Non-orthogonal multiple access (NOMA) holds the promise to be a key enabler of 5G communication. However, the existing design of NOMA systems must be optimized to achieve maximum rate while using minimum transmit power. To do so, this paper provides a novel technique based on multi-objective optimization to efficiently allocate resources in the multi-user NOMA systems supporting downlink transmission. Specifically, our unique optimization technique jointly improves spectrum and energy efficiency while satisfying the constraints on users quality of services (QoS) requirements, transmit power budget and successive interference cancellation. We first formulate a joint problem for spectrum and energy optimization and then employ dual decomposition technique to obtain an efficient solution. For the sake of comparison, a low complexity single-objective NOMA optimization scheme is also provided as a benchmark scheme. The simulation results show that the proposed joint approach not only performs better than the traditional benchmark NOMA scheme but also significantly outperforms its counterpart orthogonal multiple access (OMA) scheme in terms of both energy and spectral efficiency.

中文翻译：

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下行链路 NOMA 网络的联合频谱和能效优化

非正交多址 (NOMA) 有望成为 5G 通信的关键推动者。然而，必须优化 NOMA 系统的现有设计，以在使用最小发射功率的同时实现最大速率。为此，本文提供了一种基于多目标优化的新技术，以在支持下行链路传输的多用户 NOMA 系统中有效地分配资源。具体而言，我们独特的优化技术在满足用户服务质量 (QoS) 要求、发射功率预算和连续干扰消除的约束的同时，共同提高了频谱和能源效率。我们首先为频谱和能量优化制定一个联合问题，然后采用对偶分解技术来获得有效的解决方案。为了比较，还提供了一个低复杂度的单目标 NOMA 优化方案作为基准方案。仿真结果表明，所提出的联合方法不仅比传统的基准 NOMA 方案表现更好，而且在能量和频谱效率方面也显着优于其对应的正交多址 (OMA) 方案。