Non-orthogonal multiple access (NOMA) is being widely considered as a potential candidate to enhance the spectrum utilization in beyond fifth-generation (B5G) communications. In this paper, we derive closed-form expressions for the ergodic rate and outage probability of a multiple-antenna-assisted NOMA-based cooperative relaying system (CRS-NOMA). We present the performance analysis of the system for two different receive diversity schemes - selection combining (SC) and maximal-ratio combining (MRC), in Nakagami-m fading. We also evaluate the asymptotic behavior of the CRS-NOMA to determine the slope of the ergodic rate and diversity order. Our results show that in contrast to the existing CRS-NOMA systems, the CRS-NOMA with receive diversity outperforms its orthogonal multiple access (OMA) based counterpart even in the low-SNR regime, by achieving higher ergodic rate. Diversity analysis confirms that the CRS-NOMA achieves full diversity order using both SC and MRC schemes, and this diversity order depends on both the shape parameter m and the number of receive antennas. We also discuss the problem of optimal power allocation for the minimization of the outage probability of the system, and subsequently use this optimal value to obtain the ergodic rate. An excellent match is observed between the numerical and the analytical results, confirming the correctness of the derived analytical expressions.

中文翻译：

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Nakagami-m衰落信道中基于NOMA的接收分集协作中继

非正交多址（NOMA）被广泛认为是增强第五代（B5G）通信以外频谱利用率的潜在选择。在本文中，我们得出了基于多天线辅助的基于NOMA的协作中继系统（CRS-NOMA）的遍历率和中断概率的闭式表达式。我们在Nakagami-m衰落中针对两种不同的接收分集方案-选择合并（SC）和最大比率合并（MRC），介绍了系统的性能分析。我们还评估了CRS-NOMA的渐近行为，以确定遍历率和多样性阶数的斜率。我们的结果表明，与现有的CRS-NOMA系统相比，即使在低SNR的情况下，具有接收分集的CRS-NOMA也优于其基于正交多址（OMA）的对等方，通过达到更高的遍历率。分集分析证实，使用SC和MRC方案，CRS-NOMA都达到了完整的分集阶数，并且该分集阶数取决于形状参数m和接收天线的数量。我们还讨论了使系统中断概率最小化的最优功率分配问题，然后使用该最优值获得遍历率。在数值和分析结果之间观察到极好的匹配，从而确认了所导出的分析表达式的正确性。我们还讨论了使系统中断概率最小化的最优功率分配问题，然后使用该最优值获得遍历率。在数值和分析结果之间观察到极好的匹配，从而确认了所导出的分析表达式的正确性。我们还讨论了使系统中断概率最小化的最优功率分配问题，然后使用该最优值获得遍历率。在数值和分析结果之间观察到极好的匹配，从而确认了所导出的分析表达式的正确性。