Subcarrier Index Modulation Super-Nyquist Carrierless Amplitude Phase Modulation for Visible Light Communication Systems

In the past decade, novel index modulation (IM) has emerged as a promising technology widely employed in wireless communications. In this paper, the subcarrier index modulation super-Nyquist carrierless amplitude phase (SIM-SCAP) modulation scheme is proposed and investigated to enhance the system spectral efficiency (SE) and the energy efficiency of the multiband CAP (
m
-CAP) scheme in bandlimited visible light communication (VLC) systems. By innovatively combining the index modulation technique with the non-orthogonal
m
-CAP technique, the SIM-SCAP scheme can sustain higher system SE than the
m
-CAP scheme along with a reduced system complexity for transceivers. Furthermore, the ICI mitigation schemes are employed further to enhance the throughput performance of the SIM-SCAP scheme. It is shown that the SIM-SCAP scheme with ICI mitigation DSP achieves ∼30% SE enhancement compared to the non-orthogonal
m
-CAP scheme. Furthermore, under maximum bandwidth and minimum transmission rate requirements, the SIM-SCAP scheme yields a Q factor gain of 5.5 dB. The results validate the unveiling advantage of the SIM-SCAP scheme in offering high SE transmissions, which is a promising candidate in designing bandlimited multi-user access optical communication systems.