Covert communication based on waveform overlay with Weighted Fractional Fourier Transform signals

Most approaches for covert communication are usually done on the domain of source coding, whereas, methods on others domain are seldom seen. There are a few researches on overlay communication which is done on waveform domain, while one of the limitations is that noises have to be added in order to cover up the constellation of hidden data transmission. In this paper, we propose a new scheme for covert communication based on waveform overlay with Weighted Fractional Fourier Transform (WFRFT) signals. Signals after single parameter WFRFT present Gaussian statistics on both time and frequency domains. Moreover, the influence of multi-parameter WFRFT is similar to that of multi-path fading channels. Therefore adding noises is not necessary for this approach that capacity and security of covert communication systems based on waveform overlay techniques are increased.