Frequency-Packed Faster-Than-Nyquist Signaling via Symbol-Level Precoding for Multiuser MISO Redundant Transmissions

This work addresses the issue of interference generated by co-channel users in downlink multi-antenna multicarrier systems with frequency-packed faster-than-Nyquist (FTN) signaling. The resulting stems from an aggressive strategy for enhancing throughput via frequency reuse across different and squeezing signals time-frequency plane beyond Nyquist limit. spectral efficiency is proved to be increasing packing FTN acceleration factors. lower bound sampling period that guarantees information losslesness derived as a function transmitting-filter roll-off factor, frequency-packing number subcarriers. Space-time-frequency symbol-level precoders (SLPs) trade off constructive destructive interblock (IBI) at single-antenna user terminals are proposed. Redundant elements added guard interval cope vestigial IBI effects. proposals can handle channels delay spread longer than multicarrier-symbol duration. receiver architecture simple, it does not require digital demodulation. Simulations indicate proposed SLP outperforms zero-forcing precoding achieves target balance between energy efficiencies controlling amount redundancy zero (full IBI) half (destructive IBI-free) group equivalent channel.