# Efficient and Secured Mechanisms for Data Link in IoT WSNs: A Literature Review
## 3 WSN in IOT  
Heterogeneous WSNs that connect a diverse set of intelligent sensors have formed the foundation for IOT-based systems all around us, promising significant advancements shortly. With the rapid expansion of these technologies, there has been an increase in the temptation to reduce their energy use. Tremendous advances in communication and information flow have contributed to unsustainable increases in energy consumption and carbon emissions. However, sensor nodes must operate successfully for extended periods (even years) in most applications because of various application criteria (e.g., environmental management, agriculture, border surveillance or protection, etc.). Dead nodes may affect data reliability, precision, and device compatibility, which are essential for an application's long-term sustainability. A sensor node is typically composed of four primary units: the processing unit, the sensing/identification unit, the communication unit, and the power supply unit, as shown in Figure 5. Filters, amplifiers, transducers, comparators, and other secondary components are combined with the core above. Data from the workplace are collected and detected by the sensor device. All the other devices require power, which is supplied by the power unit (usually a battery-limited one) and  
Figure 4: Clustered network architecture (Adapted from ref. [13]). delivered to the BS (base stations) through the communication unit, which performs data processing functions, including data collection, as well as data manipulation duties, such as data gathering. The quantity of energy that a sensor node utilizes is based on its present state, which may be one of three states: sleeping, idle, or active. In active mode, the node uses the most significant energy. Due to the transmission and reception of information, the sensing device can release as much energy as is feasible while absorbing as little as possible. Though the energy the processing unit uses is far less than that required by the radio subsystem, it is more significant than that required by the sensor subsystem. There is a relationship between factors such as communication distance, monitoring cases, operational criteria, and the activities taken by each unit. When the node is idle, it waits for data packets to arrive from another node. Data transfer may waste 50% to 100% more energy if more power is required to run the CPU, radio, and other components. When the node is resting, substantially less energy is lost since no processing is undertaken and the communication unit is switched off. However, other energy dissipation problems exist, such as packet losses, packet collisions, physical channel challenges, frame overhearing, overhead protocols, and overhead processing. As a result, IoT researchers have been driven to develop energy-efficient and renewable IoT solutions [22]. Figure 5 shows the typical IoT architecture for WSN. Smart technology is becoming an increasingly important part of human life. WSNs are becoming more critical to the Internet of things every day. Consequently, the obstacles intensify, and the demand for reform becomes even more imperative. WSNs and the Internet of things may benefit from machine learning. A new operational framework for next-generation wireless sensor networks based on the IoT has been proposed. Using a three-layer transmission method, the nodes can communicate efficiently concerning energy. However, there is a need to develop an IoT-based WSN architecture that is flexible, automated, and provides encryption in a lightweight manner. The proposed architecture also provides a reliable connection among the WSN's nodes based on privileges to maintain and exchange information. Similarly, for mobility, the proposed architecture uses dynamic clustering techniques. The cluster heads (CH) are rotated regularly in an iterated manner using a local dynamic cluster selection process with the primary goal of increasing the QoS and balancing their power consumption.