## 1 Introduction  
The Internet of Things (IoT) and 5G have increasingly been integrated into various facets of daily life, from smart cities to smart agriculture and from traditional to smart healthcare applications [1]. IoT and 5G-based systems enable the development of more accurate diagnostic tools, more effective treatment, and devices that improve quality of life. When IoT is used in a medical setting, it is referred to as IoMT (Internet of Medical Things). IoMT has changed the medical field by enabling remote healthcare concerning social benefits and discernment by diagnosing diseases and patients monitoring with resource-efficient methods [2, 3]. By utilizing pervasive computing methods based on the IoT, it is possible to monitor and control various things of importance in the medical domain, including medical devices, physician instruction, medication, drugs, and individuals. By integrating IoT and machine learning into remote healthcare monitoring, additional efficient medical-care methods can be discovered [4, 5, 6].  
Advanced healthcare empowers telemedicine, telehealth, telesurgery and telerehabilitation, which permit remote monitoring and intensive care of subjects at hospitals/home [7, 8, 9, 10]. The modern healthcare industry requires developing a network that integrates the human body and medical devices to form a body sensor network. Furthermore, the medical data are exchanged with the help of the IoMT framework to the medical cloud [11]. Figure 1 shows the generic architecture of smart healthcare based on 5G and IoMT. There are three major components in smart healthcare based on 5G and IoT: (a) cloud data center, (b) gateways (Base-stations) and (c) body sensor networks. IoT and 5G will play an important role in providing healthcare services to distant individuals (e.g., patients, physicians, and insurance companies). The information generated by the medical devices related to the human body can be provided to relatives and medical staff to check up on the patient anywhere, at any time.  
Furthermore, in 5G and IoT-based smart healthcare, gateways are utilized as central hubs between medical devices (i.e., sensors nodes) and a cloud data center. The gateway acts as a hub to collect data and perform computation in a network for health monitoring. In addition, the gateway connects the nodes present in the network to clinic sites. These features can be successfully utilized by equipping gateways with networking, processing, and appropriate intelligence to develop smart gateways for remote healthcare monitoring.  
In 5G and IoT-based smart healthcare applications, the wearable/ambient nodes are constrained in resources, including battery, processing power, and memory. Therefore, designing a framework with energy-efficient communication for medical devices to improve the network lifetime is necessary. Clustering-based routing may be a viable technique that can perform energy-efficient communication in WSN by managing various devices in the network properly [12]. It plays a crucial part to decrease the requirements of numerous nodes, which takes part in the transmission [13]. The medical nodes are organized in groups with the help of a clustering mechanism. Each group must have at least one central coordinator node designated as the Cluster Head (CH), and the remaining nodes are designated as cluster nodes (CN). All cluster nodes in the group transmit the medical information through CH. If the cluster head (CH) selection is not optimal, addi  
Figure 1: A general architecture of smart healthcare of IoMT.  
tional communication may occur, resulting in increased energy consumption in a smart healthcare network.