Filter Hopping Based Faster-Than-Nyquist Signaling for Physical Layer Security

The physical layer security problem with a passive eavesdropper is considered in this letter. We propose a method to obtain everlasting secrecy by exploiting inter-symbol interference (ISI) in eavesdropper. In the proposed method, the pulse shaping filter in the transmitter changes with time in the faster-than-Nyquist (FTN) signaling structure. The filter hopping pattern is pre-shared between the transmitter and the legitimate receiver. Knowing the hopping pattern, the legitimate receiver can mitigate the ISI as that in FTN. Otherwise, the eavesdropper will experience severe interference. The results show that even the eavesdropping link is much better than the legitimate link, a positive secrecy rate is also obtained. The secrecy rates for various examples of the proposed method are evaluated and the comparisons with other information-theoretic security schemes are also shown.