Wireless Sensor Networks: Applications

*Bhargavi Dalal and Sampada Kukarni*

### **Abstract**

Wireless sensor networks consist of small nodes with identifying component by sensing, computation, and wireless communications infrastructure capabilities. Many path searching means routing, power management, and data dissemination protocols have been specifically designed for WSNs where energy awareness is an essential design issue. Routing protocols in WSNs might differ depending on the application and network architecture. Wireless Sensor Networks (WSNs) provide several types of applications providing comfortable and smart-economic life. A multidisciplinary research area such as wireless sensor networks, where close collaboration in some users, application domain experts, hardware designers, and software developers is needed to implement efficient systems. The easy molding, fault tolerance, high sensing fidelity, low price, and rapid deployment features of sensor networks create various new and thrilling application areas for remote sensing. In the future, this wide range of application areas will make sensor networks an essential part of our lives. However, understanding of sensor networks needs to satisfy the constraints presented by factors such as fault tolerance, scalability, cost, hardware, dynamic topology, environment, and power consumption.

**Keywords:** Applications of Wireless Sensor Network

## **1. Introduction of wireless sensor network**

Wireless sensor network (WSN) refers to a collection of sensors for observing, monitoring and recording the physical conditions of the environment [1]. After observing and recording the behavior of sensors, consolidating the collected data at a central location is the main task. WSNs measure environmental conditions like wind, humidity, temperature, pollution levels of sound, air and so on [2].

WSNs consist of spatially distributed and independent sensors to observe and monitor physical and environmental conditions. They are helpful to collectively pass recorded data through the network to a central location. Some of the networks are bi-directional, i.e. both collecting data from distributed sensors and supporting control of sensor activity.

Spatially dispersed and dedicated networks help to collect different parameters with special sensors which are included in the WSN. The development of WSN was motivated by mainly military applications such as battlefield surveillance. Nowadays, such networks are used in many applications like industry, consumer applications. Few of the applications such as industrial process monitoring and control, machine health monitoring, and so on.

#### **2. WSN components**

The main component of WSN is node. A sensor network generally consists of tens to hundreds or thousands of relatively small nodes, each equipped with one or more sensing devices [3]. Here each node is linked to one or numerous sensors. Each such node normally has several parts: a radio transceiver with an inner antenna or connection to an exterior antenna, a microcontroller, an electric circuit for interfacing with the sensors and an energy source, usually a battery or an implanted form of energy collecting. A node with a sensor implanted may vary in size. Size of a node can be from that of a brick to the size of a grain of dust. The cost of sensor nodes is also variable. They may range from a few to hundreds of dollars, depending on the complexity of the individual sensor nodes. The potential of different properties such as energy and its consumption, memory, computational speed and communications bandwidth varies the size and cost of sensor nodes. Hence, size and cost limitations on sensor nodes result in corresponding constraints on resources. The use of specific sensor nodes with required quality of various properties depends on the application.

b. Processing Unit

*Wireless Sensor Networks: Applications DOI: http://dx.doi.org/10.5772/intechopen.97079*

d. Power Supply

a. Base Station

2. Sensor Network

b. Routers

3.Network Architecture

a. Single Hop

b. Multi Hop

own data and network analysis.

transmit and receive the signals.

**5**

Following figure depicts the same.

battery like CR-2032, is used to power the entire system.

**2.1 Sensor node**

i. Microcontroller

ii. Microprocessor

ii. Radio Transceiver

A sensor node is a combination of different subunits and all they help to perform the functionality of the sensor node. Different units help to sense, record, monitor

Even though the name, a Sensor Node comprises not only the sensing component but also other important characteristics like processing of recorded data, communication with servers and storage units to store recorded data. With all these characteristics, components and enrichments, a Sensor Node takes responsibility for data collection, data correlation, and fusion of data from other sensors with its

The above **Figure 2** shows the sensor node is a combination of different units. They are, sensing unit, processing unit, communication unit and power unit. All of them have their own responsibility to sense data, process data and communicate sensed and processed data to servers respectively. This can be done with the help of a power unit as all the components are low-power devices. And hence a small

The sensing unit comprises sensor and Analog to Digital Converter (ADC). Sensor collects the Analog data from the physical world and an ADC takes the responsibility of conversion of this Analog data to Digital form. The second unit is the processing unit, which is usually a microprocessor and/or a microcontroller. They perform intelligent data processing and manipulation. The next unit is a communication unit consisting of a radio system and an antenna. Here, radio transceivers are used for data transmission and reception and antenna helps to

and analyze the data which is collected from physical conditions [4].

c. Communication System

i. Antenna

The base stations are another important component of WSN. They are one or more components of the WSN with many more qualities like computation, energy conservation and communication to share recorded data. They play a role of gateway between sensor nodes and the end user. These gateways are usually useful to forward recorded data from the WSN on to a central location. Central locations are nothing but the servers. Other special components in WSN are routers. Routers specially designed to compute, calculate and distribute the routing tables.

As of now, we have seen very few but important components of WSN. Following **Figure 1** explains the various components of WSN.

1.Sensor Node

a. Sensing Unit

i. Sensor

ii. ADC

**Figure 1.** *Various components of sensor node.*

*Wireless Sensor Networks: Applications DOI: http://dx.doi.org/10.5772/intechopen.97079*

b. Processing Unit

i. Microcontroller

ii. Microprocessor

c. Communication System

i. Antenna

ii. Radio Transceiver

d. Power Supply

2. Sensor Network

a. Base Station

b. Routers

3.Network Architecture

a. Single Hop

b. Multi Hop

#### **2.1 Sensor node**

A sensor node is a combination of different subunits and all they help to perform the functionality of the sensor node. Different units help to sense, record, monitor and analyze the data which is collected from physical conditions [4].

Even though the name, a Sensor Node comprises not only the sensing component but also other important characteristics like processing of recorded data, communication with servers and storage units to store recorded data. With all these characteristics, components and enrichments, a Sensor Node takes responsibility for data collection, data correlation, and fusion of data from other sensors with its own data and network analysis.

Following figure depicts the same.

The above **Figure 2** shows the sensor node is a combination of different units. They are, sensing unit, processing unit, communication unit and power unit. All of them have their own responsibility to sense data, process data and communicate sensed and processed data to servers respectively. This can be done with the help of a power unit as all the components are low-power devices. And hence a small battery like CR-2032, is used to power the entire system.

The sensing unit comprises sensor and Analog to Digital Converter (ADC). Sensor collects the Analog data from the physical world and an ADC takes the responsibility of conversion of this Analog data to Digital form. The second unit is the processing unit, which is usually a microprocessor and/or a microcontroller. They perform intelligent data processing and manipulation. The next unit is a communication unit consisting of a radio system and an antenna. Here, radio transceivers are used for data transmission and reception and antenna helps to transmit and receive the signals.

**Figure 2.** *Sensor node in WSN.*

#### **2.2 Sensor network**

Till now we have seen that the sensor node collects information from the physical environment and transmits it to the sensor network. Now it's time to learn the sensor network. Sensor network consists of two components. They are namely base station and a router.

Here the network architecture has two main aspects. First one is a single-hop

**Figure 4** explains the concept of single-hop network architecture. In a Singlehop network architecture, each sensor node is connected to the base station. It allows long distance transmission as well. As it allows long distance transmission, obviously the energy consumption for communication will be significantly higher.

As we have seen the power consumption is significantly high in single-hop network architecture, this drawback is overcome in multi-hop network architecture. Hence, Multi-hop network architecture is usually used for better power consumption. **Figure 5** depicts the concept of multi-hop network architecture.

Due to intermediate nodes in multi-hop network architecture, the load of one single link between the sensor node and the base station reduces. Here the data is transmitted through one or more intermediate nodes. Hence, it is more efficient

Multi-hop network architecture can be implemented in twofold. Flat network architecture and Hierarchical network architecture. In flat architecture, the base station broadcast commands to all the sensor nodes but the sensor node with identical query will respond using its peer nodes via a multi-hop path.

In hierarchical architecture, a group of sensor nodes are formed as a cluster and the sensor nodes transmit data to consistent cluster heads. The cluster heads can

network architecture and the other one is multi-hop network architecture.

And hence it affects the tasks of data collection and computation.

than that of single-hop network architecture.

**Figure 3.**

**Figure 4.**

**7**

*Single hop network architecture.*

*Network architecture.*

*Wireless Sensor Networks: Applications DOI: http://dx.doi.org/10.5772/intechopen.97079*

then communicate the data to the base station.

Base stations are often thought of as just a central component that is used to gather data from distributed nodes [5]. Here base station acts as a gateway between other networks through the internet. Once the base station receives the data from the sensor nodes, a base station performs some processing on collected data and sends the processed information to the user using the internet.

As we have seen previously, the main task of a sensor node is to sense data and send it to the base station. For the same, a routing path is essential. And this responsibility is handled by a second component of the sensor network. It is a router. For finding the efficient routing path from the source node to the base station there are a lot of proposed routing protocols. The design of routing protocols for WSNs must consider the power and resource limitations of the network nodes, the time-varying quality of the wireless channel, and the possibility for packet loss and delay.

#### **2.3 Network architecture**

To observe the behavior of sensors in sensor nodes, and then to communicate with the base station, they must connect through networking. Here is the role of the second component of WSN. It is network architecture. To observe a physical environment co-operatively, a huge number of sensor nodes are arranged in a massive area. That's why the networking of these sensor nodes is equally important. There is communication not only between sensor nodes in a WSN but also with a Base Station (BS) [6]. Here for this communication, WSN uses wireless communication. Hence, this network is named as wireless sensor network (**Figure 3**).

As mentioned above, here in network architecture, there is not only the communication between intermediate sensor nodes or between sensor nodes and base station, the base station also communicates with sensor nodes. The base station sends directions to the sensor nodes. The sensor node performs the task accordingly by working in co-operation with other sensor nodes in the network.

**Figure 3.** *Network architecture.*

Here the network architecture has two main aspects. First one is a single-hop network architecture and the other one is multi-hop network architecture.

**Figure 4** explains the concept of single-hop network architecture. In a Singlehop network architecture, each sensor node is connected to the base station. It allows long distance transmission as well. As it allows long distance transmission, obviously the energy consumption for communication will be significantly higher. And hence it affects the tasks of data collection and computation.

As we have seen the power consumption is significantly high in single-hop network architecture, this drawback is overcome in multi-hop network architecture. Hence, Multi-hop network architecture is usually used for better power consumption. **Figure 5** depicts the concept of multi-hop network architecture.

Due to intermediate nodes in multi-hop network architecture, the load of one single link between the sensor node and the base station reduces. Here the data is transmitted through one or more intermediate nodes. Hence, it is more efficient than that of single-hop network architecture.

Multi-hop network architecture can be implemented in twofold. Flat network architecture and Hierarchical network architecture. In flat architecture, the base station broadcast commands to all the sensor nodes but the sensor node with identical query will respond using its peer nodes via a multi-hop path.

In hierarchical architecture, a group of sensor nodes are formed as a cluster and the sensor nodes transmit data to consistent cluster heads. The cluster heads can then communicate the data to the base station.

**Figure 4.** *Single hop network architecture.*

would be connected to the continuous power supply, so that wireless parts can use low power to transfer data to them and also nodes can go in the standby mode from

The characteristics of some applications include low cost, small size, low power consumption, robustness, flexibility, resiliency on errors and faults, autonomous

An active care approach that is dynamic works as an 'on-the-fly'-based initiating technique that creates a fresh topology when the existing one is no longer ideal. The main advantage of its capability is to create an active prior version, that the system becomes more energy-efficient. These networks are characterized by a need for low power consumption and low levels of physical security and broadcast physical medium. Asymmetric techniques like RSA are not to be used as are inefficient and

MANET means Mobile ad-hoc Network. It is also named as wireless ad hoc network or temporary wireless network. It usually has a searching path interacting environment on top of a Link Layer ad-hoc network. They consist of set of mobile nodes connected wirelessly in a self-configured, self-healing network without having a fixed infrastructure [7]. These wireless sensor nodes are allowed to move freely on a random basis as the network topology changes frequently. Each node acts as a router as they accelerate traffic to other specified nodes in the network. **Figure 7** shows the structure of an ad-hoc network which consists of a peer-topeer, self-forming, self-healing network. Typically communicate at radio frequen-

Reconfiguration can be made in such a way that the new network has the same topology (only some nodes have exchanged their places) or allowing any arbitrary

**Figure 8** shows clustered-based wireless sensor networks have been extensively

topology, also, it is not necessary to modify the routing algorithm.

used in the literature in order to achieve considerable energy consumption

time to time (**Figure 6**).

*Wireless Sensor Networks: Applications DOI: http://dx.doi.org/10.5772/intechopen.97079*

**3.2 Dynamic characteristics**

consume too much power.

cies (30 MHz-5GHz).

**Figure 6.**

**9**

*Structure of static network.*

*3.2.1 Ad-hoc network like MANET*

mode of operation, and often privacy and security.

**Figure 5.** *Multi hop network architecture.*
