Santos Yuri P, Silveira Luiz F Q
Center for Research and Innovation in Information Technology, Federal University of Rio Grande do Norte, Natal 59077-080, RN, Brazil.
Department of Computer Engineering and Automation, Federal University of Rio Grande do Norte, Natal 59077-080, RN, Brazil.
Sensors (Basel). 2023 Jun 3;23(11):5314. doi: 10.3390/s23115314.
By enabling multiple non-orthogonal transmissions, power domain non-orthogonal multiple access (PD-NOMA) potentially increases a system's spectral efficiency. This technique can become an alternative for future generations of wireless communication networks. The efficiency of this method fundamentally depends on two previous processing steps: an appropriate grouping of users (transmission candidates) as a function of the channel gains and the choice of power levels that will be used to transmit each signal. Thus far, the solutions presented in the literature to address the problems of user clustering and power allocation do not consider the dynamics of communication systems, i.e., the temporal variation in the number of users and the channel conditions. In order to consider these dynamic characteristics in the clustering of users in NOMA systems, this work proposes a new clustering technique based on a modification of the DenStream evolutionary algorithm, chosen for its evolutionary capacity, noise robustness and online processing. We evaluated the performance of the proposed clustering technique considering, for simplicity, the use of an already widely known power allocation strategy called improved fractional strategy power allocation (IFSPA). The results show that the proposed clustering technique can follow the system dynamics, clustering all users and favoring the uniformity of the transmission rate between the clusters. Compared to orthogonal multiple access (OMA) systems, the proposed model's gain was approximately 10%, obtained on a challenging communication scenario for NOMA systems since the channel model adopted does not favor a large difference in the channel gains between users.
通过启用多个非正交传输，功率域非正交多址接入（PD-NOMA）有可能提高系统的频谱效率。该技术可以成为未来几代无线通信网络的一种替代方案。这种方法的效率从根本上取决于两个先前的处理步骤：根据信道增益对用户（传输候选者）进行适当分组，以及选择用于传输每个信号的功率电平。到目前为止，文献中提出的解决用户聚类和功率分配问题的方案没有考虑通信系统的动态特性，即用户数量和信道条件的时间变化。为了在NOMA系统的用户聚类中考虑这些动态特性，这项工作提出了一种基于对DenStream进化算法进行修改的新聚类技术，选择该算法是因为其进化能力、噪声鲁棒性和在线处理能力。为了简单起见，我们考虑使用一种已经广为人知的功率分配策略，即改进的分数策略功率分配（IFSPA），来评估所提出聚类技术的性能。结果表明，所提出的聚类技术能够跟踪系统动态，对所有用户进行聚类，并有利于各聚类之间传输速率的均匀性。与正交多址接入（OMA）系统相比，在所采用的信道模型不利于用户之间信道增益存在较大差异的具有挑战性的通信场景下，所提出模型的增益约为10%。
