Wireless Sensor Network ( Wsn )

More specifically, a sensor is "a device that responds to phenomena, such as light, pressure, or heat, and generates a signal that can be measured or interpreted" [16]. The sensor network community often defines a sensor node as a wireless device which is small, capable of responding to one or several stimuli, processing the data and transmitting the information over a short distance using a radio link. Sensor nodes contain electronic circuits for minimizing power consumption [17]. Sensors are for measuring sound, light and temperature that is typically thought. However, sensors can measure other variables, such as vibrations or electromagnetic fields [18]. Sensor transmits values wirelessly to one or several BSs

Nowadays, Wireless sensor networks (WSNs) are getting more and more involved in our society, researchers and manufacture. As the use of WSNs increases the more challenges rise to make them immune and life longer. Therefore, both fields industry and academia invest money to improve the capability of the security integrity, confidentiality, and authentication. Since WSNs are distributed in unfrequented and abandoned venues, the physical security is unconcerned or less concern. The most concern is the lifetime of Wireless sensor networks, sensors have limited source of power. Thus, economizing energy will keep sensors live longer, the less power means more efficiency. Moreover, secure data is important as well, since no one attends where sensors are located, it is easy to manipulate data or steal it. Cryptography provides high security to WSNs, using algorithms to encrypt and decrypt the sent data is

The WSN infrastructures can be designed in a variety of ways to address different priorities and make the appropriate technology trade-offs based on the requirements of the certain application. There are number of interrelated design variables associated with wireless sensor networking.

A sensor node consist of a radio transceiver with internal antenna or connected to external antenna, a microcontroller and electronic circuits for interfacing with the sensors and energy source such as battery[1][7].

In our view, sensors are the “magic” of the IoT. The sensor market is enormous, with Analog Devices estimating it to approach $100 billion annually, much of which is not related to semiconductors at all. The sensor market applicable to semiconductor vendors includes micro-electromechanical systems (MEMS) - based sensors, optical sensors, ambient light sensors, gesture sensors, proximity sensors, touch sensors, fingerprint sensors and more. These chips effectively detect changes in the environment, creating the information that is ultimately transmitted via a wireless chip and interpreted through application software to create an IoT solution. Sensors or sensor networks (Smart Dust, Mesh Networks, etc.) can provide feedback about numerous

Environmental Applications: Sensor networks are already being used in ocean and wildlife monitoring; further applications could be tracking the livestock and monitoring the growth in plants, early detection of bush fires and identification of tornado motions to prevent from serious disasters.

Due to limited and non-rechargeable energy provision, the energy resource of sensor networks should be managed wisely to extend the lifetime of sensors. Sensor networks have recently emerged as a platform for several important surveillance and control applications .Each sensor has an onboard radio that can be used to send the collected data to interested parties. One of the advantages of wireless sensors networks (WSNs) is their ability to operate unattended in harsh environments in which contemporary human-in-the-loop monitoring schemes are risky, inefficient and sometimes infeasible. Therefore, sensors are expected to be deployed randomly in the area of interest by a relatively uncontrolled means, e.g. dropped by a helicopter, and to collectively form a network in an ad-hoc manner. In order to achieve high energy efficiency and increase the network scalability, sensor nodes can be organized into clusters. Data collected from sensors are sent to the cluster head first, and then forwarded to the base station. Network lifetime can be defined as the time elapsed until the first node (or the last node) in the network depletes its energy (dies).

Abstract -- The efficiency of sensor networks depends on the coverage of the target area. Although, in general, a sufficient number of sensors are used to ensure a certain degree of redundancy in coverage, a good sensor deployment method is still necessary to balance the workload of sensors in target area. In a sensor network sensors can move around to self-deploy. The deployment deals with moving sensors from an initial unbalanced state to balanced state. Therefore, several optimization problems can be defined to minimize different parameters such as total moving distance, number of moves, communication cost. There is a unique problem called communication holes in sensor networks, areas not covered by any node.

A wireless sensor network can be composed of a large number of nodes, constituting a

The wireless sensor networks have deployed in different data intensive applications including video or audio surveillance, agriculture precision, monitoring of habita. A wireless sensor network with a medium sized can get 1Gigabytes per year from habitat biologically. As the storage capacity is limited for sensor nodes, the data that is excess should get transmitted to base station for analysis and archiving. The sensor nodes should operate in power supplies with limitations like solar panels or small batteries. So that the main problem that is faced by the data-intensive wireless sensor networks is reducing consumption of energy of nodes such that the generated data will be transferred to base

Wireless sensor nodes consists of three pars first one is wireless means without wires second one is sensor mean our nodes or data sensing process third and last one is networks means connection of these nodes to form a network to communicate and report data. When we concern its quality of service it may become too wide part of research so we are promised to work only in energy efficient protocols. The reason behind wireless

Heinzelman et al. (2000) [1] Based on their findings that the conventional protocols of direct transmission, minimum-transmission-energy, multihop routing, and static clustering may not be optimal for sensor networks, proposed LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster base stations(cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability

The research efforts that addressed for the connectivity and coverage issues in WSNs are based on upon a lot of theories and assumptions. The basic concepts of connectivity and coverage are essential for understanding this issue. In this section, we describe the notions of connectivity and coverage, the category of sensor nodes, sensing models and communication models.

Wireless sensor networks (WSNs) are presented their abilities in many vital applications such as wildlife tracking, checking heart rates of human, military applications, traffic monitoring, etc, [1]. Wireless sensors have limited resources, including limited storage, limited processing facility, and communication capability. In addition, each sensor node is powered by a battery, which has a finite size and cannot be recharged or replaced due to environmental conditions [2-5]. Actually, Sensor nodes depend on their finite resources to survive. Due to these reasons, it is important to enhance the energy efficiency of nodes to improve the quality of the application service REF. The first problem of WSNs is to minimize energy consumption in

A Wireless Sensor Network (WSN) is comprised of multiple tiny devices called nodes or motes. These are distributed spatially in an environment to monitor sense and compute data wirelessly. The role of a sensor node is to evaluate different tasks. First, a node has to sense physical conditions and exchange the information with other nodes after computation. Second, it plays the important role of being a relay for different sensor nodes [1],[2],[3],[4]. These nodes can mount anywhere in the environment [2]. With recent advancements in the field of electronics these devices are becoming cheaper and smaller and are being employed in both indoor and outdoor environments. Applications include agricultural monitoring, household and military surveillance, industrial automation and robotics, and healthcare [3]. A sensor node, shown in Figure.1 is a low power device and consists of five different components namely [5], [12]