Security is the key issue in many communication applications especially for military applications. In contrast to this, the authorities of boarder security may wish to monitor unlicensed transmitters for jamming their signals. The necessary action of doing so is to identify or recognize the modulation class of that intercepted signal. Such type of actions also arises in several other applications such as interference management, signal authorization, verification, and selection of appropriate demodulation techniques in electronic combat, threat analysis, and so on. Modulation recognition is also useful to recognize the suspicious transmitter in the near geographical site and to generate jamming signals to stop communication between the suspicious users. In recent civilian applications, a greater number of modulation formats can be employed by a transmitter to manage the data rate, to reduce the individual band-widths of every user, and to assure the integrity of the message. However, the group of modulation formats is known both to transmitter and receiver. The choice of the modulation format is adaptive and may not be known at the receiving end. Therefore, an AMC mechanism is required for the receiving end to recognize modulation format of the received signal and to select the proper demodulation approach in order to recover the original message. Moreover, in civilian applications, several techniques developed to reduce overhead of reference signals required for channel estimation have motivated the research in blind and semi-blind MIMO techniques. Blind techniques are also expected to play a role in software defined radio and cognitive radio. Configuration information required by a software defined radio system is transmitted as overhead to the data. Intelligent receivers capable of extracting this information blindly may improve transmission efficiency through reductions in overhead, i.e., automatic modulation classification eliminates the need for supplementary information on the modulation type .
展开▼
