## 2 Internet of Things for Healthcare
### Elements  
Identification, sensing, and communication are the main elements of IoT, elements that will be explained briefly below. Healthcare systems need to be properly identified in order to match services with their demand. Moreover, not only the identification of the physical \"things\" but all the interaction entities also have to be clearly acknowledged in IoT solutions to ensure the correct composition and operation of the system. Nevertheless, identification has a significant extended scope and is important for all IoT applications and entities. Identification is a major topic for communication in order to address the items, services, users, data, and locations. The \"identifiers\" are applied to provide identification and can be assumed as a pattern to uniquely identify a single entity in a particular context. Electronic product codes (EPCs) [26] and ubiquitous code (uCode) [27] are identification methods that currently exist. Object identification refers to the hostname and IP address for communication on the network.  
Several addressing techniques are present in the literature, such as IPv4, IPv6, and 6 LoWPAN, that apply compression on IPv6 headers [28]. With the colossal address space offered by IPv6, all the addressing requirements of the IoT are supposed to be met. Sensing is the capture of information from the environment through a collection of data; this data can be saved in a remote, local, or cloud database. Communication is a major element of IoT, as for specific applications, such as healthcare systems, communication is crucial for patients' data sharing. Currently, there is a vast diversity of communication protocols with different battery dependability and data range transmissions, such as Wi-Fi, ZigBee, and mobile networks [29]. Most IoT devices adopt the message queuing telemetry transport (MQTT) and constrained application protocol (CoAP). These two open standards are designed to provide mechanisms for asynchronous communication. MQTT is a publish/subscribe messaging protocol designed for lightweight machine to machine (M2M) communications. CoAP is a web transfer protocol for use with constrained nodes and constrained networks designed for M2M applications [30; 31]. The IEEE 802.15.4e standard was announced by IEEE in 2012 to improve and complement the previous 802.15.4 standard [32], to address the emergent requirements of manufacturing and industrial requisites [33]. In particular, the IEEE 802.15.6, is a wireless body area network (WBAN) standard  
Figure 2: IoT visions.  
developed for enhanced health monitoring, which supports QoS data rates up to 10 Mbps, low power, and high reliability [34; 35]. Furthermore, other communication technologies are used for short-range communications, such as radio frequency identifications (RFIDs) [36], near field communication (NFC) [37], and Bluetooth low energy (BLE) [38]. A memoryless-based collision window tree plus protocol for simplified computation on anti-collision RFID was proposed by [39]. Other technologic enhancements are provided to NFC, such as a flexible and cost-effective NFC tag to allow smart devices and daily object communication in IoT environments was referred by [40]. Currently, Bluetooth 4.2 provides a suitable power efficient protocol for IoT and is applied in 6 LoWPAN networks [41]. The 6 LoWPAN has been projected to support WPAN devices with reduced battery specifications to the Internet and can be used in IoT healthcare systems to facilitate and improve energy efficiency.  
The referred IoT elements play an even more important role when applied to the healthcare domain. In fact, healthcare applications based on IoT can significantly enhance patient care, optimize resource consumption, and therefore lead to a decrease in healthcare cost. Regarding the healthcare field, privacy is of principal importance as patients' data must remain confidential. Therefore, identification, sensing, and communication elements must incorporate enhanced methods to offer high-quality medical services, while at the same time ensure privacy.