Asynchronous Classification of Digital Amplitude-Phase Modulated Signals in Flat-Fading Channels

This paper presents a new asynchronous modulation classifier for digital amplitude-phase modulated signals in flat-fading channels when the channel state is assumed unknown. In the design of this classifier, we propose new estimators for the unknown amplitude, time offset, and noise power that are blind to the modulation scheme of the received signal. It is shown that the proposed classifier performs well compared to the optimal classifier with perfect channel knowledge for an adequate estimation interval.