SNR-Optimal Spreading Sequences for Chip-Wise Faster-Than-Nyquist Signaling

This letter proposes signal-to-noise ratio (SNR)-optimal spreading sequences for faster-than-Nyquist (FTN) transmission. The peculiar association of direct sequence spread spectrum with FTN proves relevant to mitigate noticeable cyclostationary features, leading up to covert communications schemes. Considering a matched-filter-based receiver, the proposed SNR-optimal spreading sequences and their closed-form approximations outperform traditional pseudo-random noise sequences by achieving near-interference-free bit-error-probability. Our results pave the way for the design of FTN-specific multiple access techniques while ensuring a low probability of detection/intercept.