Research On Modulation Recognition Technologies Of Non-cooperation Communication

Research of modulation recognition technologies is one of the key technologies of receiver in the non-cooperation communication systems.It is of significance in both spectrum management of civilian and electronic countermeasures of militarily applications.In the existing research methods of the literature,using method of wavelet transform,mostly used in Gaussian channel conditions,but in complex communication environment,it is necessary to carry out the modulation recognition under the multi-path channel.The higher-order cumulant method is used to modulation recognition.The disadvantage is that the method needs to estimate the prior information.It is estimated that the resulting errors affect the recognition performance.In this paper,the above problems are studied in depth,the main contents are as follows:The method of combining wavelet-high-order cyclic cumulant is improved.Firstly,the 2ASK,BPSK,QPSK,16 QAM signals are transformed by wavelet transform,then the high-order cyclic cumulant transform is done.Secondly,the 2ASK,BPSK,QPSK,16 QAM signal are transformed directly by high-order cyclic cumulant transform.Finally,the ratio of the first step and the second step is used as the characteristic parameter to classify these four signals effectively under low SNR condition.This method can overcome the shortcomings of wavelet transform under Gaussian channel condition and solve the problem that the error of high order cumulant method is affected by the estimation of a priori parameters.The simulation results show that the modulation mode of the 2ASK,BPSK,QPSK and 16 QAM signals can be recognized when the signal-to-noise ratio is-5dB under multi-path fading conditions.When the number of multi-path is different,the SNR is 0dB,The recognition rate of 90% or more.