Jain Preksha, Gupta Akhil, Tanwar Sudeep, Alqahtani Fayez, Raboaca Maria Simona, Said Wael
School of Electronics and Electrical Engineering, Lovely Professional University, Phagwara 144411, India.
Department of Computer Science and Engineering, Institute of Technology, Nirma University, Ahmedabad 382481, India.
Sensors (Basel). 2023 Jul 15;23(14):6425. doi: 10.3390/s23146425.
With the development of the Internet of Things (IoT), the number of devices will also increase tremendously. However, we need more wireless communication resources. It has been shown in the literature that non-orthogonal multiple access (NOMA) offers high multiplexing gains due to the simultaneous transfer of signals, and massive multiple-input-multiple-outputs (mMIMOs) offer high spectrum efficiency due to the high antenna gain and high multiplexing gains. Therefore, a downlink mMIMO NOMA cooperative system is considered in this paper. The users at the cell edge in 5G cellular system generally suffer from poor signal quality as they are far away from the BS and expend high battery power to decode the signals superimposed through NOMA. Thus, this paper uses a cooperative relay system and proposes the mMIMO NOMA double-mode model to reduce battery expenditure and increase the cell edge user's energy efficiency and sum rate. In the mMIMO NOMA double-mode model, two modes of operation are defined. Depending on the relay's battery level, these modes are chosen to utilize the system's energy efficiency. Comprehensive numerical results show the improvement in the proposed system's average sum rate and average energy efficiency compared with a conventional system. In a cooperative NOMA system, the base station (BS) transmits a signal to a relay, and the relay forwards the signal to a cluster of users. This cluster formation depends on the user positions and geographical restrictions concerning the relay equipment. Therefore, it is vital to form user clusters for efficient and simultaneous transmission. This paper also presents a novel method for efficient cluster formation.
随着物联网（IoT）的发展，设备数量也将大幅增加。然而，我们需要更多的无线通信资源。文献表明，非正交多址接入（NOMA）由于信号的同时传输而提供了高复用增益，而大规模多输入多输出（mMIMO）由于高天线增益和高复用增益而提供了高频谱效率。因此，本文考虑了一种下行链路mMIMO NOMA协作系统。5G蜂窝系统中小区边缘的用户通常由于离基站较远而信号质量较差，并且需要消耗大量电池电量来解码通过NOMA叠加的信号。因此，本文采用协作中继系统，提出了mMIMO NOMA双模式模型，以减少电池消耗，提高小区边缘用户的能量效率和和速率。在mMIMO NOMA双模式模型中，定义了两种操作模式。根据中继的电池电量选择这些模式，以利用系统的能量效率。综合数值结果表明，与传统系统相比，所提系统的平均和速率和平均能量效率有所提高。在协作NOMA系统中，基站（BS）向中继发送信号，中继将信号转发给一组用户。这种簇的形成取决于用户位置和与中继设备有关的地理限制。因此，为了实现高效且同时的传输，形成用户簇至关重要。本文还提出了一种高效簇形成的新方法。
