally completes the frequency synchronization by the fixed frequency offset estimation method.Simulation results show that the frequency estimation algorithm proposed in this thesis for dynamic frequency offset has consistent performance with the ideal carrier synchronization.The thesis also discusses the timing estimation algorithm and the phase synchronization algorithm of CPM signal.First,the timing estimation algorithm based on delayautocorrelation is given.The timing estimation accuracy of this algorithm is low.Therefore,this thesis designs the CPM signal basing on the synchronization waveform of the cyclic sequence.The DFT timing and phase estimation algorithm,and the maximum likelihood estimation algorithm for phase synchronization is given.Simulation results show that the proposed timing and phase estimation algorithm has ideal estimation performance under the unbiased conditions.Finally,this thesis improves the existing CPM synchronization frame format.By combining the synchronization estimation algorithm mentioned above,the thesis designs a multi-parameter joint estimation algorithm and conducts the fixed-point demodulation error rate analysis on this joint estimation algorithm.The results show that the bit error rate performance of the system using the joint estimation algorithm is close to the ideal synchronization.The complexity of the algorithm is low,which means the proposed algorithm is very suitable for the application in wireless communication systems.