This chapter includes the introduction to the Wireless Sensor Network (WSN) . It describes the basics concepts, characteristics, applications and various security attacks related to Wireless sensor networks.
1.1 Wireless Sensor Networks (WSN)
A wireless sensor network is made up of minor sensor hubs or nodes which are deployed in different environments. These sensors are smart dispensable micro sensors and can be deployed on the ground, vehicles, in air and water.
Each node has inserted operational capacity, and have various locally available sensors that helps in the deployment of full network. The activity of the deployed nodes is to gather the information from each other and send the information to the base station. These sensor nodes are sent in unattended condition .A wireless sensor network comprises of a wide range of segments of which a sensor node is a little yet crucial part. The attributes of a decent remote sensor arrange incorporate power productivity, adaptability, responsiveness, unwavering quality and portability1.
Figure 1.1 Wireless Sensor Networks3
1.1.1 Basic components of sensor node
Microcontroller, transceiver, external memory and power source are the basic components of sensor node. The sensor node structure comprising of its various components as follows:
WSN Sensor Node
Figure 1.2 Sensor Node Structure
Controller: Microcontroller is used in sensor node because of its low cost, less power consumption. They usually process data, perform task and control the functionality of other neighbour nodes.
Transceiver:Transceiver has functionality of both transmitter and receiver. The operational state of transmitter is receiving, transmit, idle and sleep. The transmitter of new generation has built in state machine that can performs few operations automatically
External memory: The two types of memory based on the purpose of storage are: user memory i.e. for store application or personal data of users and another one is program memory i.e. used for programming the device
Power source: We should ensure that there is always enough energy available to power the system. Sensor nodes require power for communication and data processing.
1.2 Characteristics of Wireless Sensor Networks
· Scalability The capacity for a system to develop as far as the quantity of nodes joined to the remote sensor coordinate with causing exorbitant overhead can be named as its scalability. At first this type of a network is made up of handful of nodes but it is important that they can join more nodes as per demand. But with the increase in network size will result in higher chance of breakage between communication link.
· Responsiveness The network is considered as responsive if it can adapt itself with the change in topology. But there are also various limitations of highly responsive network like the scalability will decrease if the network is highly responsive.
· Reliability It is a basic requirement for any network. The network you established should be reliable in data transmission. It is important that your data transmission should remain constant with the change of the topology or structure. But if we increase the number of nodes over the network than it gets very difficult to maintain the reliability.
· Mobility The mobility of the network is its capacity to nodes that are mobile and their changeable data routes. It is important for wireless sensor network to be highly responsive in order to manage its mobility. Thus, it gets difficult to design a network that is large in scale and highly mobile.
· Power Efficiency It’s is harder to make a network that is highly reliable and responsive so it can deal with mobility because it gets the efficiency levels of device in question. It is ability of node to perform its computation on less power levels and use less power for its working. It is very important factor because of the idea that the nodes are deployed in environment with no proper access of power point.
· Ability to withstand brutal environmental conditions : A wireless sensor network (WSN) are unattended self-ruling sensors to observe physical or natural conditions, for example, temperature, sound and weight. Hence the sensor nodes are have be adequate capacity to go through harsh ecological conditions.
1.3 Applications of Wireless Sensor Networks
Area Research on sensor networks was initially inspired by military applications. Cases of military sensor networks run from expansive scale acoustic surveillance frameworks for sea observation to little networks of unattended ground sensors for ground target identification. Nonetheless, the accessibility of these sensors and communication networks has brought about the improvement of numerous other potential applications, from foundation security to modern detecting. There are few examples2: