TDM based reference signal multiplexing for Faster-than-Nyquist signaling using OFDM/OQAM

This paper proposes time division multiplexing (TDM) based reference signal (RS) multiplexing for non-orthogonal multiplexing employing Faster-than-Nyquist (FTN) signaling for orthogonal frequency division multiplexing (OFDM)/offset quadrature amplitude modulation (OQAM). Accurate channel estimation is essential for FTN signaling when using a turbo soft interference canceller (SIC). We propose dividing resource elements (REs) within a physical resource block (PRB) pair into orthogonal and non-orthogonal RE multiplexing regions based on TDM to decrease inter-symbol interference and inter-subcarrier interference to a substantially low level. The RSs for channel estimation are multiplexed in the REs in the orthogonal RE region. Based on link-level simulations, we show that TDM based RS multiplexing achieves accurate channel estimation such that the loss in the required average received signal-to-noise power ratio for satisfying the average block error rate of 10^-2 compared to the case with ideal channel estimation is suppressed to within approximately 2 dB.