**Abstract**

The ease deployment of Wireless sensor networks (WSNs) in the harsh and hard environment possesses a paved because the way it is. They are formed by sensor nodes which are responsible for examining environmental and corporal conditions to perform data processing. In this chapter, the manner of deployment will be presented, and how they communicate over a wireless link to unite the necessities of a specific application will be shown.

**Keywords:** WSN, system monitoring, connectivity, coverage, sensor node, routing protocol, path selection

#### **1. Introduction**

Wireless sensor networks considered as a special type of ad hoc network, where the fixed communication infrastructure and centralized administration are absent. Here, the nodes play both the role of hosts and routers [1, 2]. These Nodes can be deployed randomly or regularly in a WSN environment. There is a concession between these in terms of the number of nodes, deployment time, deployment cost, and feasibility of the placement scheme. They are smart and capable of accomplishing three complementary tasks: the reading of a physical quantity, the possible processing of this information, and the communication with other sensors [3]. Coverage guarantees the monitoring area is covered by at least one sensor node while connectivity is needed to make sure that every sensor node is precisely connected to the sink node or indirectly connected to the sink node by any other sensor nodes. In addition to their deployment fashion for an application, they form a wireless sensor network [4]. Its purpose is to monitor a geographic area, and sometimes to operate on it. Examples include a forest fire detector network, or abridging strength monitoring network after an earthquake [5, 6]. The network can include a large number of nodes (thousands). Though, their flexibility besides their ease deployment in unprotected environments, have allowed in improving people's living. Also, the capacity of the sensor on gathering information from surrounding is very helpful for a human being to make information accessible by the user [7]. In addition to their flexibility. Nowadays, they are also used in the construction of a smart home system. Moreover, Routing protocol

design factors: network efficiency and lifetime greatly depend on the quality of the protocols used. So, routing in WSN must proceed to the formation of new routes between the nodes in case the failure of communication links [8, 9]. It turns out that, efficiency in energy consumption represents a significant performance factor that limits node capacity. They are limited in memory of their major constraint but cheaper. They have limited available power because there are depleting their energy in sense as well as in communicating the signal to the base station because communication needs more power than data processing [4, 10]. Therefore, computing [4, 8, 11] resources and batteries are more limited in sensor nodes than in ad hoc nodes. Indeed, to develop this system architecture, it is necessary to start from the high-level requirements for the realization of the requested application, then to the low-level hardware requirements. In this chapter, the focus is on the communication strategy about the Design model and deployment fashion of the wireless node. It is organized as follows: Section2 gives an overview of the wireless sensor network design system, the different sensor network elements are shown in Section3, Section4 explains the deployment model of nodes, Section5 presents the vulnerabilities and challenges in WSN. We will show many areas of application of the WSN in which they are used. And finally, the conclusion is provided in Section 7.
