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The term “Internet of Things” (IoT) implies that a large number of devices or “things” are being connected to the Internet, offering capabilities to monitor or sense physical parameters and aggregate, process and report data. Some IoT devices have constrained capabilities, meaning, e.g., that they may not be able to do any data processing or may not be able to support the IP protocol stack. Typical communication technologies used in IoT applications are Near Field Communication (NFC), RFID (tags and readers), ZigBee, Bluetooth Low Energy (BLE), Wireless LAN (Wi-Fi) and IPv6.
IoT networks allow users and smart objects to communicate seamlessly with one another irrespective of their location. IoT is also becoming an essential part of services and solutions in a wide range of application areas. Examples are smart cities (Langendörfer & Bohli, 2013), smart environment, smart water (Robles et al., 2014), smart metering (Viswanath et al., 2016), security & emergencies (Roy & Nene, 2015), retail, logistics, industrial control (O’Halloran & Kvochko, 2015), smart agriculture (Bing, 2017), smart animal tracking (Joshi, Naga VishnuKanth, Samdaria, Bagla, & Ranjan, 2008), domestic & home automation (Salman et al., 2016) and e-Health (Elhayatmy, Dey, & Ashour, 2018),(Kodali, Swamy, & Lakshmi, 2015), (Bhatt, Dey, & Ashour, 2017), (Bazzani, Conzon, Scalera, Spirito, & Trainito, 2012).
In order to benefit from the functionality of IoT devices they must be organized in a suitable manner and become part of a cluster framework. This can be achieved by forming clusters of devices sharing common characteristics and goals. Typically, one of the more powerful devices will serve as a cluster head (CH), and a number of clusters may be connected to the same gateway or server, thus forming a tree topology of gateways and clusters. Setting up the clusters and maintaining their operation will likely require a mix of human interaction (administrator function) and dynamic reconfiguration of the cluster, which could be handled autonomously by the cluster.
Figure 1. Organization of IoT Devices
Figure 1 illustrates how the IoT devices can be organized, with the gateway acting as a main communication node to the outside world. Each IoT device provides some basic functionality, e.g. sensing the current temperature, air humidity, position, etc. More complex functionality/services may require a number of devices or a cluster to collaborate.
All of these services must somehow be announced in terms of a service guide, and users who wish to perform certain tasks should be able to do a service discovery and identify relevant services. This implies that services should be filtered and matched to the user’s preferences.
Hence, the IoPTS service framework should satisfy the following requirements (Shinde & Olesen, 2016):
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A list of services must be defined, based on the parameters sensed by the IoT devices
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Users must be notified about the services in a user-friendly manner
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Services must be filtered/ranked according to the user preferences
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The service framework should be user-centric, energy efficient and scalable.