Graduate School of Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami City 782-8502, Japan.
School of Information, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kami City 782-8502, Japan.
Sensors (Basel). 2022 Sep 30;22(19):7445. doi: 10.3390/s22197445.
The incorporation of user-assisted cooperative relaying into beamspace massive multiple-input multiple-output (mMIMO) non-orthogonal multiple access (NOMA) system can extend the coverage area and improve the spectral and energy efficiency for millimeter wave (mmWave) communications when a dynamic cluster of mobile user terminals (MUTs) is formed within a beam. We propose threshold-based user-assisted cooperative relaying into a beamspace mMIMO NOMA system in a downlink scenario. Specifically, the intermediate MUTs between the next-generation base station (gNB) and the cell-edge MUT become relaying MUTs after the successful decoding of the signal of the cell-edge MUT only when they meet the predetermined signal-to-interference plus noise ratio (SINR) threshold. A zero forcing (ZF) precoder and iterative power allocation are used to minimize both inter- and intra-beam interferences to maximize the system sum rate. We then evaluate the performance of this system in a delay-intolerant cell-edge MUT scenario. Moreover, the outage probability of the cell-edge MUT of the proposed scheme is investigated and an analytic expression is derived. Simulation results confirm that the proposed threshold-based user-assisted cooperative relaying beamspace mMIMO NOMA system outperforms the user-assisted cooperative relaying in beamspace mMIMO NOMA, beamspace MIMO-NOMA, and beamspace MIMO orthogonal multiple access (OMA) systems in terms of spectrum efficiency, energy efficiency, and outage probability.
在毫米波（mmWave）通信中，当在波束内形成动态的移动用户终端（MUT）集群时，将用户辅助协作中继纳入波束空间大规模多输入多输出（mMIMO）非正交多址接入（NOMA）系统，可以扩展覆盖范围并提高频谱和能量效率。我们提出了一种基于阈值的用户辅助协作中继的波束空间 mMIMO NOMA 系统，用于下行链路场景。具体来说，只有当下一代基站（gNB）和小区边缘 MUT 之间的中间 MUT 成功解码小区边缘 MUT 的信号时，并且它们满足预定的信干噪比（SINR）阈值时，它们才成为中继 MUT。使用迫零（ZF）预编码器和迭代功率分配来最小化波束内和波束间干扰，以最大化系统总速率。然后，我们在对延迟敏感的小区边缘 MUT 场景下评估该系统的性能。此外，还研究了所提出方案中小区边缘 MUT 的中断概率，并推导出了一个解析表达式。仿真结果证实，所提出的基于阈值的用户辅助协作中继波束空间 mMIMO NOMA 系统在频谱效率、能量效率和中断概率方面优于波束空间 mMIMO NOMA、波束空间 MIMO-NOMA 和波束空间 MIMO 正交多址接入（OMA）系统。
