Novel Signal Design for Next Generation Ultra-Reliable Wireless Communications

This work presents a novel signal design based on time-domain interleaving (TDI) of orthogonal frequency division multiplexing (OFDM). Unlike conventional OFDM-TDI that introduces a one-dimensional frequency diversity, the proposed design introduces a two-dimensional frequency diversity leading to a superior symbol error rate (SER) performance for various channel conditions. The performance of the proposed signal design is evaluated using zero-forcing (ZF) and minimummean-square-error (MMSE) equalizers where the signal-to-noise ratio (SNR) and signal-to-interference-plus-noise ratio (SINR) are derived and used to evaluate the SER, outage probability (OP), and diversity order. The analytical SER results obtained, corroborated by Monte Carlo simulation, demonstrate that the proposed signal model with MMSE equalizer achieves ∼40 dB gain over OFDM and ∼7 dB over conventional TDI in Rayleigh fading channels, and it is only 2 dB from the Gaussian channel SER in Rician channels. The proposed scheme also outperforms other state-of-the-art techniques such as interleave frequency division multiplexing (IFDM) and orthogonal time frequency space (OTFS). The proposed system architecture generally follows the conventional OFDM system model, which emphasizes its compatibility and low complexity.