Based on a comprehensive study of the modulation recognition algorithm in the non-cooperative communication, this paper reviews the current research status of the communication signal classical modulation recognition algorithm and the intelligent modulation recognition algorithm based on the deep learning. The concept and the connotation of the modulation recognition technology in the noncooperative communication are explained, focusing on the basic principle and the processing flow of the classical modulation recognition algorithm and the intelligent modulation recognition algorithm, the advantages and disadvantages of each kind of algorithms are analyzed, and the future development direction of the modulation recognition algorithm in the non-cooperative communication are discussed.

non-cooperative communication  /  modulation recognition  /  feature extraction  /  maximum likelihood  /  deep learning