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 NOMA-OFDM, 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.

中文翻译：

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基于索引调制的灵活非正交多址接入

非正交多址 (NOMA) 被设想为未来通信系统的有效候选者。这封信为未来的多用户通信系统提出了一种新颖的正交频分复用 (OFDM) 和基于索引调制 (IM) 的 NOMA 方案，称为 OFDM-IM NOMA。受 IM 和经典 NOMA-OFDM 的启发，用户通过调整功率分配因子和子载波激活率来利用灵活性。我们的新方案允许不同的服务用户像经典 NOMA 一样更有效地共享可用资源。结果表明，OFDM-IM NOMA 通过调整子载波激活率，在相同资源下可靠地支持高、低数据速率用户。