1. Wireless Sensor Networks
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A wireless sensor network (WSN) consists of spatially distributed autonomous sensors
to monitor physical or environmental conditions, such as temperature, sound, pressure, etc. and
to cooperatively pass their data through the network to a main location. The more modern
networks are bi-directional, also enabling control of sensor activity. The development of wireless
sensor networks was motivated by military applications such as battlefield surveillance; today
such networks are used in many industrial and consumer applications, such as industrial process
monitoring and control, machine health monitoring, and so on.
Wireless Sensor Networks have recently emerged as a premier research topic. They have
great long term economic potential, ability to transform lives, and pose many system-building
challenges. Wireless sensor networks also pose a number of new conceptual and optimization
problems, such as deployment, location and tracking, are fundamental issues, in that many
applications rely on them for needed information. Coverage basically, answers the questions
about quality of service (surveillance) that can be provided by a particular sensor network.
The integration of several types of sensors such as seismic, optical, acoustic etc. in one
network platform and the study of the overall coverage of the system also presents many
interesting challenges. With the refinement of energy harvesting techniques that can gather
useful energy from blasts of radio energy, vibrations and the like, self-powered circuitry is a real
possibility, with networks of millions of nodes, deployed through injections, paintbrushes and
aircraft. Also, the introduction of an additional type of sensor node allowing the network to self-
organize by embedding adaptive and smart algorithms. While on the other hand, the use of
adaptive power control in IP networks that utilizes reactive routing protocols and sleep-mode
operation, more powerful mobile agents, QoS (Quality of Service) to guarantee delivery,
robustness, security mechanisms, and fault-tolerance.
Wireless sensors have become an excellent tool for military applications involving
intrusion detection, perimeter monitoring, and information gathering and smart logistics support
in an unknown deployed area. Other applications include sensor-based personal health monitor,
location detection with sensor networks and movement detection.
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The WSN is built of "nodes" from a few to several hundreds or even thousands, where
each node is connected to one (or sometimes several) sensors. Each such sensor network node
has typically several parts: a radio transceiver with an internal antenna or connection to an
external antenna, a microcontroller, an electronic circuit for interfacing with the sensors and an
energy source, usually a battery or an embedded form of energy harvesting.
A sensor node might vary in size from that of a shoebox down to the size of a grain of
dust, although functioning "motes" of genuine microscopic dimensions have yet to be created.
The cost of sensor nodes is similarly variable, ranging from a few to hundreds of dollars,
depending on the complexity of the individual sensor nodes. Size and cost constraints on sensor
nodes result in corresponding constraints on resources such as energy, memory, computational
speed and communications bandwidth. The topology of the WSNs can vary from a simple star
network to an advanced multi-hop wireless mesh network. The propagation technique between
the hops of the network can be routing or flooding.
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I.F. Akyildiz, W. Su, Y. Sankarasubramaniam, and E. Cayirci; ―Wireless sensor networks:
a survey, Computer Networks 38 (2002) 393–422, 2002 Elsevier Science B.V [1,10].This paper
describes the concept of sensor networks, which has been made viable by the convergence of
micro electro-mechanical systems technology, wireless communications and digital electronics.
First, the sensing tasks and the potential sensor networks applications are explored, and a review
of factors influencing the design of sensor networks is provided. Then, the communication
architecture for sensor networks is outlined, and the algorithms and protocols developed for each
layer in the literature are explored. Open research issues for the realization of sensor networks
are also discussed.
Wei Ye, John Heidemann, Deborah Estrin, ―An Energy-Efficient MAC Protocol for
Wireless Sensor Networks‖ Infocom 2002 . This paper proposes S-MAC, a medium-access
control (MAC) protocol designed for wireless sensor networks. We expect sensor networks to be
deployed in an ad hoc fashion, with individual nodes remaining largely inactive for long periods
of time, but then becoming suddenly active when something is detected. These characteristics of
sensor networks and applications motivate a MAC that is different from traditional wireless. S-
MAC uses three novel techniques to reduce energy consumption and support self-configuration.
To reduce energy consumption in listening to an idle channel, nodes periodically sleep.
Neighboring nodes form virtual clusters to auto-synchronize on sleep schedules.
Yong Wang, Margaret Martonosi, and Li-Shiuan Peh, ―Supervised Learning in Sensor
Networks: New Approaches with Routing, Reliability Optimizations‖ . Routing in sensor
networks maintains information on neighbour states and potentially many other factors in order
to make informed decisions. Challenges arise both in (a) performing accurate and adaptive
information discovery and (b) processing/analyzing the gathered data to extract useful features
and correlations. To address such challenges, the authors explore using supervised learning
techniques to make informed decisions in the context of wireless sensor networks.
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Xiaonan Wang, Deguang proposed a paper on all-IP WSN architecture. This architecture was
based on a hierarchical address and gateway trees. This system performs on the routing operation
without a route discovery and using a home address, mobile node is easily identified. Using
IPV6 address, Physician can easily identify the location of patient. And the proposed project
based on the simulation.
Anuj.C.K, Lekshmi.S proposed a paper on wireless monitoring system using ARM
microcontroller. Using ARM microcontroller, the patients’ physical parameter like ECG, oxygen
level, blood pressure are measured.
A.AL.Marakeby proposed a paper on WSN technology by using camera. The WSN technology
progress was improved by allowing the camera connect to WSN node for transferring video and
image. The high demand of bandwidth was the problem in video and image transmission. At
node side, WSN node capturing images was scrutinize. The low computational power and
memory resource of camera node was optimized by using image processing algorithm.
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The architecture of WSN consists of sensor microcontroller unit antenna and transmitter
& receiver of the system. sensor and control units are connected to the battery for required power
supply voltage sensor sense the physical environment and send the input to the A/D converter to
convert it into digital form and then it is send to the control unit of microcontroller from where
the O/P’s are controlled by the mechanism stored in microcontroller unit.
Fig 3.1: Wireless Sensor Node Architecture
The topology of the WSNs can vary from a simple star network to an advanced multi-hop
wireless mesh network. The propagation technique between the hops of the network can be
routing or flooding.
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Fig 3.2: Sensor Node And Gateway Sensor Node
The processor is responsible for managing and coordinating various activities of the
sensor node and for processing data. The sensors measure some properties of the physical
environment. The Analog-to-Digital Converter (ADC) converts the analog data measured by the
sensors to digital format so that it can be stored and processed.
The transceiver is a radio device that can receive and transmit information. If the node is
part of a network, data can be transmitted from the source to the destination using single hop or
multiple hops communication.
The power source supplies power to the sensors and to the other components of the
sensor node. The power source may be supported by power scavenging units such as solar cells .
The processor also stores the collected data in the memory until it is forwarded to the
The processor generates control messages that direct the sensor to start or stop collecting
information about the environment and direct the transceiver to be either in the receiving mode
or transmitting mode depending upon the scenario. When the node is part of a network, the
processor also keeps information about its neighboring nodes, decides the routing path and
communicates the routing information to the other nodes.
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Fig 3.3: Block Diagram of A Sensor Node
Sensors are the very important part of any sensor network it is the primary hub of
wireless sensor networks. All wireless technology is depend upon these sensors in our general
life we use many sensors, do u know that how much sensors are working in your system or in
your mobile cell. U cannot think about a network without sensor.
A 'sensor' is a device that measures a physical quantity and converts it into a 'signal'
which can be read by an observer or by an instrument. For example, a mercury thermometer
converts the measured temperature into the expansion and contraction of a liquid which can be
read on a calibrated glass tube.
3.2 THE TREND OF SENSORS
Because of certain disadvantages of physical contact sensors, newer technology non-
contact sensors have become prevalent in industry, performing well in many applications. The
recent style of non-contact sensors shows that “Thin (g) is In”. Market trends show that form and
size are important.
Users are looking for smaller and more accurate sensors. New technologies for the
sensing chips are breaking application barriers. For the future, the trend will be to continue to
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provide smaller, more affordable sensors that have the flexibility to fit even more applications in
both industrial and commercial environments.
3.3 TYPES OF WSNs:
terrestrial WSN, underground WSN, underwater WSN, multi-media WSN, and mobile WSN.
Terrestrial WSNs :
TWSN typically consist of hundreds to thousands of inexpensive wireless sensor
nodes deployed in a given area, either in a pre-planned or in an ad-hoc manner. In pre-
planned deployment, there is grid placement, optimal placement , 2- d and 3-d
placement [3, 4] models. In ad-hoc deployment, sensor nodes can be dropped from a
plane and randomly placed into the target area.
Underground WSNs [5, 6]:
UWSN consists of number of sensor nodes buried underground or in a cave or
mine that are used to monitor underground conditions. Some additional sink nodes are
located above ground to relay information from the sensor nodes to the base station. An
underground WSN is usually more expensive than a terrestrial WSN in terms of
equipment, deployment, and maintenance.
Underwater WSNs [7, 8]:
These consist of a several sensor nodes and vehicles that are deployed
underwater. As compared to terrestrial WSNs, underwater sensor nodes are more
expensive and fewer no. of sensor nodes are deployed. Autonomous underwater vehicles
are used for exploration or gathering data from sensor nodes. Compared to a dense
deployment of sensor nodes in a TWSN, a sparse deployment of sensor nodes is placed
underwater. Typical underwater wireless communications are established through
transmission of acoustic waves.
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Multi-media WSNs :
These have been proposed to enable monitoring and tracking of events in the form
of multimedia. Multi-media WSNs consist of a several low cost sensor nodes equipped
with cameras and microphones. These sensor nodes usually interconnect with each other
over a wireless connection for data retrieval, process, correlation, and compression.
Multi-media sensor nodes are typically deployed in a pre-planned manner into the
environment to guarantee coverage. Challenges in such WSN include high bandwidth
demand, high energy consumption, quality of service (QoS) provisioning, data processing
and compressing techniques, and cross-layer design.
MWSN consist of a no. of sensor nodes that can move on their own and also
interact with the physical environment. Mobile nodes have the ability to sense, compute,
and communicate like static nodes. Mobile nodes also have the ability to reposition and
organize itself in the network. A mobile WSN can start off with some initial deployment
and nodes can then spread out to gather information. Information gathered by a mobile
node can be communicated to another when they are within range of each other. Another
key difference is of data distribution. In a static WSN, data can be distributed using fixed
routing or flooding while in a mobile WSN, dynamic routing is used. Challenges in this
type of WSN include deployment, localization, self-organization, navigation and control,
coverage, energy, maintenance, and data process.
3.4 ISSUES RELATED TO WSN
Due to the deployment of sensor nodes in an uncontrolled or harsh environment,
it is not uncommon for the sensor nodes to become faulty and unreliable .
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The events which the framework deals with are urgent which should be
recognized immediately by the operator. Therefore, the framework has to detect and
notify the events quickly as soon as possible.
A system, whose performance improves after adding hardware, proportionally to
the capacity added, is said to be a scalable system. The number of sensor nodes deployed
in the sensing area may be in the order of hundreds or thousands, or more.
In a multi-hop sensor network, 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.
One fundamental problem in wireless sensor networks is the coverage problem,
which reflects the quality of service that can be provided by a particular sensor network.
The coverage problem is defined from several points of view due to a variety of sensor
networks and a wide-range of their applications.
Geographic routing is a routing principle that relies on geographic position
information. It is mainly proposed for wireless networks and based on the idea that the
source sends a message to the geographic location of the destination instead of using the
A routing hole consists of a region in the sensor network, where either node are
not available or the available nodes cannot participate in the actual routing of the data
due to various possible reasons. The task of identifying holes is especially challenging
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since typical wireless sensor networks consist of lightweight, low-capability nodes that
are unaware of their geographic location.
Coverage problem reflects how well an area is monitored or tracked by sensors.
The coverage and connectivity problems in sensor networks have received considerable
attention in the research community in recent years. This problem can be formulated as a
decision problem, whose goal is to determine whether every point in the service area of
the sensor network is covered by at least k sensors, where k is a given parameter.
The major issues that affect the design and performance of a wireless sensor network are as
Hardware and Operating System for WSN
Wireless Radio Communication Characteristics
Medium Access Schemes
Data Aggregation and Data Dissemination
Database Centric and Querying
Programming Models for Sensor Networks
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CHARACTERISTICS & FEATURES
The key characteristic of any Wireless Sensor Network includes:
Power consumption constraints for nodes using batteries or energy harvesting
Chance to cope with node failures (resilience)
Mobility of nodes
Heterogeneity of nodes
Scalability to large scale of deployment
Capability to withstand harsh environmental conditions
Simplicity of use
Cross layer design
In spite of the diverse applications, sensor networks pose a number of unique technical
features due to the following factors:
Ad hoc deployment:
Most sensor nodes are deployed in regions which have no infrastructure at all. A
typical way of deployment in a forest would be tossing the sensor nodes from an aero
plane. In such a situation, it is up to the nodes to identify its connectivity and
In most cases, once deployed, sensor networks have no human intervention.
Hence the nodes themselves are responsible for reconfiguration in case of any changes.
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The sensor nodes are not connected to any energy source. There is only a finite
source of energy, which must be optimally used for processing and communication? An
interesting fact is that communication dominates processing in energy consumption.
Thus, in order to make optimal Use of energy, communication should be minimized as
much as possible.
It is required that a sensor network system be adaptable to changing Connectivity
(for e.g., due to addition of more nodes, failure of nodes etc.) as well as changing
Environmental stimuli. Thus, unlike traditional networks, where the focus is on
maximizing channel throughput or minimizing node deployment, the major
consideration in a sensor network is to extend the system lifetime as well as the system
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Research Challenges in Wireless Sensor Networks
A brief history on the research in SN, but more interesting may be the overview within
the technical challenges and issues is presented, from where we could cite several relevant
items: WSN working in a harsh environment; the ability with the network (leastways the
neighbors); the network control and routing; querying and tasking (should be as simple and
intuitive as it can be); plus security issues (low latency, survivable, low probability of
detecting communications, high reliability).
Security is often a broadly used term encompassing the characteristics of
authentication, integrity, privacy, non repudiation, and anti-playback. The greater the
dependency on the info supplied by the networks may be increased, the more potential
risk of secure transmission of information in the networks has increased. To the secure
transmission of numerous kinds of information over networks, several cryptographic,
steganography and other techniques are utilized that happen to be renowned. In this
section, we discuss the network security fundamentals you bet the techniques are meant
for wireless sensor networks.
The encryption-decryption techniques devised for your traditional wired networks
usually are not feasible to be employed directly for the wireless networks in particular for
wireless sensor networks. WSNs include things like tiny sensors which really suffer from
the possible lack of processing, memory and battery Applying the security mechanisms
for instance encryption could also increase delay, jitter and packet loss in wireless sensor
networks when applying encryption schemes to WSNs like, what sort of keys are
generated or disseminated. How a keys are managed, revoked, assigned to your new
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sensor put into the network or renewed for ensuring robust to protect the network
Adoption of pre-loaded keys or embedded keys could hardly be an efficient solution.
While cryptography aims at hiding necessary of a message, steganography aims at
hiding a good the message. Steganography is the art of covert communication by
embedding a note in to the multimedia data (image, sound, video, etc.). The leading
objective of steganography is to modify the carrier in a fashion that is just not perceptible
and hence, it looks the same as ordinary.
Physical Layer Secure Access:
Physical layer secure access in wireless sensor networks may very well be offered
by using frequency hopping. A dynamic mixture of the parameters like hopping set
(available frequencies for hopping), dwell time (interval per hop) and hopping pattern
(the sequence in which the frequencies in the available hopping set is used) could be
combined with a little expense of memory, processing and resources. Important points in
physical layer secure access will be the efficient design in order that the hopping
sequence is modified in less time than is required to discover it and for employing this
both sender and receiver should maintain a synchronized clock.
It is amongst the key techniques in wireless sensor network. The place estimation
method is usually classified into Target source localization and node self-localization. In
target localization, we mainly introduce the energy-based method. Then we investigate
the node self-localization methods. Considering that the widespread adoption on the
wireless sensor network, the localization methods are wide and varied in several
applications. There are some challenges using some special scenarios. Localization in
wireless sensor networks is the process of determining the geographical positions of
sensors. Only a number of the sensors (anchors) inside the networks have prior
knowledge about their geographical positions. Localization algorithms utilize location
information of anchors and estimates of distances between neighboring nodes to discover
the positions in the rest of the sensors.
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A wireless sensor node can be a popular solution when it is difficult or impossible
to perform a mains supply towards sensor node. However, because the wireless sensor
node is normally positioned in a hard to reach location, changing the battery regularly
will not be free and inconvenient. An essential take into account the introduction of a
wireless sensor node is making sure that there's always adequate energy accessible to
power the system. The facility consumption rate for sensors in the wireless sensor
network varies greatly good protocols the sensors use for communications.
Sensor networks provide capability to monitor real-world phenomena in more
detail and also at large scale by embedding wireless network of sensor nodes in the
environment. Here, deployment is anxious with establishing an operational sensor
network inside a real-world environment. On many occasions, deployment is often a
labor-intensive and cumbersome task as environmental influences trigger bugs or
degrade performance in a way that is not observed during pre-deployment testing within
a lab. The real reason for this really is that the real life features a strong influence for the
function of your sensor network by governing the output of sensors, by influencing the
existence and excellence of wireless communication links, and also by putting physical
strain on sensor nodes.
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The original motivation behind the research into WSNs was military application.
Examples of military sensor networks include large-scale acoustic ocean surveillance systems for
the detection of submarines, self-organized and randomly deployed WSNs for battlefield
surveillance and attaching micro sensors to weapons for stockpile surveillance (Pister, 2000). As
the costs for sensor nodes and communication networks have been reduced, many other potential
applications including those for civilian purposes have emerged. The following are a few
Fig 6.1: Applications of WSNs
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Environmental monitoring (Steere et al., 2000) can be used for animal tracking,
forest surveillance, flood detection, and weather forecasting. It is a natural candidate for
applying WSNs, because the variables to be monitored, e.g. temperature, are usually
distributed over a large region. One example is that researchers from the University of
Southampton have built a glacial environment monitoring system using WSNs in
Norway (Martinez et al., 2005). They collect data from sensor nodes installed within the
ice and the sub-glacial sediment without the use of wires which could disturb the
WSNs can be embedded into a hospital building to track and monitor patients and
all medical resources. Special kinds of sensors which can measure blood pressure, body
temperature and electrocardiograph (ECG) can even be knitted into clothes to provide
remote nursing for the elderly. When the sensors are worn or implanted for healthcare
purposes, they form a special kind of sensor network called a body sensor network
(BSN). BSN is a rich interdisciplinary area which revolutionizes the healthcare system
by allowing inexpensive, continuous and ambulatory health monitoring with real-time
updates of medical records via the Internet.
Sensor networks have been used for vehicle traffic monitoring and control for
some time. At many crossroads, there are either overhead or buried sensors to detect
vehicles and to control the traffic lights. Furthermore, video cameras are also frequently
used to monitor road segments with heavy traffic. However, the traditional
communication networks used to connect these sensors are costly, and thus traffic
monitoring is usually only available at a few critical points in a city (Chong & Kumar,
2003). WSNs will completely change the landscape of traffic monitoring and control by
installing cheap sensor nodes in the car, at the parking lots, along the roadside, etc.
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Street line, Inc. (Street line, Inc., n.d.) is a company which uses sensor network
technology to help drivers find unoccupied parking places and avoid traffic jams. The
solutions provided by Street line can significantly improve the city traffic management
and reduce the emission of carbon dioxide.
The New York Times Building - a Smart Building
The headquarters of the New York Times is an example of how different smart
building technologies can be combined to reduce energy consumption and to increase
user comfort. Overall, the building consumes 30% less energy than traditional office
skyscrapers. Opened in November 2007 and designed by Renzo Piano, the building has a
curtain wall which serves as a sunscreen and changes color during the day. This wall
consists of ceramic rods, “a supporting structure for the screen and an insulated window
unit” (Hart, 2008).
The building is further equipped with lighting and shading control systems based
on ICT technologies. The lighting system ensures that electrical light is only used when
required. Further day lighting measures include a garden in the centre of the ground floor
which is open to the sky as well as a large area skylight.
The electrical ballasts in the lighting system are equipped with chips that allow
each ballast to be controlled separately. The shading system tracks the position of the sun
and relies on a sensor network to automatically actuate the raising and lowering of the
The high-tech HVAC system is equipped with sensors that measure the
temperature. It is further able to rely on free air cooling, i.e. fresh air on cool mornings is
brought into the HVAC system. An automated building system monitors in parallel “the
air conditioning, water cooling, heating, fire alarm, and generation systems” (Siemens,
The system relies on a large-scale sensor network composed of different kinds of
sensors which deliver real-time information. Consequently, energy can be saved as only
as few systems are turned on as needed.
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Fig 6.2: Smart Building
While the future of WSNs is very prospective, WSNs will not be successfully
deployed if security, dependability and privacy issues are not addressed adequately.
These issues become more important because WSNs are usually used for very critical
applications. Furthermore, WSNs are very vulnerable and thus attractive to attacks
because of their limited prices and human-unattended deployment .IT provides kee
management, authentication, intrusion detection, privacy protection which makes WSN
Area monitoring is very common using WSNs. In area monitoring, the WSN is
deployed spanning a region where some phenomenon is usually to be monitored. A
military example may be the use of sensors detect enemy intrusion; A civilian
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example would be the geo-fencing of gas or oil pipelines. Area monitoring is most
There are numerous applications in monitoring environmental parameters samples
of which are given below. They share any additional challenges of harsh environments
and reduced power supply.
Polluting of the environment monitoring:
Wireless sensor networks have been deployed in lots of cities (Stockholm,
London and Brisbane) to monitor the power of dangerous gases for citizens. These can
leverage the random wireless links instead of wired installations that also make them
more mobile for testing reading sin several areas.
Forest fire detection:
A network of Sensor Nodes is usually positioned in a forest to detect every time a
fire has begun. The nodes are usually with sensors to measure temperature, humidity and
gases which are produced by fire within the trees or vegetation. The first detection is
necessary to get a successful action of the fire fighters; As a result of Wireless as Sensor
Networks, the fire brigades are able to know when a fire begins you bet it can be
A landslide detection system uses a wireless sensor network to detect the slight
movements of soil and modifications to various parameters that will occur before or
throughout a landslide. With the data gathered it may be possible to know the
appearance of landslides before it genuinely happens.
Water quality monitoring:
Water quality monitoring involves analyzing water properties in dams, rivers,
lakes & oceans, and also underground water reserves. The application of many wireless
distributed sensors enables the creation of a accurate map on the water status, and allows
the permanent deployment of monitoring stations in locations of difficult access, while
not manual data retrieval.
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Natural disaster prevention:
Wireless sensor networks can effectively act to avoid the results of disasters, like
floods. Wireless nodes have successfully been deployed in rivers where changes in the
water levels have to be monitored in real time.
a. Machine health monitoring:
Wireless sensor networks happen to be developed for machinery condition
based maintenance (CBM) as they offer significant personal savings and enable
new functionality. In wired systems, installing enough sensors can often be tied to
the price of wiring. Previously inaccessible locations, rotating machinery,
hazardous or restricted areas, and mobile assets can now be reached with wireless
b. Data logging:
Wireless sensor networks are also employed for the gathering of web data
for monitoring of environmental information; this is often as easy as the
monitoring from the temperature in a very fridge to the level of water in overflow
tanks in nuclear power plants. The statistical information will then be employed to
show how systems have been working. The main benefit of WSNs over
conventional loggers is the "live" data feed which is possible.
c. Water/Waste water monitoring:
Monitoring the high quality and level of water includes many activities
including checking the quality of underground or surface water and ensuring a
country’s water infrastructure for your benefit of both human and animal .It may
be helpful to protect the wastage of water.
d. Structural Health Monitoring:
Wireless sensor networks enables you to monitor the fitness of civil
infrastructure and related geophysical processes all around real time, and more
than very long stretches through data logging, using appropriately interfaced
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ADVANTAGES AND DISADVANTAGES
Why people love wireless sensor networks might be summarized as the following:
Network setups can be carried out without fixed infrastructure.
Suitable for the non-reachable places such as over the sea, mountains, rural
areas or deep forests.
Flexible if there is random situation when additional workstation is needed.
Implementation pricing is cheap.
It avoids plenty of wiring.
It might accommodate new devices at any time.
It's flexible to undergo physical partitions.
It can be accessed by using a centralized monitor.
The disadvantages of wireless sensor networks can be summarized as follows :
Less secure because hackers can enter the access point and obtain all the
Lower speed as compared to a wired network.
More complicated to configure compared to a wired network.
Easily troubled by surroundings (walls, microwave, large distances due to signal
Comparatively low speed of communication.
Still Costly (most importantly).
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Wireless Sensor Networks (WSNs) consist of small nodes with sensing, computation, and
wireless communications capabilities. Many routing, power management, and data dissemination
protocols have been specifically designed for WSNs where energy awareness is an essential
design issue. As wireless sensor networks are still a young research field, much activity is still
ongoing to solve many open issues. As some of the underlying hardware problems, especially
with respect to the energy supply and miniaturization, are not yet completely solved, wireless
sensor networks are having certain short comings, which are to be solved.
WSNs have been identified as one of the most prospective technologies in this century..In
concrete terms, the hardware, software and networking protocol design of this important
technology.The security and ongoing standardization of this technology. Depending on
applications, many other techniques such as localization, synchronization.
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