  Non-orthogonal multiple access (NOMA) is envisioned as an efficient candidate
for future communication systems. This letter proposes a novel orthogonal
frequency division multiplexing (OFDM) with index modulation (IM)-based NOMA
scheme, called OFDM-IM NOMA, for future multi-user communication systems.
Inspired by IM and classical OFDM-NOMA, users utilize flexibility by adjusting
power allocation factors and subcarrier activation ratios. Our new scheme
allows different service users to share available resources as in classical
NOMA, more efficiently. It is shown that OFDM-IM NOMA reliably supports a high
and low data rate user at the same resources by adjusting their subcarrier
activation ratios.
