Modulation recognition method of time-frequency aliasing signals in single-channel
Pengbo Li, Lin Qi, Junliang Wang · 2020
In the field of modern wireless communication, electromagnetic spectrum resources are increasingly tight, and it is becoming more and more common for one single antenna to receive multiple communication signals. High-order cumulant can suppress noise well, it has been widely used for modulation recognition of single signal in single-channel but seldom used for time-frequency aliasing signals in single-channel. This is because we need to use estimated carrier frequency for down-conversion to obtain the baseband signal before calculating high-order cumulant. But there will be more than one carrier frequencies when they are time-frequency aliasing signals. So it focuses to select the suitable carrier frequency to improve the calculation accuracy of high-order cumulant and recognition performance. In this paper, an algorithm of selecting suitable carrier frequency which uses the nature of high-order cumulant is proposed. And also two high-order features have been analyzed and constructed. Then they are used to classify seven kinds of timefrequency aliasing signals randomly combined by the digital modulated signals including BPSK, QPSK, 8PSK and 4ASK. The simulation results show that the algorithm has better recognition performance.