Smart Dust Final Year(Technical Topic)

8/2/2019 Smart Dust Final Year(Technical Topic)

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SMART DUSTPRESENTED BY

LAVI AGARWAL

0715331051


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What is Smart Dust?

A tiny dust size device with extra-ordinarycapabilities.

Often called micro electro-mechanical sensors

Combines sensing, computing, wirelesscommunication capabilities and autonomouspower supply within volume of only few

millimeters.Useful in monitoring real world phenomenonwithout disturbing the original process.


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Cont

so small and light in weight that theycan remain suspended in theenvironment like an ordinary dustparticle.

the air currents can also move them inthe direction of flow.

It is very hard to detect the presence ofthe Smart Dust and it is even harder toget rid of them once deployed.


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Smart Dust Mote


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Architecture

A single Smart Dust mote has:

a semiconductor laser diode and MEMS beam

steering mirror for active optical transmission

a MEMS corner cube retro-reflector for passive

optical transmission

an optical receiver

a signal processing and control circuitry

a power source based on thick-film batteries and

solar cells.


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Components of Smart Dust


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Corner Cube Retro-reflector(CCR)

Comprises of three mutuallyperpendicular mirrors of gold-coated

poly-silicon.Has the property that any incident rayof light is reflected back to the source

provided that it is incident within acertain range of angles centered aboutthe cubes body diagonal.


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CCR cont

The micro-fabricated CCR includes anelectrostatic actuator that can deflect

one of the mirrors at kilohertz rates.Thus the external light source can betransmitted back in the form of

modulated signal at kilobits per second.


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Note (CCR cont)

CCR-based passive optical links require anuninterrupted line-of-sight path.

CCR can transmit to the BTS only when the

CCR body diagonal happens to point directlytoward the BTS, within a few tens of degrees.

A passive transmitter can be made moreomni-directional by employing several CCRsoriented in different directions, at theexpense of increased dust mote size.


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Challenges

It is difficult to fit all these devices in asmall Smart Dust both size wise and

Energy wise.With devices so small, batteries presenta massive addition of weight.


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Free Space Optical Network


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Communication Technologies

Radio Frequency Transmission

Optical transmission technique

a) Passive Laser based Communicationb) Active Laser based Communication

c) Fiber Optic Communication


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Radio Frequency Transmission

Based on the generation, propagation anddetection of electromagnetic waves with afrequency range from tens of kHz to

hundreds of GHz.Multiplexing techniques: time, frequency orcode-division multiplexing.

Their use leads to modulation, bandpassfiltering, demodulation circuitry, andadditional circuitry, all of which needs to beconsidered, based on power consumption.


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Problems with RF comm..

Large size of antenna.

RF communication can only be achieved

by using time, frequency or codedivision.

TDMA, FDMA, and CDMA have their

own complications.


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Passive Laser based comm..

Downlink communication (BST to dust)- thebase station points a modulated laser beamat a node.Dust uses a simple optical receiverto decode the incoming message

Uplink communication (dust to BST)- thebase station points an un-modulated laser

beam at a node, which in turn modulates andreflects back the beam to the BST


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Advantages

Optical transceivers require only simplebaseband analog and digital circuitry; nomodulators, active bandpass filters ordemodulators are needed.

The short wavelength of visible or near-infrared light (of the order of 1 micron)

makes it possible for a millimeter-scale deviceto emit a narrow beam (i.e. high antennagain can be achieved).


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Advantages cont

A base-station transceiver (BTS) equippedwith a compact imaging receiver can decodethe simultaneous transmissions from a large

number of dust motes at different locationswithin the receiver field of view, which is aform of space-division multiplexing.

The CCR makes make it possible for dust

motes to use passive optical transmissiontechniques, i.e., to transmit modulated opticalsignals without supplying any optical power.


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Limitations

Is a single-hop network topology,where dust nodes cannot directly

communicate with each other, but onlywith a base station.

Communication may suffer from

variable delays if the laser beam is notalready pointing at a node that issubject to communication with the BST.


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Active Laser Based comm..

Has a semiconductor laser, a collimatinglens and a beam-steering micro-mirror.

Uses an active-steered laser-diodebased transmitter to send a collimatedlaser beam to a base station .

Suitable for peer-to-peer comm..,provided there exist a line of sight pathbetween the motes.


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Advantages

One can form multi-hop networks usingactive laser based comm..

Burst-mode communication providesthe most energy-efficient way toschedule the multi-hop network.

The active laser-diode transmitteroperates at up to several tens ofmegabits per second for a fewmilliseconds


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Disadvantages

Relatively high power consumption .

Thus can be used only for a short

duration burst-mode communication.Components like active beam-steeringmechanism makes the design of the

dust mote more complicated.


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Fiber Optic comm..

Employs semiconductor laser, fibercable and diode receiver to generate,transfer and detect the optical signal.

Similar to passive optical comm..Relatively small size of the opticaltransceiver is employed with low-power

operation.CCR employed on each Dust mote tomodulate uplink data to base station.


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Fiber Optic comm. setup


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Advantages

Does not require unbroken line-of-sight andthe link directionality.

Each dust mote does not need to employmore than one CCR.

Comm.. between dust motes and a basestation can be guaranteed.

It has a longer range of communication linkthan that of a free space passive opticalcomm..


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Limitations

Optical fiber cables restrict the mobilityof dust mote.

Since a base station should employseveral optical components for fiberconnection to each dust mote, it may

complicate base station design.


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Applications

Environmental protection (identification andmonitoring of pollution).

Habitat monitoring (observing the behavior ofthe animals in there natural habitat).

Military application (monitoring activities ininaccessible areas, accompany soldiers andalert them to any poisons or dangerousbiological substances in the air).

Indoor/Outdoor Environmental Monitoring.


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Applications cont

Security and Tracking

Health and Wellness Monitoring (enter

human bodies and check forphysiological problems).

Factory and Process Automation.

Seismic and Structural Monitoring.Monitor traffic and redirecting it.


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Conclusion

There are many ongoing researches on

Smart Dust, the main purpose of these

researches is to make Smart Dust mote assmall as possible and to make it available at

as low price as possible. Soon we will see

Smart Dust being used in varied applicationfrom all spans of life.


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THANK YOU!

Smart Dust Final Year(Technical Topic)

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