Embedding WFRFT Signals Into TDCS for Secure Communications

This paper presents a novel combinatory strategy to embed weighted-type fractional Fourier transform (WFRFT) precoding signals into transform domain communication system (TDCS). The original data can be divided into two parts. One part is modulated with the cyclic code shift keying in the traditional TDCS. The other part is first disguised as other higher order baseband modulations MPSK through WFRFT proceding process, then will further be embedded into the traditional TDCS system. A double-random scheme is designed to dynamically generate the pseudo phase for WFRFT rotation and TDCS basic function's phase. Theoretical analyses show that the higher spectral efficiency can be obtained while causing little effect on its original communication quality. The final simulations demonstrate that the constellation precoding method can help disguise the original signals into other higher order baseband PSK modulations with a controllable Gaussian-like noise. Besides, owing to the dynamically double-random phase generation scheme, the proposed combinatory WFRFT-TDCS system can gain better anti-eavesdropping capacity while maintaining its own communications' quality with regards to bit error rate performances.