On Performance of Cooperative OFDM Index Modulation Aided Hybrid NOMA System

Spectral efficiency (SE) is critical for enhancing cellular applications in next-generation communication systems. Non-orthogonal multiple access (NOMA) supports the need for energy and SE to serve several users concurrently while sharing the frequency and time resources. Additionally, integrating index modulation (IM) with the orthogonal frequency division multiplexing (OFDM) system provides a new level of information transmission by allowing the selection of subcarrier indices and the resulting selection diversity gain to improve the SE. Moreover, compared to a prior cooperative two-user NOMA system, cooperative IM over a hybrid NOMA that includes both the code and power domain benefits more users. This paper describes a cooperative relaying OFDM-IM aided hybrid downlink NOMA system serving three users simultaneously. The error rate performance is assessed using the maximum likelihood detector. Furthermore, the results are simulated using various modulation pairs and power levels.