Research On Modulation Recognition For Wireless Communication Signals

With the development of communication technology, modulation recognition has been widely used both in military and civilian applications, especially in the non-cooperative communication. Modulation recognition refers to obtaining the signal modulation information and some other parameters by analyzing the received signal, in the condition that there is lack of or no prior information. There are two development directions in the modulation identification area One is based on decision theory, and this method requires all parameters in addition to the modulation type, so this method has its limitation, the other is on the basis of statistical pattern recognition theory, and this method is flexible, being widely studied and applied in the direction now.In this paper, the recognition algorithms base on the high order accumulated amount are studied, and realize the modulation identification of seven digital modulation methods on the plateform of MATLAB 7.0. The signal will be recognized by re-grouping method to improve the recognition algorithm, and the recognition rate is improved. We also found that the parameters based on instantaneous information can also be applied to the high order accumulated amount recognition process.Two identification parameters of decision theory are introduced, with this joint identifying methods to improve the recognition accuracy probability.Firstly,this paper introduces the research background and the current research, describes the general process of modulation recognition;Secondly, this paper introduces the theoretical basis for modulation recognition, including the modulated signals orthogonal transformation methods, transient characteristics of information extraction and other higher order cumulants, then calculate a variety of modulation characteristic value of its cumulants. Thirdly, for the relatively low recognition accuracy of MASK signal, identification signals re-grouping algorithms is proposed in the identification process to improve the accuracy of the modulation recognition. At same time, we introduce the parameters of the high order accumulated amount which the results of recognition are relative well to the identification algorithm based on instantaneous information. The use of joint identification method to improve the recognition accuracy.In the end, we simulate the probability of modified algorithm.