In this work, we address the problem of finding globally optimal power allocation strategies to maximize the users sum-rate (SR) as well as system energy efficiency (EE) in the downlink of single-cell multicarrier non-orthogonal multiple access (MC-NOMA) systems. Each NOMA cluster includes a set of users in which the well-known superposition coding (SC) combined with successive interference cancellation (SIC) technique is applied among them. By obtaining the closed-form expression of intra-cluster power allocation, we show that MC-NOMA can be equivalently transformed to a virtual orthogonal multiple access (OMA) system, where the effective channel gain of these virtual OMA users is obtained in closed-form. Then, the SR and EE maximization problems are solved by using very fast water-filling and Dinkelbach algorithms, respectively. The equivalent transformation of MC-NOMA to the virtual OMA system brings new theoretical insights, which are discussed throughout the paper. The extensions of our analysis to other scenarios, such as considering users rate fairness, admission control, long-term performance, and a number of future next-generation multiple access (NGMA) schemes enabling recent advanced technologies, e.g., reconfigurable intelligent surfaces are discussed. Extensive numerical results are provided to show the performance gaps between single-carrier NOMA (SC-NOMA), OMA-NOMA, and OMA.
翻译:在这项工作中,我们解决了找到全球最佳电力分配战略的问题,以便在单细胞多载器非横向多存取系统(MC-NOMA)的下链接中,最大限度地实现用户总和(SR)和系统能效(EE)的最大化。每个NOMA集群都包括一系列用户,在其中分别应用众所周知的叠加编码(SC)和连续取消干扰(SIC)技术;通过获得集群内电力分配的封闭式表达方式,我们表明,MC-NOMA可以等同于虚拟或超视多存取(OMA)系统,在这些系统中,这些虚拟OMA用户的有效渠道收益以封闭的形式获得。然后,SR和EEE最大化问题通过使用非常快速的装水和Dinkelbach算法来解决。将MC-NOMA等同的虚拟OMA系统转换为新的理论洞察,我们的分析可扩展到其他情景,例如考虑用户的公平率、接收控制、长期性能,以及OMA的升级后期业绩,以及未来一系列的SIMA-IMA级业绩展示结果,提供了可更新的OMA-MA系统。