Wireless Sensors Network Presentation

7/27/2019 Wireless Sensors Network Presentation

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Wireless Sensors Network



What is Sensor?

A sensor is a device that

measures a physicalquantity(for example:temperature, blood

pressure, humidity, speed,etc.) and converts it into a

signal which can be read by an observer or by aninstrument.e.g

proximity,motion,temperture,pressure,IR,UV, Bar-

code Identification andtouch sensors etc.



Sensor and Actuator

• Sensors: Gatherather & transfer information.

• Actuators: transfer info, make decisions and perform actions.



Criteria to choose a Sensor

Accuracy

Environmental condition - usually has limits for temperature/ humidity

Range - Measurement limit of sensor

Calibration - Essential for most of the measuringdevices as the readings changes with time

Resolution - Smallest increment detected by thesensor

Cost

Repeatability - The reading that varies is repeatedlymeasured under the same environment



Classification of Sensors

The sensors are classified into the following criteria:

1. Primary Input quantity (Measurand)

2. Transduction principles (Using physical and

chemical effects)3. Material and Technology

4. Property

5. ApplicationTransduction principle is the fundamental criteriawhich are followed for an efficient approach



What are Wireless Sensors?

• Wireless sensors are standard measurement

tools equipped with transmitters to convert

signals from process control instruments into a

radio transmission.

• The radio signal is interpreted by a receiver

which then converts the wireless signal to a

specific, desired output, such as an analogcurrent or data analysis via computer software.



What are the primary benefits to

using wireless sensors?

1. Safety:Wireless instruments can be used in locations that are

difficult to access due to extreme conditions such as high

temperature, pH, pressure, etc.

2. Convenience:Wireless sensors can be used to form a

web/network that would allow an engineer to monitor a

number of different locations from one station. This provides

a centralized control of a factory.

3. Reduce Costs:Wireless process control can reduce the cost

of monitoring and running a factory by eliminating the needfor extension wire, conduit, and other costly accessories.



Selecting a Wireless Sensor

1. Type of Measurement: It is important to understand what is being

measured.

2. Accuracy and Response Time: How accurate does the measurement

need to be, and how quickly should the measurement be updated?

3. Range: The range of wireless sensors varies widely. Some are designedfor short-range, indoor applications of a few hundred feet, while other

sensors can transmit data to a receiver located miles away.

4. Frequency: The frequency of radio transmission is also important

to consider. Laws vary by country and region as to which parts of

the wireless spectrum are available for use without specificlicenses



Types of Wireless Sensors

1. Transmitters use scientific sensors such as thermocouples, pressuretransducers, flow meters, etc. to measure a specific property in a process, andthen transmit the data via radio signals to a receiver.

2. Receivers receive and interpret the wireless data. The receiver 'reads' a radiosignal and converts it into the desired output such as contact closure, analogoutput, or digital display; some receivers can even export the data to

advanced software.3. Controllers function similar to a receiver in the sense that they receive and

analyze data from wireless transmitters.

4. Data Loggers form a special type of wireless measurement network as theycan remotely monitor temperature anywhere and then transmit the data back to an engineer once the unit is brought to a receiver.

5. Transceivers contain a transmitter and receiver in a single unit. Theability to rebroadcast signals makes wireless transceivers able to extendthe range of your wireless measurement network.



Network(WSN)

Definition:Wireless sensor network (WSN) refers to a group of spatiallydispersed and dedicated autonomoussensors for monitoring and recordingthe physical conditions of theenvironment and organizing thecollected data at a central location.

A sensor network is composed of alarge number of sensor nodes, which

are densely deployed either inside the phenomenon or very close to it.

WSNs measure environmentalconditions like temperature, sound,

pollution levels, humidity, windspeed and direction, pressure, etc.

The WSN is built of "nodes" – from

a few to several hundreds or eventhousands, where each node isconnected to one (or sometimesseveral) sensors.



Wireless Sensor Node

• A sensor node, also known as amote is a node in a wireless

sensor network that is capable of performing some processing,gathering sensory information andcommunicating with other connected nodes in the network. Amote is a node but a node cannot

always be a mote.• The main components of a sensor

node are:

1. Power Supply

2. Sensing Unit

3. Processing Unit4. Communication Unit

5. Software



WSN Architecture

1. Processing Unit:It is responsible for collecting data from various sources then

processes it and stores it. The central process unit of sensor node determines energy

consumption and computational capabilities of a node.

a. Microcontroller-It is general purpose processor used for processing. It is not only

consists of memory and processor but also non-volatile memory and interfaces. It helps to

reduce the requirement of wiring, extra hardware, circuit board space and energy. For

saving of power, microcontroller should have three states-active, sleeps, idle.b. Timer/Clock- Timer is a special type of clock. As it is asynchronous technology but for

sequencing of sequence, it need timer.

c. Operating System- WSN uses less complex operating system as compared to general

purpose operating system in the sense that it uses few thousands of lines for coding the

system whereas general-purpose consist of millions of lines of codes.

d. Memory-Here, we use RAM as an internal memory for storing information in

microcontroller. We can also use flash memory which is used for storing program code.

However, Size of memory can affect consumption of power and cost. Thus, selecting the

appropriate size of memory is important and can be selected according to application.



WSN Architecture1. Power supply- are responsible for providing energy to the sensor node for

monitoring the environment at low-cost and time. It takes energy from power generator and pass to other component of node. Life of sensor node depends upon battery so battery is the important component that must be distribute properly.

2. Communication or Transceiver Unit- A transceiver is a unit in which transmitter as well as receiver is sharing same circuitry on single board. It receives commandfrom processing unit and passes it to the other node of the network.

3. Software- It provides four services such as i)sensor manager which provide accessto sensors and manage the delivery of sensor data, ii)storage is responsible for providing the persistent storage for data streams, iii)query manager performs query processing and manages active queries, iv) integrity services is used for accesscontrol.

4. Sensing Unit- It has two parts:

a. A/D converter- It is used for converting the analog signal into digital signal. Ittakes an analog signal from sensor and converts it into digital signal and relay tomicrocontroller for further processing.

b. Sensors- is device that sense physical phenomenon such as pressure, motion, speedetc and transform it into analog signal and the same signal are processed by analogto digital converter. It could be active or passive.



Sensor networks VS ad hoc networks:

• The number of nodes in a sensor network can be

several orders of magnitude higher than the nodes inan ad hoc network.

• Sensor nodes are densely deployed.

• Sensor nodes are limited in power, computational

capacities and memory.• Sensor nodes are prone to failures.

• The topology of a sensor network changes frequently.

• Sensor nodes mainly use broadcast, most ad hoc

networks are based on p2p.• Sensor nodes may not have global ID.



Why WSN

Different communication model

Not regular “end-to-end” communication in that itis the phenomenon not nodes that matters

Resource constrainedSimplicity of protocol and energy conservation

Trade-off between computation and

communicationSending 1 bit 100m by radio = executing 3000

instructions



Common Wireless Sensor

Network Architecture

• In a common WSNarchitecture, the measurementnodes are deployed to acquiremeasurements such astemperature, voltage, or evendissolved oxygen.

• The nodes are part of a wirelessnetwork administered by thegateway, which governsnetwork aspects such as clientauthentication and datasecurity.

• The gateway collects themeasurement data from eachnode and sends it over a wiredconnection, typically Ethernet,to a host controller.



Tele-Medical Care or m-Health Care

• Tele-Medical is a trend of combining telecommunication technology andmedicine to create telemedicine and Tele-healthcare. In other words we cancall it as a cross-fertilization of medicine and telecommunication.

• Telemedicine applications further can be classified into two categories.The first one is called “store and forward” (for Tele-radiology, where x-rays, CT scans, and MRIs reports transmission) which is being used for

transferring digital images from one location to another. This type of technology is utilized for non-emergent situations, when there’s time for anappointment (diagnosis or consultation) to be made, usually within 24 to 48hours.

• The second most widely-used technology in telemedicine is two-way,interactive television (IATV). It is mainly used in coordinate consultations

when patients, along with their healthcare provider (a doctor or a nurse practitioner) and a telemedicine coordinator (or a combination of the three),gather at one site (the originating site), and a specialist is at another site (thereferral site) which is usually at large, metropolitan medical centre.



Treatment Procedure



Treatment Procedure

The Tele-Health Care procedure is completed in three simple steps:

1. The advanced wireless sensors called peripheral sensors i.eHandheld Ultra-sound(new but more sensitive stethoscope) andsmart band-aids etc which can be put on the shoes, chest, wristforehead etc sense the required information and send this body

area network to a gateway using a wireless link.2. The Gateway is a Smart phone/iPhone devices or a dedicated

gateway which then transmit this signal to Web or a radio tower.

3. The tower or Web terminal processes it to some medical expert or to another smart phone in a distant location.

This technology deals with the diseases like Alzheimer’s(5 millionaffected), Asthma(23 million), Breast Cancer(3 million), Depression(21million), Diabetes(24 million), Heart Failure(5M), Hypertension(74M),Obesity(80M) and sleep disorders(40M) etc.

Wireless Sensors Network Presentation

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