## 1 Introduction  
The term \"Internet of Things\" was first introduced by [PERSON] in 1996 when he deployed an application in supply chain management using radio frequency identification (RFID) tags [1]. IoT has brought a revolution in making the Internet and other real-world applications smarter. Machine to machine (M2M) communication can be used interchangeably with IoT because things can communicate with other things using the Internet without human intervention. The world has turned its attention towards IoT and its research because there are compelling applications and services. By the end of 2020, there were billions of connected smart devices [2], from which we can conclude that future technologies will be IoT dependent. Some reasons for deploying IoT include dynamic industry control, improvements in the quality of daily life, increments in resource utilization, maintaining a better relationship between humans and nature, universal transportation, global internet-working, enhanced accessibility, and amplified usability. With these extensive advantages, IoT is elevated as another industrial revolution. Smart homes, smart agriculture, smart transportation, smart health (Internet of Medical Things/IoMT), smart industry, and smart supply chains are the acclaimed applications of IoT. Each of these applications has its part in delivering an increased standard of living. Smart healthcare is an actual application of IoT and has advantages over traditional healthcare systems. These applications effectively reduce the costs and risks of medical processes, ensure timely diagnoses, improve healthcare resource utilization, support telemedical services, support self-service medicare, assists with early detection of diseases, and facilitate optimal hospital management. Besides the splendid applications and services of IoT, many challenges exist. The foremost issue in the real-time deployment of the IoT is its architecture. There is no standard IoT architecture, and organizations such as IBM, Intel, and Cisco designed their reference architectures based on their approaches to developing IoT technologies. Some of the IoT architectural standards include the ETSI IoT Standard, ITU-T IoT Reference Model, IoT-A Reference Model, Intel's IoT Architecture, Three-Layer Architecture, Middle-Based Architecture, Service-Oriented Architecture, and Five-Layer IWF Architecture. IoT Protocols play a vital role in any IoT architecture and are responsible for data exchange among intelligent devices in IoT networks. The IoT architectural standards encounter many challenges, including connectivity, data handling, heterogeneity, interoperability, privacy, scalability, and security. The billions of smart devices, including sensors, RFID tags, etc. [3], need to be connected continuously, which is tough to attain. Data handling issues exits, as vast amounts of data are generated from smart devices [4; 5]. Heterogeneity is challenging because communication must be done among devices of heterogeneous manufacturers, heterogeneous protocols, and heterogeneous architecture standards [6]. Interoperability is a significant issue because different technologies are used for communication by IoT devices [7; 8; 9]. Privacy must be ensured to build the customers' trust by protecting users' information from exposure in the IoT environment [10]. The scalability of IoT must be ensured for the adaptability of devices to changing needs of the future [11]. The security of IoT has gained researchers' attention. They have worked on security protocols and algorithms, as there are major vulnerabilities in IoT devices [12; 13]. Authentication is the major challenge under IoT security that enables access for only the authorized users [14; 15; 16; 17]. Figure 1 depicts the histogram on the number of papers published in IoT application domains in the past five years. Statistics have shown that less research is being carried out on the smart healthcare domain, even though it is the signature field in real-time. The works by [PERSON] et al.