**3. Characteristics of WSN**

The important characteristics of a WSN include


These are few major and common characteristics of WSN. But, the characteristics of wireless sensor networks for various applications may be quite different. They also can share common characteristics too.

Sensor nodes have been defined into two characteristics.

1.Static characteristics

2.Dynamic Characteristics

Although here as we mentioned above some characteristics, but now we are focusing on mainly these two characteristics.

#### **3.1 Static characteristics**

In fact, such as smart buildings, physical infrastructure or technical experimentations are some applications, where the network is stable i.e. static over the space, having several fixed components in the network is regular solution. The fixed parts

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

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

The characteristics of some applications include low cost, small size, low power consumption, robustness, flexibility, resiliency on errors and faults, autonomous mode of operation, and often privacy and security.

## **3.2 Dynamic characteristics**

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 consume too much power.

### *3.2.1 Ad-hoc network like MANET*

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 frequencies (30 MHz-5GHz).

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

**Figure 8** shows clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption

**Figure 6.** *Structure of static network.*

slot, all transmissions are considered to be corrupted, and the control packets involved in this collision have to be retransmitted in future time slots. Hence, when

Many of the characteristics may depend on the applications. In some of the applications, it might be acceptable or in some of the applications it might not be

Following are the common characteristics that need to be considered while using

a collision occurs, none of the involved nodes are aggregated to a cluster.

that much considered. So, few are the characteristics are common.

Let us see all above mentioned characteristics one by one in detail.

The consumption of Power limits for nodes with batteries. Many of the challenges of sensor networks revolve around the limited power resources. The size of the nodes limits the size of the battery. The software and hardware design needs to carefully consider the issues of efficient energy use. Specific power-management strategies are necessary for WSN nodes that are powered by non-rechargeable

It is mandatory to note the power eating features of the node in three components. They are the sensing circuitry, the digital processing unit, and the radio

The sensing circuitry, which consists of the environmental green sensors and the ADC, needs energy for bias currents, as well as amplification and analog filtering. A node's digital processing circuits are typically used for digital signal processing

Two-way communication through radio transceiver unit with other nodes and a remote base station is achieved through a network processor, which packetizes and

The key to accomplish a longer lifespan for WSN is to design with minimal power consumption of wireless sensor nodes, hence titled "low power". To reduce

of gathered data and implementation of the protocol stack.

encodes the data for robustness and security.

*3.2.2 Some common characteristics*

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

1.Power Efficiency

5.Data compression

2.Low power

4.Reliability

6. Scalability

7.Mobility

batteries.

transceiver unit.

**5. Low power**

**11**

**4. Power efficiency**

WSN for developing different applications.

3.Responsiveness, energy constraint

**Figure 7.** *Structure of ad-hoc networks.*

**Figure 8.** *Clustered-based wireless sensor network.*

reductions. The cluster formation phase, where all the dynamic nodes transfer a control packet focused to the sink node in order to be a portion of the cluster. Precisely, the lively active nodes in the managed that controlled area where control packet transmit with possibility 'τ' in each time slot. If there is only a single communication that is only one node transfer, the control packet is well received by the sink node, and the node that successfully transmitted this packet is considered to be already an adherent of a cluster.

As such, this node no longer transmits in the cluster formation phase. The remaining nodes continue this process until all the active nodes successfully transmit their control packet. If there are two or more transmissions in the same time

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

slot, all transmissions are considered to be corrupted, and the control packets involved in this collision have to be retransmitted in future time slots. Hence, when a collision occurs, none of the involved nodes are aggregated to a cluster.

#### *3.2.2 Some common characteristics*

Many of the characteristics may depend on the applications. In some of the applications, it might be acceptable or in some of the applications it might not be that much considered. So, few are the characteristics are common.

Following are the common characteristics that need to be considered while using WSN for developing different applications.

1.Power Efficiency

2.Low power

3.Responsiveness, energy constraint

4.Reliability

5.Data compression

6. Scalability

7.Mobility

Let us see all above mentioned characteristics one by one in detail.

#### **4. Power efficiency**

The consumption of Power limits for nodes with batteries. Many of the challenges of sensor networks revolve around the limited power resources. The size of the nodes limits the size of the battery. The software and hardware design needs to carefully consider the issues of efficient energy use. Specific power-management strategies are necessary for WSN nodes that are powered by non-rechargeable batteries.

It is mandatory to note the power eating features of the node in three components. They are the sensing circuitry, the digital processing unit, and the radio transceiver unit.

The sensing circuitry, which consists of the environmental green sensors and the ADC, needs energy for bias currents, as well as amplification and analog filtering.

A node's digital processing circuits are typically used for digital signal processing of gathered data and implementation of the protocol stack.

Two-way communication through radio transceiver unit with other nodes and a remote base station is achieved through a network processor, which packetizes and encodes the data for robustness and security.

#### **5. Low power**

The key to accomplish a longer lifespan for WSN is to design with minimal power consumption of wireless sensor nodes, hence titled "low power". To reduce the overall power consumption, low power WSN controls the lively active time or "awake time" of the devices (such as a radio or microcontroller) and limits the present draw when they are "sleeping." These networks accomplish this by changing the power setting modes of the devices, such as "always on", "standby", or "hibernation" modes. Depending upon the requirement, the nodes and its components may be used in different power setting modes. As the energy policy depends on the application; in some applications, it might be acceptable to turn off a subset of nodes in order to conserve energy while other applications require all nodes operating simultaneously. It helps to work WSN in low power mode.

#### **6. Responsiveness**

The sensor nodes need to become independent to work even in bad situations and portrait responsiveness. WSN works more efficiently if sensor nodes develop characteristics of responsiveness without explicit user and/or administrator action. If the network is more responsive, it yields more throughput and obviously increases the efficiency of the network.

node has to maintain connectivity with other sensors, also allowing connectivity to

2 Low power The key to achieving a longer lifetime for WSN is to design WSN that

3 Responsiveness Sensor networks need to become autonomous and exhibit responsiveness without explicit user or administrator action. 4 Reliability Reliability of the network increases the throughput of the WSN.

6 Scalability A good and adaptive (adapts the changes in the network topology) routing protocol makes the WSN more scalable. 7 Mobility This characteristic helps to maintain connectivity of mobile nodes with

minimizes power consumption of wireless sensor devices.

compression helps to reduce the stress of the node in WSN.

other sensors, also allowing connectivity to the Internet.

This characteristic insists to minimize the power eating property of the node. More power efficient network yields more effectiveness.

Nodes can use additional energy for computation and/or filtering. Data

All above mentioned characteristics have their own importance. **Table 1** is a

Let us see all above mentioned characteristics in detail along with some applications. Here, applications are included to explain how different characteristics are helpful while developing diverse applications. Keep in mind that these characteristics have their own importance while developing the applications. It's not at all necessary that every characteristic plays a vital role in every application. But, commonly all they help to increase the productivity, efficiency and throughput

Mainly, we are considering three applications while studying the above mentioned characteristics. They are viz. a. Health Monitoring System, b. Military

Here, we will see how above mentioned characteristics are important while developing the Health Monitoring System using WSN. The Bio-compatible wearable sensors allow vast amounts of data to be collected and mined for clinical trials, reducing the cost and inconvenience of regular visits to the physician. There are many aspects in which the health monitoring system works. Like, some advanced techniques are used to track diabetes using a WSN or A blood pressure sensor suitable for wireless biomedical applications. Patients can be tracked and monitored in normal or in emergency conditions at their homes, hospital rooms and also in Intensive Care Units (ICUs) [8]. To develop any of the applications in the Health Monitoring System, let us see

When WSN is used while developing military applications, again there is a need to think about the importance of above said characteristics. Video sensing is useful in various applications such as: military, environmental, healthcare, industries and surveillance of all its types [9]. To make an

how the above mentioned characteristics play a role.

briefing about all the characteristics one by one.

**Sr. No. Characteristics Importance of Characteristics**

Application and c. Security and surveillance.

a. **Health Monitoring System:**

b. **Military Application:**

**13**

while developing the application.

the Internet.

**Table 1.**

1 Power

5 Data

Efficiency

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

Compression

*A briefed view of characteristics.*

#### **7. Reliability**

WSNs involve a number of sensor nodes with limited processing, storage, and battery capabilities. The overall reliability of a WSN is enhanced by the reliability of the components of the node. If either of the components fails, the whole node fails. Each component/unit has associated reliability and defined in the software/hardware specification. There are numerous approaches to cut down the power consumption of WSN nodes (increases the network lifetime) and increase the reliability of the network (by improving the WSN quality of facility). As the reliability increases, obviously the capability of the network increases.

#### **8. Data compression**

While designing the WSN, it is necessary to reduce the amount of energy used for radio transmission, but nodes can use additional energy for computation and/or filtering. This can be fruitful if data is compressed.

#### **9. Scalability**

Scalability of routing protocols used in WSNs is an acute topic due to the tremendously high number of nodes and comparatively high node compactness. A good routing protocol has to be scalable and easily adaptive to the changes in the network topology. Performance of protocol must well as the network grows larger or as the workload increases.

#### **10. Mobility**

Mobility in wireless sensor networks is an element which directly influences the network performance. Indeed, with an architecture based on the IP stack, a mobile


#### **Table 1.**

*A briefed view of characteristics.*

node has to maintain connectivity with other sensors, also allowing connectivity to the Internet.

All above mentioned characteristics have their own importance. **Table 1** is a briefing about all the characteristics one by one.

Let us see all above mentioned characteristics in detail along with some applications. Here, applications are included to explain how different characteristics are helpful while developing diverse applications. Keep in mind that these characteristics have their own importance while developing the applications. It's not at all necessary that every characteristic plays a vital role in every application. But, commonly all they help to increase the productivity, efficiency and throughput while developing the application.

Mainly, we are considering three applications while studying the above mentioned characteristics. They are viz. a. Health Monitoring System, b. Military Application and c. Security and surveillance.

#### a. **Health Monitoring System:**

Here, we will see how above mentioned characteristics are important while developing the Health Monitoring System using WSN. The Bio-compatible wearable sensors allow vast amounts of data to be collected and mined for clinical trials, reducing the cost and inconvenience of regular visits to the physician. There are many aspects in which the health monitoring system works. Like, some advanced techniques are used to track diabetes using a WSN or A blood pressure sensor suitable for wireless biomedical applications. Patients can be tracked and monitored in normal or in emergency conditions at their homes, hospital rooms and also in Intensive Care Units (ICUs) [8]. To develop any of the applications in the Health Monitoring System, let us see how the above mentioned characteristics play a role.

#### b. **Military Application:**

When WSN is used while developing military applications, again there is a need to think about the importance of above said characteristics. Video sensing is useful in various applications such as: military, environmental, healthcare, industries and surveillance of all its types [9]. To make an

application efficient, it's not at all necessary to incorporate all characteristics. But, those who help to improve the throughput should get consideration while developing the application. As said above, this military application also has many aspects. WSNs can be used by the military for a number of purposes such as Monitoring or Tracking the Enemies, for Force Protection or for Vehicle Navigation systems for the military and so on.

**Sr. No.** **Characteristics Importance of**

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

3 Responsiveness Sensor networks

4 Reliability Reliability of the

**15**

**Characteristics**

wireless sensor devices.

need to become autonomous and exhibit responsiveness without explicit user or administrator action.

network increases the throughput of the WSN.

**Health Monitoring System**

cannot put the sensor in sleep mode as the sensor has to collect reading continuously in either Diabetes Monitoring System or BP Monitoring System. But the transceiver unit can be on sleep mode when there is no transmission or receiving of data.

To develop a Health Monitoring System, sensor nodes must be responsive to collect data regularly without

fail. Nodes have to work autonomously.

In account of correctness of reading in case of either application of the Health Monitoring System, reliability characteristics must be reflected

while implementing. To detect the sugar level or to monitor BP, the nodes must be reliable. Nodes must read all the readings correctly and reliably. Every component and unit must be capable of handling the unfortunate situations.

**Military Application**

achieve this goal, all required nodes and their components have to work continuously. This characteristic cannot be fulfilled in case of many military applications as we cannot put nodes in sleep or in hibernate mode.

In Military Application, sensor nodes must be responsive to collect data frequently without fail. To be responsive, to monitor the actions of the enemy, the network has to work

independently in case of any failure.

To increase the efficacy, all military applications must be implemented

consideration of reliability of sensor networks. Reliability can be increased here by developing nodes who support low power consumption.

with

**Security and surveillance**

Here also sensor nodes must be responsive to collect data repeatedly without fail. If the network is not responding continuously, then it will become difficult to give required security in current application.

With the characteristic reliability, the application of security and surveillance provides more security which is the objective for development of this application. Reliable network supports the security application in case of failure of any of the components or nodes, the whole network must give the required throughput.
