Energy Saving Hierarchical Routing Protocol in WSN

*C. Parvathi and Suresha Talanki*

#### **Abstract**

The area of Wireless Sensor Networks (WSN) bring a new era of connected ondemand embedding systems which are mostly resource constrained. Despite of having design and operational challenges in real-time, WSN is currently being deployed for wide range of applications where traditional networking systems are most of time unfeasible. The prime focus of the study is to realize the significance of energy efficient routing in WSN. The core motivation is derived by addressing energy problems of WSN. An extensive analysis drawn from reviewing literatures, clearly shows that very few studies incorporated optimization towards modeling the routing schema. This chapter introduces a methodology consisting of three different types of analytical modeling where two of them focus on energy efficient clustering and another one is integrated to attain higher degree of security during data aggregation. The chapter basically provides an insight into the background of the problem which is related with the energy and security in WSN and also further provides preliminary information regarding the research overview. Further the study performs a thorough investigation on existing literatures to extract the open research problem. It basically highlights the gap which still exists and does not meet the requirements of proper energy and security demands. Literature survey on hierarchical protocols of WSN and their basic characteristics towards energy conservation is performed.

**Keywords:** energy, hierarchical, QoS, routing protocol, WSN (wireless sensor network)

#### **1. Introduction**

#### **1.1 Preamble**

In the era of Wireless Sensor network-(WSN), an energy-aware mechanism especially routing protocols, are the major concerns in the research area. This chapter presents a brief discussion about the major power consumption factors that causes the node to run out of their energy due to which WSN becomes nonfunctional. In addition, this chapter also discusses various existing hierarchical routing mechanisms introduced for energy saving goal in WSN.

Factors Associated to Energy Consumption in WSN This section demonstrates the fundamental characteristics and necessary aspects of WSN in order to understand the cause, factor, and requirements for designing energy saving routing mechanism. The literature review is the research method used in this chapter which is a more relevant method than ever.

#### **1.2 Background of WSN**

Before discussing about the energy consumption related factors, it is essential to explain about the background of WSN. The concept of WSN is not new, and since the last 10 decades, it has got lots of popularity among the researchers. However, WSN has the vast potential of sensor network to facilitate real-time and automated services with very less human interaction property. The deployment of WSNs, have attracted various working field of real-time applications such as in (i) Military application: for target localization and for tracking war event, (ii) Medical application: for healthcare monitoring and real-time medical data sharing for diagnosing, (iii) Industrial applications: for monitoring robotic system, the security system, and surveillance system, (iv) Environmental application: for monitoring the environmental factor and events, like this there are many more internal and external application where the concept of WSN are used. There are different technical issues for different applications that the researchers are still working for developing an efficient solution [1, 2].

These technical issues arise due to the constraint nature of WSN that includes many limited properties such as, low-cost and limited battery-operated sensors nodes, limited connectivity & coverage range and less processing and limited transmission capacity. The Routing mechanisms in WSNs are responsible for constructing the paths among the targeted nodes and also to perform multihop communication between nodes in a network for which WSN requires an effective and feasible technique to perform energy efficient routing operation for reliable communication, transmission & data processing [3].

• Energy Utilization: Energy utilization in WSN is defined as a total difference between the initial power and the final power. The following is the numerical expression that can be used to define energy-utilization mathematically:

$$
\begin{aligned}
\text{\(\pi\)} & \text{consumption} = \eta \\
& \text{\(\pi\)} \\
& \text{\(\pi\)} & \text{\(\pi\)} \\
& \text{\(\pi\)} & \text{\(\pi\)}
\end{aligned}
\tag{1}
$$

**3. Energy consumption issues**

*Power consumption by sensor node in different states.*

*Energy Saving Hierarchical Routing Protocol in WSN DOI: http://dx.doi.org/10.5772/intechopen.93595*

**Figure 1.**

• Dynamic topology

• Data redundancy

• Long Coverage

• Packet overhead

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• Environmental factor

• Data collection process

• Intermediate node malfunctioning

and practitioners for improving WSN lifecycle

• Setting unwanted sensors into sleep mode

using efficient energy to their neighbor nodes

The energy utilization issue in WSNs is a fundamental problem which is directly associated to its lifetime. Therefore, it becomes the primary goal to be solved while designing WSN architecture. In WSN, the energy supplied to the sensor is usually battery-powered, and the sensor cannot reach to the level of long-term operation without recharging [6]. Also, sensors are typically used in remote or harsh environments, such as battlefields, where it is not possible to charge or replace the battery from all sensor's nodes. Furthermore, sensor network lifetime having a strong dependency on the other intermediate nodes because, as failure of some intermediate sensor nodes lead to significant topology changes and that require re-routing process for communication and data-packets transmission in the network. The following are the main factors that

cause complexities while designing energy efficient mechanism in WSN [7]:

The following are some steps which have been introduced by several researchers

• Modifying transmission range so that the sensor node can transmit the data

• Limited availability of power in the sensor node

£ utilization <sup>¼</sup> <sup>τ</sup> consumption‐<sup>τ</sup> consumption

The above Eq. (1) illustrates the mathematical definition of £ utilization- (energy-consumption) where ι consumption is the initial energy depletion factor, and τ consumption is the total energy depletion factor. The ι consumption is calculated using ɳ (residual energy before performing any operation), and τ consumption is calculated using the addition of total energy consumed in operation of σ (sensing), γ (data forwarding & receiving) and μ (data processing).

#### **2. Analysis of power depletion by sensor nodes**

In WSN a single sensor node consists of four components: fixed limited battery, a sensing module, wireless module and data processing module. The energy consumed in data processing and sensing operation is quite low whereas the maximum energy is absorbed in the communication layer of the wireless module.

In the wireless communication operation, the sensor node responsible for data forwarding and data receiving which takes very high energy for communication process in the sensor nodes deployed in the network. **Figure 1** displays the energy consumption ratio with various sensors states [4, 5].

*Energy Saving Hierarchical Routing Protocol in WSN DOI: http://dx.doi.org/10.5772/intechopen.93595*

**Figure 1.** *Power consumption by sensor node in different states.*

### **3. Energy consumption issues**

The energy utilization issue in WSNs is a fundamental problem which is directly associated to its lifetime. Therefore, it becomes the primary goal to be solved while designing WSN architecture. In WSN, the energy supplied to the sensor is usually battery-powered, and the sensor cannot reach to the level of long-term operation without recharging [6]. Also, sensors are typically used in remote or harsh environments, such as battlefields, where it is not possible to charge or replace the battery from all sensor's nodes. Furthermore, sensor network lifetime having a strong dependency on the other intermediate nodes because, as failure of some intermediate sensor nodes lead to significant topology changes and that require re-routing process for communication and data-packets transmission in the network. The following are the main factors that cause complexities while designing energy efficient mechanism in WSN [7]:


The following are some steps which have been introduced by several researchers and practitioners for improving WSN lifecycle


• Deployment of sensors in a hierarchical network so that cluster heads can be used to aggregate data and reduce the amount of information sent up to the sink

i. **Proactive routing approach:** In this, the protocols have to maintain a routing information table before initiating the path discovery phase

ii. **Reactive routing approach:** In this protocol, the initialization of the path discovery process for data exchange is based on the requirement

iii. **Hybrid routing approach:** In this, both reactive and proactive routing

i. **Multi-path-based routing approach:** Multi-path protocol for routing operation is an alternate process in which protocol selects multi-path to deliver data from source to destination. This is mainly designed to overcome the limitation of single route data transmission in order to

ii. **Query-based routing approach:** Here, the target node broadcasts a query message between the nodes. After receiving the query message, the node replies to the target node with a query matching message. After matching the query from both side nodes, then it initiates a data

iii. **QoS based routing approach:** In this protocol, the routing is selected on the basis of QoS parameters such that the network must ensure the efficient load balance between energy consumption and data quality

i. **Flat based routing approach:** In this routing approach each node has a similar role in which sharing of data packets is performed through

ii. **Hierarchical based routing approach:** In this approach, routing is performed in an efficient way to utilize low energy as much as possible to increase the lifetime of WSN. In this, the nodes with higher energy

forwarding and processing, whereas the nodes with lower energy are selected as a normal node to sense events and collect raw data.

initialized based on the estimation of sensor location. Also, in order to preserve node energy, some nodes are switched into sleep mode when no events and activities are found at the location of such nodes.

are prioritized to form a cluster that are responsible for data

iii. **Location-based routing approach:** In this approach, routes are

The above Sections 1 and 2, briefly introduced the background of WSN and its fundamental problem (energy consumption) and further introduced the routing process involved in WSN. The proposed system focuses on hierarchical routing protocols to make the WSN active longer. The next section presents an extensive

and this is also known as table-driven routing approach.

• **The routing protocol based on the protocol operation includes:**

achieve more reliability and load balancing.

exchange process between them.

(bandwidth, delay, reliability, etc.)

several intermediate nodes.

analysis of the existing hierarchical routing protocol.

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• **The routing protocol based on the Network Structure includes:**

of route demand.

*Energy Saving Hierarchical Routing Protocol in WSN DOI: http://dx.doi.org/10.5772/intechopen.93595*

is used in the combined form.

