In the next generations of communication systems, resources’ scarcity devolves to a more critical point as a consequence of the expected massive number of users to be served. Furthermore, the users’ contradicting requirements on quality of service forces the network to behave in a dynamic way in terms of the multiple access orchestration and resource assignment between users. Hence, the linear relation between the number of served users and the required (orthogonal or semi-orthogonal) resources in the orthogonal multiple access (OMA) schemes is no longer sufficient. As promising candidates, Non-orthogonal multiple access (NOMA) schemes and index modulation (IM) techniques are emerging to satisfy the ever-increasing connectivity demands and spectral efficiency. In this article, a novel IM-based NOMA downlink scheme, termed as IM-NOMA, is proposed, where the base station (BS) selects a channel or more to serve each user based on the IM concept and the corresponding power level is allocated based on the NOMA concept. At the users’ ends, maximum likelihood and successive interference cancellation (SIC) detection methods are considered and their error rate, outage probability and computational complexity are studied. Simulation results confirm the advantage of the proposed IM-NOMA scheme and that it can outperform the conventional NOMA system.

中文翻译：

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一种新颖的下行IM-NOMA方案

在下一代通信系统中，由于预期将服务大量用户，资源的稀缺性恶化到了一个更关键的点。此外，用户对服务质量的相互矛盾的要求迫使网络在用户之间的多路访问编排和资源分配方面以动态方式运行。因此，在正交多址访问（OMA）方案中，服务的用户数量与所需的资源（正交或半正交）之间的线性关系不再足够。作为有前途的候选者，非正交多址（NOMA）方案和索引调制（IM）技术正在出现，以满足日益增长的连接性需求和频谱效率。在本文中，提出了一种新颖的基于IM的NOMA下行链路方案，称为IM-NOMA，其中基站（BS）根据IM概念选择一个或多个信道为每个用户服务，并根据NOMA概念分配相应的功率水平。在用户端，考虑了最大似然和连续干扰消除（SIC）检测方法，并研究了它们的错误率，中断概率和计算复杂性。仿真结果证实了所提出的IM-NOMA方案的优势，并且其性能优于传统的NOMA系统。研究了中断概率和计算复杂度。仿真结果证实了所提出的IM-NOMA方案的优势，并且其性能优于传统的NOMA系统。研究了中断概率和计算复杂度。仿真结果证实了所提出的IM-NOMA方案的优势，并且其性能优于传统的NOMA系统。