In this paper, we investigate the information-theoretic secrecy performance of recent precoded faster-than-Nyquist signaling (FTN) with the aid of optimal power allocation in eigenspace. More specifically, the secrecy rate and secrecy outage probability of a fading wiretap channel, which was derived for classical Nyquist-based orthogonal signaling transmission ,is extended to those of our eigen decomposition-based FTN (E-FTN) signaling for a quasi-static frequency-flat Rayleigh fading channel. Our performance results demonstrate that the proposed E-FTN signaling scheme exhibits improvements in secrecy rate and secrecy outage probability over conventional Nyquist-based and FTN signaling transmissions. We also show that the same benefits as those of single-carrier E-FTN signaling are attainable by its non-orthogonal multicarrier counterpart, where subcarrier spacing is set lower than that of orthogonal frequency-division multiplexing.

Postprint accepted on 1 April 2021 for publication in IEEE Transactions on Wireless Communications (DOI: 10.1109/TWC.2021.3070891). (c) 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.