# Recent Advancement of Data-Driven Models in Wireless Sensor Networks: A Survey
## 2 WSNs Architecture Overview  
A typical WSN's architecture consists of a sensing field that contains various kinds of sensor nodes such as data-sensing nodes, the base station, and the sink, all of which are related to each other. In the sensing field, the base station collects the data from all of its sensor nodes and transfers these data to the sink node. The sink node collects the data from all the sensor nodes efficiently due to its high processing, functionality, and memory [10]. Each sensor node is composed of different basic components, namely a sensing unit, microcontroller, wireless transceiver, and battery by determining the physical objects. After the acquisition of the sensing unit, the data are digitalized by using a microcontroller, processing power, and coordination capability [11]. Now, the data are transferred into the other connected sensor nodes through the transceiver. The transceivers are used for the transmission and reception of the data. WSNs are divided into four types based on the kind of sensor node: static, mobile, hybrid, and mobile robot [12]. Normally, all deployment of static wireless sensor networks (S-WSN) sensors is static, but mobile wireless sensor networks (M-WSN) sensors, such as i-Mouse, are fitted with locomotive platforms and may move after the first installation. Another side, a hybrid wireless sensor network (H-WSN) integrates both static and mobile sensors. Instead of implementing mobile sensors, robots are utilized to handle static sensors; these networks are known as WSRNs. Robots within wireless sensor and robot networks (WSRNs), also known as carrier-based, contain the static sensors as payload and install these sensors in suitable areas. Therefore, in this scenario, several of the predetermined deployment models are adopted while the robot's mobility is optimized using a route optimization algorithm [13]. Finally, battery power is the main component that is used in all steps of data communication through the data process, and users can easily access data and information according to need through the internet [14]. The typical network architecture of sensor nodes in WSNs is shown in Figure 1.  
The data transmission is transferred from one location to another location through the routing protocol in WSNs. A well-designed WSN protocol helps the network live longer. For this reason, the proposed protocol is made with considerably more emphasis than the other aspects of design. The WSN protocol architecture is designed to be energy efficient and meet application needs. There are two types of data collection protocols now in use: hierarchical protocols and non-hierarchical protocols [15]. The attraction of a non-hierarchical collection of protocol modules over a completely vertically stacked design, which is common in several other groups of communication systems, is that events transmitted through one layer (module) do not need to be analyzed with an intermediary layer. Nodes are drawn to the sink node because it avoids constraints and is maintained within the transmission range. Non-hierarchical WSN deployments are usually best for an event-driven data model, but hierarchical architecture implementations are better for long-term deployments. The hierarchical routing architecture gives higher coverage, while the geographic routing implementation delivers an extended network life. It may seem prudent to adopt a hybrid method, where the most computationally intensive tasks are done by a power mode [16]. Chain, tree, grid, and cluster-based hierarchical routing are the four primary kinds of hierarchical routing. Chain-based routing is simple to install and manage; the chain's structure does not vary frequently, and nodes always transmit data to the closest node. As a result, the amount of energy required to build a chain is minimal. The drawback in chain-based routing is that there may be various nodes inside a chain; however, if the sensor node is far from the sink node, the data must travel a long distance to reach the sink node.