High Order Modulation in Faster-Than-Nyquist Signaling Communication Systems

In this paper we investigate the highly bandwidth-efficient Faster-than-Nyquist (FTN) signaling scheme under high order modulations. The FTN system is an emerging technology which has drawn attention in the contemporary spectrum-saving communication environment. Since FTN traditionally achieves high bandwidth efficiency through increased baud-rate, binary modulation is assumed in most research of FTN. The contribution of this paper lies in the extension into high order modulations and its assessment. This enables the communication systems to achieve higher data rates for the same bandwidth and receiver complexity than binary Nyquist signaling systems. Moreover, it is shown that an additional efficiency gain can be achieved by replacing the LDPC codes from the DVB-S2 standard by new optimized quasi-cyclic (QC) LDPC codes whose parameters are matched with FTN signaling.