# A Lightweight Secure and Energy-Efficient Fog-Based Routing Protocol for Constraint Sensors Network
## 2 Related Work  
The IoT-based systems are comprised of physical objects with a huge number of sensor nodes that are deployed in either static or mobile scenarios with high powerful BS. All the devices are connected through wireless links to capture the monitoring area in terms of various attributes like weather, humanity, temperature, vehicle movements, etc. The observing data is collected by sensor nodes and using the selected cluster heads it is transmitted to BS. The cluster heads or gateway nodes are further connected to BS using the Internet, and different application users obtained their needed information. However, several efficient routing protocols for constraint sensors network have been proposed [17; 18; 19; 20], and improved the network performance compared to traditional solutions. Nonetheless, the still research community is currently trying to increase the nodes' performance for such an IoT-based system in terms of stability, delivery ratio, and least delay rate due to their limited constraints. Although cloud-based paradigms have been used with the integration of IoT-based sensors and have overcome the issue of scalability and reducing computation load for sensor nodes, the problem of network latency still exists at the end of application users. Moreover, the prohibited entries of opponent nodes lead to several security threats and most of the resources like memory, processing chips, etc.,may be inaccessible to network nodes and lead to untrustworthiness in data transmissions. Therefore, to efficiently undertake the network-wide routing, securely transfer data, and make a strong authentication, the research community is still focused on an intelligent and fault-tolerant routing solution [21; 22; 23]. In [24], the authors proposed a novel network architecture named cluster-based self-organization data aggregation that aims to organize the nodes in self-organized clusters for data aggregation and forwarding. The proposed solution improved the network lifetime and decreases the network overheads; however, the clusters of network nodes are not formulated in a uniform manner. Also, the construction of routing paths is not reliable and stable in terms of data security and robustness. Moreover, the concern for network threats is not considered in the proposed solution. In [25], the authors proposed a novel, light-weight, efficient key exchange, and authentication protocol suite called the Secure Mobile Sensor Network (SMSN) Authentication Protocol to ensure data confidentiality and validity. In the proposed solution, the mobile sensor node initiates an authentication process and obtained a re-authentication ticket from BS. Later, the mobile node exploits this obtained re-authentication ticket while exchanging multiple data to various sessions or when moving across the network. However, the proposed SMSN solution does not consider the link measurement for the performance of fault-tolerant and trustworthy routing and, as a result, the solutions lead to frequent re-routing and re-transmissions of data packets. Also, it consumed additional energy and increased network overheads to determine the up-to-date position of mobile sensors. The authors in [26] analyzed the problem data gathering from wireless sensor networks to a cloud with multiple mobile sinks, and formulated a constrained optimization problem, which proved to be NP-hard. In this solution, the authors proposed a time adaptive schedule algorithm (TASA) and used multiple mobile sinks to gather the network data. Moreover, the solution reduces the transmission cost by forming the minimum spanning tree (MST). Simulation-based experiments were performed, and it was revealed that the algorithm improves the energy consumption with the least data latency during the data transmission among WSN and cloud. However, the proposed algorithm is not able to cope with optimize routing decisions and, in addition, data security can be compromised in the existence of potential threats.