Design Issues and Applications of Wireless Sensor Network

@ IJTSRD | Available Online @ www.ijtsrd.com | Volume – 1 | Issue – 6 | Sep - Oct 2017 Page: 798
ISSN No: 2456 - 6470 | www.ijtsrd.com | Volume - 1 | Issue – 6
International Journal of Trend in Scientific
Research and Development (IJTSRD)
International Open Access Journal
Design Issues and Applications of Wireless Sensor Network
G. Swarnalatha
Assistant Professor, Department of Commerce with
Computer Applications, Dr.SNS Rajalakshmi College
of Arts and Science, Coimbatore, TamilNadu, India
R. Srilalitha
PG Student, Department of Commerce with Computer
Applications, Dr.SNS Rajalakshmi College of Arts
and Science, Coimbatore, TamilNadu, India
ABSTRACT
Efficient design and implementation of wireless
sensor networks has become a hot area of research in
recent years, due to the vast potential of sensor
networks to enable applications that connect the
physical world to the virtual world. By networking
large numbers of tiny sensor nodes, it is possible to
obtain data about physical phenomena that was
difficult or impossible to obtain in more conventional
ways. In future as advances in micro-fabrication
technology allow the cost of manufacturing sensor
nodes to continue to drop, increasing deployments of
wireless sensor networks are expected, with the
networks eventually growing to large numbers of
nodes. Potential applications for such large-scale
wireless sensor networks exist in a variety of fields,
including medical monitoring, environmental
monitoring, surveillance, home security, military
operations, and industrial machine monitoring etc.
Fig (a) A Typical Sensor Network Architecture
INTRODUCTION
Wireless sensor network (WSN)[5] are highly
distributed networks of small, lightweight wireless
nodes, deployed in large numbers to monitor the
environment or system by the measurement of
physical parameters such as temperature, pressure
humidity, sound, vibration, pollutants, and
collectively relay their sensed data to the sink node.
Each node in the networks are connected to each
other. Each sensor node in the network consists of
three subsystems:
The sensor subsystem is used to sense the
environment. The processing subsystem performs the
local computations on the sensed data and the
communication subsystem is responsible for sharing
the sensed data with the neighboring sensor nodes.
The sensor subsystem senses the data in the
environment and the processing subsystem processes
the sensed data where as the communication
subsystem sends the aggregated data to the sink node.
A sensor network consists of different types of
sensors such as seismic, thermal, visual, and infrared.
The size of a sensor node may vary from micro to
macro and the cost varies from one to few hundred
dollars. The sensor nodes communicate through
wireless with in the short distance. The competence of
each individual sensor node is limited and the
comprehensive power of the entire network is
adequate for the required task. The sensor nodes are
organized themselves autonomously into a wireless
network. Sensor nodes operated in the battery power
expected to sense for a long time. In most of the

International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470
situations, the battery cannot be recharged or
replaced.
Wireless Sensor Networks (WSN) are intended for
monitoring an environment. The main task of a
wireless sensor node is to sense and collect data from
a certain domain, process them and transmit it to the
sink where the application lies.
Sensor networks have emerged as a promising tool for
monitoring (and possibly actuating) the physical
world, utilizing self-organizing networks of battery-
powered wireless sensors that can sense, process and
communicate. In sensor networks, energy is a critical
resource, while applications exhibit a limited set of
characteristics. Thus, there is both a need and an
opportunity to optimize the network architecture for
the applications in order to minimize resource
consumed. The requirements and limitations of sensor
networks make their architecture and protocols both
challenging and divergent from the needs of
traditional internet architecture.
A sensor network [1][3] is a network of many tiny
disposable low power devices, called nodes, which
are spatially distributed in order to perform an
application-oriented global task. These nodes form a
network by communicating with each other either
directly or through other nodes. One or more nodes
among them will serve as sink(s) that are capable of
communicating with the user either directly or
through the existing wired networks. The primary
component of the network is the sensor, essential for
monitoring real world physical conditions such as
sound, temperature, humidity, intensity, vibration,
pressure, motion, pollutants etc. at different locations.
IMPORTANT REQUIREMENTS OF A WSN
 Use of a large number of sensors
 Attachment of stationary sensors
 Low energy consumption
 Self organization capability
 Collaborative signal processing
 Querying ability
DESIGN ISSUES IN WIRELESS SENSOR
NETWORK
Despite the innumerable applications of WSNs, these
networks have several restrictions, such as limited
energy supply, limited computing power, and limited
bandwidth of the wireless links connecting sensor
nodes. One of the main goals of WSNs is to carry out
data communication while trying to prolong the
lifetime of the network and prevent connectivity
degradation by employing aggressive energy
management techniques. The design of routing
protocols in WSNs [5][6] is influenced by many
challenging factors. These factors must be overcome
before efficient communication can be achieved in
WSNs. In the following, we summarize some of the
routing challenges and design issues that affect the
routing process in WSNs.
Node deployment
Node deployment [4] in WSNs is application-
dependent and can be either manual (deterministic) or
randomized. In manual deployment, the sensors are
manually placed and data is routed through
predetermined paths. However, in random node
deployment, the sensor nodes are scattered randomly,
creating an ad hoc routing infrastructure. If the
resultant distribution of nodes is not uniform, optimal
clustering becomes necessary to allow connectivity
and enable energy-efficient network operation. Inter
sensor communication is normally within short
transmission ranges due to energy and bandwidth
limitations. Therefore, it is most likely that a route
will consist of multiple wireless hops.
Energy consumption without losing accuracy
Sensor nodes can use up their limited supply of
energy performing computations and transmitting
information in a wireless environment. As such,
energy-conserving forms of communication and
computation are essential. Sensor node lifetime shows
a strong dependence on battery lifetime. In a multihop
WSN, each node plays a dual role as data sender and
data router. The malfunctioning of some sensor nodes
due to power failure can cause significant topological
changes, and might require rerouting of packets and
reorganization of the network.
Data reporting method
Data reporting [2] in WSNs is application-dependent
and also depends on the time criticality of the data.
Data reporting can be categorized as either time-
driven, event driven, query-driven, or a hybrid of all
these methods. The time-driven delivery method is
suitable for applications that require periodic data
monitoring. As such, sensor nodes will periodically
switch on their sensors and transmitters, sense the
environment, and transmit the data of interest at
constant periodic time intervals. In event-driven and

query-driven methods, sensor nodes react
immediately to sudden and drastic changes in the
value of a sensed attribute due to the occurrence of a
certain event, or respond to a query generated by the
BS or another node in the network. As such, these are
well suited to time-critical applications. A
combination of the previous methods is also possible.
The routing protocol is highly influenced by the data
reporting method in terms of energy consumption and
route calculations.
Node/link heterogeneity
In many studies, all sensor nodes were assumed to be
homogeneous (i.e., have equal capacity in terms of
computation, communication, and power). However,
depending on the application a sensor node can have a
different role or capability. The existence of a
heterogeneous set of sensors raises many technical
issues related to data routing. For example, some
applications might require a diverse mixture of
sensors for monitoring temperature, pressure, and
humidity of the surrounding environment, detecting
motion via acoustic signatures, and capturing images
or video tracking of moving objects. Either these
special sensors can be deployed independently or the
different functionalities can be included in the same
sensor nodes. Even data reading and reporting can be
generated from these sensors at different rates, subject
to diverse QoS constraints, and can follow multiple
data reporting models. For example, hierarchical
protocols designate a cluster head node different from
the normal sensors. These cluster heads can be chosen
from the deployed sensors or be more powerful than
other sensor nodes in terms of energy, bandwidth, and
memory. Hence, the burden of transmission to the
Base Station (BS) is handled by the set of cluster
heads.
Fault tolerance
Some sensor nodes [11]may fail or be blocked due to
lack of power, physical damage, or environmental
interference. The failure of sensor nodes should not
affect the overall task of the sensor network. If many
nodes fail, medium access control (MAC) and routing
protocols must accommodate formation of new links
and routes to the data collection BSs. This may
require actively adjusting transmit powers and
signaling rates on the existing links to reduce energy
consumption, or rerouting packets through regions of
the network where more energy is available.
Therefore, multiple levels of redundancy may be
needed in a fault-tolerant sensor network.
Scalability
The number of sensor nodes deployed in the sensing
area may be on the order of hundreds or thousands, or
more. Any routing scheme must be able to work with
this huge number of sensor nodes. In addition, sensor
network routing protocols[12] should be scalable
enough to respond to events in the environment. Until
an event occurs, most sensors can remain in the sleep
state, with data from the few remaining sensors
providing coarse quality.
Network dynamics
In many studies, sensor nodes are assumed to be
fixed. However, in many applications both the BS or
sensor nodes can be mobile. As such, routing
messages from or to moving nodes is more
challenging since route and topology stability become
important issues, in addition to energy, bandwidth,
and so forth. Moreover, the phenomenon can be
mobile (e.g., a target detection/ tracking application).
On the other hand, sensing fixed events allows the
network to work in a reactive mode (i.e., generating
traffic when reporting), while dynamic events in most
applications require periodic reporting to the BS.
Transmission media
In a multihop sensor network [30], communicating
nodes are linked by a wireless medium. The
traditional problems associated with a wireless
channel (e.g., fading, high error rate) may also affect
the operation of the sensor network. In general, the
required bandwidth of sensor data will be low, on the
order of 1–100 kb/s. Related to the transmission
media is the design of MAC. One approach to MAC
design for sensor networks is to use time-division
multiple access (TDMA)-based protocols that
conserve more energy than contention-based
protocols like carrier sense multiple access (CSMA)
(e.g., IEEE 802.11) [10]. Bluetooth technology can
also be used.
Connectivity
High node density in sensor networks precludes them
from being completely isolated from each other.
Therefore, sensor nodes are expected to be highly
connected. This, however, may not prevent the
network topology from being variable and the

network size from shrinking due to sensor node
failures. In addition, connectivity depends on the
possibly random distribution of nodes.
Coverage
In WSNs, each sensor node obtains a certain view of
the environment. A given sensor’s view of the
environment is limited in both range and accuracy and
it can only cover a limited physical area of the
environment. Hence, area coverage is also an
important design parameter in WSNs.
Data aggregation
Since sensor nodes may generate significant
redundant data, similar packets from multiple nodes
can be aggregated[6] to reduce the number of
transmissions. Data aggregation is the combination of
data from different sources according to a certain
aggregation function (e.g., duplicate suppression,
minima, maxima, and average). This technique has
been used to achieve energy efficiency and data
transfer optimization in a number of routing protocols.
Signal processing methods can also be used for data
aggregation. In this case, it is referred to as data
fusion[6][10] where a node is capable of producing a
more accurate output signal by using some techniques
such as beam forming to combine the incoming
signals and reducing the noise in these signals.
Quality of service
In some applications, data should be delivered within
a certain period of time from the moment it is sensed,
or it will be useless. Therefore, bounded latency for
data delivery is another condition for time-constrained
applications. However, in many applications,
conservation of energy, which is directly related to
network lifetime, is considered relatively more
important than the quality of data sent. As energy is
depleted, the network may be required to reduce the
quality of results in order to reduce energy dissipation
in the nodes and hence lengthen the total network
lifetime. Hence, energy-aware routing protocols are
required to capture this requirement.
FEATURES OF WIRELESS SENSOR
NETWORK
Protocol design for sensor networks must account for
the properties of ad hoc networks, including the
following:
 Lifetime constraints imposed by the limited
energy supplies of the nodes in the network.
 Unreliable communication due to the wireless
medium.
 Need for self-configuration, requiring little or
no human intervention.
PROTOCOLS USED IN WSN
Routing protocols [1] can be classified into
 Multipath-based protocol
 Query-based protocol
 Negotiation- based protocol
 QoS-based, or coherent-based protocol
TABLE I: ROUTING PROTOCOLS FOR WSNS
Category Representative Protocols
Location-based
Protocols
MECN, SMECN, GAF, GEAR,
Span, TBF, BVGF, GeRaF
Data-centric
Protocols
SPIN, Directed Diffusion, Rumor
Routing, COUGAR,ACQUIRE,
EAD, Information-Directed
Routing(DD), Gradient-Based
Routing(GBR), Energy-aware
Routing, Information-Directed
Routing, Quorum-Based
Information Dissemination, Home
Agent Based Information
Dissemination
Hierarchical
Protocols
LEACH, PEGASIS, HEED, TEEN,
APTEEN
Mobility-based
Protocols
SEAD, TTDD, Joint Mobility and
Routing, Data MULES Dynamic
Proxy Tree-Base Data
Dissemination
Heterogeneity-
based Protocols
IDSQ, CADR, CHR
Multipath-
based Protocols
Sensor-Disjoint Multipath, Braided
Multipath, N-to-1
Multipath Discovery
QoS-based
protocols
SAR, SPEED, Energy-aware
routing

APPLICATIONS OF WIRELESS SENSOR
NETWORK
Sensor networks may consist of many different types
of sensors[4] such as seismic, low sampling rate
magnetic, visual, thermal, infra-red, acoustic and
radar, which are able to monitor a wide variety of
ambient conditions. Sensor nodes can be used for
continuous sensing, event detection, event ID, and
local control of actuators. The concept of micro
sensing and wireless connection of these nodes
promise many new application areas. The applications
are categorized into military, environmental, health,
home, and other commercial areas.
Military Applications
Wireless sensor networks can be an integral part of
military command,[2] control, communication,
computing, intelligence, surveillance and targeting
(C4ISRT) systems. The rapid deployment, fault
tolerance and self organization characteristics of
sensor networks make them a very promising sensing
technique for military (C4ISRT). Since sensor
networks are based on dense deployment of
disposable and low cost sensor nodes, destruction of
some nodes by hostile actions does not affect military
applications as much as the destruction of traditional
sensor, which makes sensor networks concept a better
approach for battlefield. Various military applications
of sensor networks are monitoring friendly forces,
equipments and ammunition, biological and chemical
attack detection and reconnaissance.
Environmental Applications
Some environmental applications[14] of sensor
network include tracking the movement of birds,
small animals and insects, monitoring environmental
conditions that affect crops and livestock ,irrigation;
macro instruments for large scale earth monitoring
and planetary exploration, chemical/biological
detection, precision agriculture, biological, earth and
environmental monitoring in marine, soil and
atmosphere, forest fire detection meteorological and
geo physical research, flood detection, bio complexity
mapping of the environment and pollution study.
Health Application
Some of the applications are providing interfaces for
the disabled, integrated patient monitoring,
diagnostics, drug administration in hospital,
monitoring the movements and internal process of
insects[33] or other small animals, telemonitoring of
human physiological data, and tracking and
monitoring doctors and patients inside a hospital.
Home Applications
A technology advances, in home automation smart
sensor nodes and actuators can be buried appliances
such as vacuum cleaners, microwave ovens,
refrigerators and VCRs. These sensor nodes inside the
domestic devices can interact with each other and
with a external network via the internet or satellite.
They allow end users to manage home devices locally
and remotely more easily.
Other Commercial applications
Some of the commercial applications[4] are
monitoring material fatigue, building virtual
keyboards, managing inventory, monitoring product
quality, constructing smart office spaces,
environmental control in office buildings, robot
control and guidance in automatic manufacturing
environment, interactive toys and museums, factory
process control and automation, monitoring disaster
area, smart structures with sensor nodes embedded
inside, machine diagnosis, transportation, factory
instrumentation, local control of actuators, detecting
and monitoring car thefts, vehicle detection and
tracking, instrumentation of semiconductor
processing chambers, rotating machinery, wind
tunnels and anechoic chambers.
CONCLUSION
Wireless Sensor nodes are densely deployed either
very close or directly inside the phenomenon to be
observed. Therefore, they usually work unattended in
remote geographic areas. . In most of the sensor
network applications replenishment of power
resources is nearly impossible. Another important
factor that influences the consumption of more power
in sensor networks is that each sensor node consumes
power not only for sensing but also for processing the
sensed data and transmitting/receiving them to/from
neighbors. WSN is the one of the most challenging
task for researchers nowadays. Some important
factors should be taken into account when designing
an energy efficient routing protocol for WSN.

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