by different researchers for IoT, out of which the most popular architecture is three-layer architecture as shown in Figure 1.1. As per its name, this architecture has three layers, namely, i) Perception Layer, ii) Network Layer, and iii) Application Layer. This architecture basically provides the basic idea of the IoT that is further divided into five-layer architecture [2, 5, 20].
The Perception Layer is also known as a physical layer that consists of sensors and actuators. Sensors sense information from the surrounding environment and actuators actuate, i.e., perform some actions based on its sensing from the environment. So, actuators are mechanisms that control the system and accordingly act in the environment. So, basically, this layer provides/acts as input to the IoT architecture.
The Network Layer acts as an intermediate layer that provides communication between perception layer and network layer using communication devices such as routers and gateways. The basic task of this layer is to connect smart devices and its related servers. As an intermediary layer, it also transmits and processes the input data of sensing devices received from the perception layer.
The Application Layer defines various applications in which IoT is deployed. This layer performs application specific tasks and delivers service accordingly. The specific application may be smart farms, smart homes, smart cities, etc.
Figure 1.1 Three-layer IoT architecture.
Furthermore, this three-layer architecture converts into five-layer architecture. In this architecture, the perception layer and application remains and acts the same but the intermediate network layer is again divided into three sub layers such as Transport Layer, Processing Layer, and Business Layer. In this five-layer architecture, the transport layer transmits sensor data from perception layer to processing layer. Processing layer acts as a middleware layer and it can store, analyze, and process data that was received from the transport layer. To do such a task on data, this layer basically deals with many other data management technologies such as Big Data computing to process, cloud computing to store, and database management system to manage the data. The Business Layer acts on the top of the application layer and manages the entire IoT system. It consists of all application-related information such as profit model of business to that application, user privacy to the specific application, and other such business application-related information. Based on this architecture, the merits and demerits of IoT are as follows.
1.1.3 Merits and Demerits of IoT
Merits and Demerits of the IoT are as mentioned below:
Merits:
✓ Access Information: Due to association of cloud computing technology with IoT, the data access of the IoT is easy and available anywhere, anytime. So, a person involved in IoT can have easy access to such information and thereby without having his/her physical presence, it makes it convenient for that person to go about their work.
✓ Communication: IoT has important characteristics such as Interoperability. Using such characteristics, devices involved in IoT can easily talk to each other. In this way, inter-device communication will be more transparent and thereby increase efficiency of connected devices, e.g., a production unit comprises IoT technology, has Machine-to-Machine (M2M) communication that makes the product better by reducing inefficiencies, and produces faster results.
✓ Cost Effective: This merit is actually a combined benefit of the above two merits. Due to easy information access and communication, IoT devices can transmit the data very quickly over a connected component in the network of IoT. So, it saves time compared to traditional data transfer in which it occupied much more time and in that way IoT became a cost effective solution.
✓ Automation: It means to manage routine work without any human intervention. IoT helps in business automation and improves the quality product or service. IoT can collect data from the network and perform analytics on it to reveal business insights and opportunities, and thus reduce operational cost. In the automation process, IoT can also predict needs before they arise and take action accordingly to gain business profit.
Demerits:
Privacy and Security: IoT is an inter-network of things that consists of multiple devices interconnected to each other. So, such interconnection might increase the risk of any leakage of important data. In this scenario confidential information may not be safe and could be fetched/hacked by someone else easily.
increase the risk of any leakage of important data. In this scenario confidential information may not be safe and could be fetched/hacked by someone else easily.
Complexity: IoT is not only a collection of interconnected heterogeneous devices but also a combination of heterogeneous networks. So, in this environment, a single ambiguity can affect the entire system tremendously. This certainly creates a complicated state of affairs and easily increases complexity.
Lesser Jobs: Automation is one of the merits of IoT, so the need for manual processing that can be done by human beings will reduce drastically. So, the future of IoT may be one of the reasons for unemployment.
Dependability: Being complex is one of the demerits of IoT. Due to its intra heterogeneous objects and inter-heterogeneous network connectivity, it also increases dependability of such intra/interconnected object(s)/network(s). So, in case of a bug in the system, there may be a change or collapse of the entire system. Day-by-day IoT technology dominates human lifestyle and thereby increases dependability on IoT technology altogether.
1.2 Technological Evolution Toward IoT
After passing several decades of invention of an electronic device computer, in the 1960s, a communication between two computers was made possible using a computer network. Functioning of the internet commenced after the invention of TCP/IP in the 1980s. Later on, in 1991, the internet became more popular using available WWW. After the invention of www, e-mail, information sharing, and entertainment were introduced on the internet. Interconnectivity of different objects (devices) evolved over the years, and it became the base for technological evolution toward IoT. Web applications became prevalent with evolved network technology resulting in an internetworked ATM. E-commerce was also introduced during this time.
Till 2000, Information and Communication Technology (ICT) provided service related to “anytime”, “anywhere” paradigms. It means it provides service connectivity through the internet any time at any place. But in 2000, we witnessed a new era of ubiquity that suggests a new paradigm of connecting “anything” IoT [20]. Mobile internet technology was also formed parallel to evolution on IoT from 2000 to 2010. Due to the invention of mobile internet technology, social networking platforms such as Skype (2003), Facebook (2004), Twitter (2006), and WhatsApp (2009) were also introduced and thereby the users are getting connected via the internet through connecting devices [3, 4].
As shown in Figure 1.2, IoT technology was infant in 2000, and it has matured during the decade that dealt with other pioneering technologies such as RFID, WSN, and M2M communication that underwent revolution in the product automation industries and service industries. After having M2M communication, IoT which is a network of objects, that communicates with each other via different technologies such as Internet, RFID, GPRS, computers, actuators, and mobile phones without or minimal intervention of human beings. The voyage of IoT technology has been continuing in the path of IoT application domain such as Digital Locker, Smart Healthcare, Smart Vehicle, and Smart Cities. Recently, IoT technology emphasizes Smart Dust (a smaller computer than a grain of sand) collaboration with evolved nanotechnology to diagnose problems in the object system or human society.
Figure 1.2 Evolution of IoT.
Thus,