19-11-2012, 06:03 PM
Implementation of Energy Efficient Hierarchical Based Routing Protocol On Wireless Sensor Network
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ABSTRACT
Wireless sensor networks (WSNs) are being increasingly deployed for various applications such as
object tracking and monitoring, precision agriculture, controlling nuclear reactors, detecting seismic
activities, security and surveillance, navigational activities, industrial automation, and so on. The
main purpose of such networks is to gather information from the environments and deliver the same
to the applications. The smartness in functioning of smart environments rely primarily on gathering
sensory data through WSNs.
The sensor nodes are typically resource deficient with energy being the most critical of all the
resources. The nodes in a WSN are connected typically to a powerful controlling node called the
base station. The base station is generally assumed to be connected to a stable power source and is
not considered energy deficient, whereas all other nodes are battery powered. So, efficient use of
energy resources in sensor nodes could extend the lifetime of the WSNs. The activity of sensing
does not require much energy, it is the communication required for the delivery of the sensed data
which causes most drainage of a sensor’s battery. Therefore, the issue of energy saving is considered
primarily in transmission and dissemination of data in sensor networks.
Using hierarchical based routing protocol reduces not only the congestion but also leads to
better utilization of energy resources as individual nodes can operate with low transmission power.
In cluster based routing protocols the main issue to be considered is that the nodes near the base
station have to bear with the responsibility of delivery of data packets of all the nodes in the network.
INTRODUCTION
A homogeneous WSN is composed of tiny, resource-constrained devices, using the same
platform and having the same hardware capabilities. The functionality of a homogeneous WSN
serves mainly the purpose of gathering the sensed data and sending it to a central location. The
typical research questions focus on prolonging the lifetime of the network, by designing energyefficient
protocols which distribute the communication overhead evenly among the sensor nodes. A
heterogeneous WSN employs a range of different devices, which are able to cooperate in order to
achieve a global goal by combining the individual capabilities of the nodes. Small and cheap sensor
nodes are deployed with high density and easily attached to people or objects moving in the
environment, while the more powerful nodes are able to provide persistent data storage, intensive
processing and actuation. In such a network, the objective is to distribute the workload depending on
the capabilities of the nodes.
The sensor nodes are typically resource deficient with energy being the most critical of all the
resources. The nodes in a WSN are connected typically to a powerful controlling node called the
base station. The base station is generally assumed to be connected to a stable power source and is
not considered energy deficient, whereas all other nodes are battery powered. So, efficient use of
energy resources in sensor nodes could extend the lifetime of the WSNs. The activity of sensing does
not require much energy, it is the communication required for the delivery of the sensed data which
causes most drainage of a sensor’s battery. Therefore, the issue of energy saving is considered
primarily in transmission and dissemination of data in sensor networks.
APPLICATION OF WIRELESS SENSOR NETWORK
Wireless Sensor Networks (WSN) offers a rich, multi-disciplinary area of research, in which
a number of tools and concepts can be applied to address a whole diverse set of applications. Sensor networks may consist of many different types of sensors such as magnetic, thermal, visual, seismic,
and infrared and radar, which are able to monitor a wide variety of conditions. These sensor nodes
can be put for continuous sensing, location sensing, and motion sensing and event detection. The
idea of micro-sensing and wireless connection of these sensor nodes promises many new application
areas. A few examples of their applications are as follows:
AREA MONITORING APPLICATIONS
Area monitoring is a very common application of WSNs. In area monitoring, the WSN is
Deployed over a region where some physical activity or phenomenon is to be monitored. When the
sensors detect the event being monitored (sound, vibration), the event is re-ported to the base station,
which then takes appropriate action (e.g., send a message on the internet or to a satellite). Similarly,
wireless sensor networks can be deployed in security systems to detect motion of the unwanted,
traffic control system to detect the presence of high-speed vehicles. Also WSNs finds huge
application in military area for battlefield surveillance, monitoring friendly forces, equipment and
ammunition, reconnaissance of opposing forces and terrain, targeting and battle damage assessment.
Leach Protocols
LEACH [3] is an adaptive clustering routing protocol proposed by Wendi B. Heinzelman, et
al. The implementation process of LEACH [3] includes many rounds. Each round consists of the
setup phase and the steady data transmission phase. In the set-up phase, the cluster head nodes are
randomly selected from all the sensor nodes and several clusters are constructed dynamically. In the
steady data transmission phase, member nodes in every cluster send data to their own cluster head,
the cluster head compresses the data that received from member nodes and sends the compressed
data to the sink node. LEACH [3] protocol periodically elects the cluster head nodes and reestablishes
the clusters according to a round time, which ensures energy dissipation of each node in
the network is relatively evenly. Considering that the sensors are resource constraint, a lot of scope
for improvements was there. LEACH [3] is another protocol in line to throw some light on the same
issues and propose some more improvements. The basic idea employed in LEACH [3] is cut down
the overhead by reduce volume of data reportage. LEACH [3] is an energy efficient, aggregation
protocol. It includes cluster formation and local processing to reduce global communication by
collecting the packets of all the nodes in the cluster in one place and aggregating the information
contained. The randomized rotation of the cluster-heads helps in implementing the load sharing
property.