Modulation recognition in fading channels using higher order cyclic cumulants

In this paper, we investigate the performance of a cyclic cumulant (CC) based modulation classifier for digital communication signals in flat fading channels. The proposed system assumes no a priori information regarding the signal's carrier frequency, symbol rate, or phase. For this reason, the classifier employs cyclic cumulants (CC) of different orders which are shown to be insensitive to unknown signal statistics. To capitalize on the relative strengths of different orders of CC, a hierarchical design is implemented. To further increase performance in fading channels, several multi-antenna combining schemes are investigated and compared, and are shown to provide significant performance gains over the single antenna case.