58119 13238 IEEE Paper Format

8/2/2019 58119 13238 IEEE Paper Format

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SMART DUST 2010

1. INTRODUCTION

As the research community searches for the

processing platform beyond the personal computer,

networks of wireless sensors have become quite

interesting as a new environment in which to seek

research challenges. These have been enabled by the

rapid convergence of three key technologies: digital

circuitry, wireless communications, and

MicroElectroMechanicalSystems (MEMS).

In each area, advances in hardware technology

and engineering design have led to reductions in

size, power consumption, and cost. This has enabled

remarkably compact, autonomous nodes, each

containing one or more sensors, computation and

communication capabilities, and a power supply.

BerkeleysSmart Dust

project, led by ProfessorsPister and Kahn, explores the limits on size and

power consumption in autonomous sensor nodes.

Size reduction is paramount, to make the nodes as

inexpensive and easy-to deploy as possible. These

millimeter-scale nodes are called Smart Dust.

Smart dust devices are tiny wireless sensors that can

detect light and vibrations in its environment. They

also go by the name of motes. These motes could

eventually be the size of a grain of sand, though each

would contain sensors, computing circuits, bi-

directional communication technology and a power

supply as well. Many prototypes that have been

developed in the past were about the size of a small

matchbook and it was in 2001 that Kris Pister was

able to harness the latest technology to develop a

prototype smaller than the nib of a ballpoint pen

(fig.1). Even though this would seem very small to

the human eye, the ideal size would be at least a 100

times smaller than this. It is certainly within the

realm of possibility that future prototypes of Smart

Dust could be small enough to remain suspended in

air, buoyed by air currents, sensing and

communicating for hours or days on end.

These kinds of networking nodes must consume

extremely low power,communicate at bit rates

measured kilobits per second, and potentially need to

operate inhigh volumetric densities. Theserequirements dictate the need for novel ad hoc

routing and media access solutions. Smart dust will

enable an unusual range of applications, from

sensor- rich smart spaces to self-identification and

history racking for virtually any kind of physical

object.

1 Dept of IS&E,VVIET


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FIG.1 PROTOTYPE OF SMART DUST RELEASED

IN 2001

2. History

Smart dust was conceived in 1998 by Dr. Kris

Pisterof the UC Berkeley (Hsu, Kahn, and Pister

1998; Eisenberg 1999). He set out to build a device

with a sensor, communication device, and small

computer integrated into a single package.

The Defense Advanced Research Projects

Agency (DARPA) funded the project, setting as a

goal the demonstrationthat a complete

sensor/communication system can be integrated into

a cubic millimeter package .(By comparison, a

grain of rice has a volume of about 5 cubic

millimeters.)

In the early stages of the project, the team gained

experience by building relatively large motes using

components available off the shelf . One such

mote, named RF Mote,has sensors for

temperature, humidity, barometric pressure, light

intensity, tilt and vibration,and magnetic field and

it is capable of communicating distances of about 60

feet using radio frequency (RF) communication.

If the mote operated continuously, its battery

would last up to one week.One of the issues that the

UC Berkeley team faced in building smaller motes

involved powering the device. Small batteries help

minimize the size of the resulting mote, but they

contain less energy than traditional, larger batteries

and thus, they have shorter life spans (Yang 2003).

However, long battery life is critical to applications

where it would be costly, inconvenient, or impossible

to retrieve a smart dust mote in order to

replace its batteries. This would be true, for example,

with temperature and humidity-monitoring motes

placed inside the walls of a building during its

construction . Faced with the trade-off between

miniaturization and long battery life, early smart dustdevelopers leaned toward miniaturization. The Smart

Dust project Web site states that [t]heprimary

constraint in the design of Smart Dust motes is

volume, which puts a severe constrainton energy

since we do not have much room for batteries or

large solar cells(Pister 2001).

However, the team applied tactics to conserve the

available energy to prolong battery life. One

approach, taken by Dr. David Culler, was to

designsoftware that enabled the motes to sleep

most of the time yet wake up regularly to take

readings and communicate. This allows for energy

conservation during the sleep period.The UC

Berkeley team equipped some of their early motes

with optical communicationsystems in order to

reduce power consumption and allow for a smaller

device (Warneke et al. 2001). With this scheme, a

mote designated as activewas equipped with a

transmitting

device similar to what is found in the laser pointers



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used by presenters in business presentations (ibid, p.

48). Another energy-saving approach the researchers

explored was passive transmission (Hsu, Kahn, and

Pister 1998). A mote with a passive communication

system does not have anonboard light source but

instead it uses a series of mirrors controlled by a

smallelectrical charge (Warneke et al. 2001). When a

laser is pointed toward the mote, it can rapidly adjust

the position of its mirrors to send messages encoded

in pulses of light; the message could then be read by

a special optical receiver. This passivecommunication system proved effective in reducing

energy consumption, but it has limitations because

passive motes in a network cannot directly

communicate with one another and instead have

to rely on a central station equipped with a light

source to send and receive data from other motes

A common mote communication scheme utilizes

radio frequency (RF) signals to communicate over

relatively short distances.This allows designers to

minimizemote size and power consumption (Webb

2003). When communicating, the devices

compensate for this by passing each message to a

neighboring mote which, in turn, passes the Dust

Networks message on to another nearby mote, and so

on, until the message reaches the destination

thecentral monitoring station associated with the

group of motes (ibid). . As implemented, the

networks formed by motes are fairly robust; that is, a

network ofmotes continues to perform even if some

of its communication paths fail to operate. And once

a mote is placed in an existing network, it adapts to

blend in with the other nodes to form a larger

network; and when a mote fails, the other devices in

the network take over its load . The operation of

motes in a mesh network has been described as

analogous to the way a soccer team passes the ball

until it reaches its destination During the course of

the Smart Dust project, Professor David Culler and a

team of researchers at UC Berkeley created the

TinyOS operating system (Yang 2003). Once

installed on a mote,this software is responsible for operating the device,

managing its power consumption, and

facilitating communication with other motes (ibid).

The software is open-source and available

athttp://www.tinyos.net(Webb 2004).

The Smart Dust project resulted in laboratory and

field demonstrations of a few generations of

motes with names like Clever Dust, Deputy Dust,

Daft Dust, and Flashy Dust (Pister 2001).

More importantly, it spurred the interest of numerousother academic and corporate researchers

The Generations of Smart Dust Motes

GolemDust

solar powered mote with bi-directional

http://www-bsac.eecs.berkeley.edu/~warneke/SmartDust/http://www.nanotech-now.com/images/golem-dust-penny-large.jpghttp://www-bsac.eecs.berkeley.edu/~warneke/SmartDust/


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communications and sensing (acceleration andambient light) 11.7 mm3 total circumscribedvolume ~4.8 mm3 total displaced volume

DaftDust

63 mm3 bi-directional communication mote

Flashy Dust

138 mm3 uni-directional communication andsensing (ambient light) mote

2.1 Smart Dust Today

Tiny, ubiquitous, low-cost, smart dust motes

have not yet been realized, however,

somereasonably small motes are commercially

available. One of these, the MICA2DOT, is 6

available from Crossbow Technology, Inc.

The unit becomes a mote once a small

sensorboard, coin battery, and antenna are

added to the product (Crossbow 2004b). In

addition, Crossbow sells larger motes (about

the size of a deck of cards), which are

compatible with more types of sensors. Other

commercially available motes are sold by Dust

Networks. Thiscompany offers motes which

areabout the size of a matchbook,operate on

two AA batteries and have a 5-year battery life

(Metz 2004). Many of the sensors available for

smart dust motes are micro-electromechanical

systems

2.1 Smart Dust Today

Tiny, ubiquitous, low-cost, smart dust motes

have not yet been realized, however, some

reasonably small motes are commercially

available. One of these, the MICA2DOT, is 6

available from Crossbow Technology, Inc.

The unit becomes a mote once a small

sensorboard, coin battery, and antenna are

added to the product.

The MICA2DOT mote, typically powered by a circular

http://www.nanotech-now.com/images/flashy-dust-sem2-large.gifhttp://www.nanotech-now.com/images/daft-dust-semsys-150-large.gif


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button battery, is not much bigger than a quarter.

2. SMART DUST COMPONENTS

A Smart Dust mote is illustrated in Figure 2.

Integrated into a single package are

MEMS sensors, a semiconductor laser diode and

MEMS beam-steering mirror for active

optical transmission, a MEMS corner-cube

retroreflector for passive optical transmission,

an optical receiver, signal-processing and control

circuitry, and a power source based on

thick-film batteries and solar cells. This remarkable

package has the ability to sense and

communicate, and is self-powered. A major

challenge is to incorporate all these functions

while maintaining very low power consumption,

thereby maximizing operating life given

the limited volume available for energy storage.

Within the design goal of a cubic

millimeter volume, using the best available battery

technology, the total stored energy is on

the order of 1 Joule. If this energy is consumed

continuously over a day, the dust mote

power consumption cannot exceed roughly 10

microwatts. The functionality envisioned for

Smart Dust can be achieved only if the total power

consumption of a dust mote is limited o

microwatts levels, and if careful power management

strategies re utilized (i.e., the various

parts of the dust mote are powered on only when

necessary). To enable dust motes to

function over the span of days, solar cells could be

employed to scavenge as much energy

as possible when the sun shines (roughly 1 Joule per

day) or when room lights are turned

on (about 1 millijoule per day).

Techniques for performing sensing and processing at

low power are reasonably wellunderstood. Developing communication architecture

for ultra-low-power represents a more

critical challenge. The primary candidate

communication technologies are based on radio

frequency (RF) or optical transmission techniques.

Each technique has its advantages and

disadvantages. RF presents a problem because dust

motes offer very limited space for

antennas, thereby demanding extremely short-

wavelength (i.e., high frequency)

transmission. Communication in this regime is not

currently compatible with low power

operation. Furthermore, radio transceivers are

relatively complex circuits, making it

difficult to reduce their power consumption to the

required microwatt levels. They require

modulation, band pass filtering and demodulation

circuitry, and additional circuitry isrequired if the

transmissions of a large number of dust motes are to



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be multiplexed usingtime-, frequency- or code-

division multiple access.

FIG. 2 CONCEPTUAL DIAGRAM OF

OPTICAL MOTE

An attractive alternative is to employ free-space

optical transmission. Kahn and Pisters

studies have shown that when a line-of-sight path is

available, well-designed freespace

optical links require significantly lower energy per

bit than their RF counterparts. There are

several reasons for the power advantage of optical

links. Optical transceivers require only

simple baseband analog and digital circuitry; no

modulators, active bandpass filters or

demodulators are needed. The short wavelength of

visible or near-infrared light (of the

order of 1 micron) makes it possible for a millimeter-

scale device to emit a narrow beam(i.e., high antenna gain can be achieved). As another

consequence of this short wavelength,

a base-station transceiver (BTS) equipped with a

compact imaging receiver can decode

thesimultaneous transmissions from a large number

of dust motes at different locations within

the receiver field of view, which is a form of space-

division multiplexing. Successful

decoding of these simultaneous transmissions

requires that dust motes not block one

anothers line of sight to the BTS. Such blockage is

unlikely, in view of the dust motes

small size. A second requirement for decoding of

simultaneous transmission is that theimages of

different dust motes be formed on different pixels inthe BTS imaging receiver.

3. COMMUNICATION AMONG

MOTES

Smart Dusts full potential can only be attained

when the sensor nodes communicate with one

another or with a central base station. Wireless

communication facilitates simultaneous data

collection from thousands of sensors. There are

several options for communicating to and from a

cubic-millimeter computer. Radio frequency and

optical communications each have their strengthsand weaknesses.

Radio-frequency communication is well

understood, but currently requires minimum power

levels in the multiple milliwatt range due to analog

mixers, filters, and oscillators. If whisker-thin



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antennas of centimeter length can be accepted as a

part of a dust mote, then reasonably efficient

antennas can be made for radio-frequency

communication.

While the smallest complete radios are still on

the order of a few hundred cubic millimeters, there is

active work in academia and industry to produce

cubic-millimeter radios. Semiconductor lasers and

diode receivers are intrinsically small, and the

corresponding transmission and detection circuitry

for on/off keyed optical communication is moreamenable to low-power operation than most radio

schema. Perhaps most important, optical power can

be collimated in tight beams even from small

apertures. Diffraction

enforces a fundamental limit on the divergence of a

beam, whether it comes from an antenna or a lens.

Laser pointers are cheap examples of milliradian

collimation from a millimeter aperture.

Collimated optical communication has two major

drawbacks. Line of sight is required for all but the

shortest distances and narrow beams imply the

accurate pointing. Of these, the pointing accuracy

can be solved by MEMS technology and clever

algorithms, but an optical transmitter under a leaf or

in a shirt pocket is of little use to

anyone. Presently optical communication is the more

opted form of communication in

some depth due to the potential for extreme low-

power communication. We discuss it in

detail here.

3.1 OPTICAL COMMUNICATION

Two approaches to optical communications have

been explored to date: passive

reflective systems and active steered laser systems.

In a passive communication system, the

dust mote does not require an onboard light source.

Instead, a special configuration of

mirrors can either reflect or not reflect light to a

remote source.

3.1.1 PASSIVE REFLECTIVE SYSTEMS

In its simplest passive configuration, the passive

reflective device consists of three

mutually orthogonal mirrors. Light enters the CCR,

bounces off each of the three mirrors,

and is reflected back parallel to the direction it

entered. In the MEMS version, the device



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has one mirror mounted on a spring at an angle

slightly askew from perpendicularity to the

other mirrors. In this position, because the light

entering the CCR does not return along the

same entry path, little light returns to the sourcea

digital 0. Applying voltage between

this mirror and an electrode beneath it causes the

mirror to shift to a position perpendicular

to other mirrors, thus causing the light entering the

CCR to return to its sourcea digital 1.

The mirrors low mass allows the CCR to switchbetween these two states up to a thousand

times per second, using less than a nanojoule per 0_1

transition. A 1_0 transition, on the

other hand, is practically free because dumping the

charge stored on the electrode to the

ground requires almost no energy.

Figure 3 illustrates a free-space optical network

utilizing the CCR based passive

uplink. The BTS contains a laser whose beam

illuminates an area containing dust motes.

This beam can be modulated with downlink data,

including commands to wake up and

query the dust motes. When the illuminating beam is

not modulated, the dust motes can use

their CCRs to transmit uplink data back to the base

station. A highframe- rate CCD video

camera at the BTS sees these CCR signals as

lights blinking on and off. It decodes these

blinking images to yield the uplink data. Kahn and

Pisters analysis show that this uplink

scheme achieves several kilobits per second over

hundreds of meters in full sunlight, at

night, in clear, still air, the range should extend to

several kilometers. Because the camera

uses an imaging process separate the simultaneous

transmissions from dust motes different

locations, we say that it usesspace-division

multiplexing

The ability for a video camera to resolve these

transmissions is a consequence of

the short wavelength visible or near infrared light.This does not require any coordination

among the dust motes, and thus, it does not

complicate their design.

The latest Smart Dust device is a 63-mm

autonomous bi-directional

communication mote that receives an optical signal,

generates a pseudorandom sequence

based on this signal to emulate sensor data, and then

optically transmits the result. The

system contains a micromachined corner-cube

reflector, a 0.078-mm3 CMOS chip that

draws 17 microwatts, and a hearing aid battery. In

addition to a battery-based operation, we

have also powered the device using a 2-mm solar

cell. This mote demonstrates Smart

Dusts essential concepts, such as optical data

transmission, data processing, energy

management, miniaturization, and system

integration. A passive communication system



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suffers several limitations. Unable to communicate

with each other, motes rely on a central

station equipped with a light source to send and

receive data from other motes. If a given

mote does have a clear line of sight to the central

station, that mote will be isolated from

the network. Also, because the CCR reflects only a

small fraction of the light emitted from

the base station, this systems range cannot easily

extend beyond one kilometer. To

circumvent these limitations, dust motes must beactive and have their own onboard light source.

3.1.2 ACTIVE-STEERED LASER SYSTEMS

For mote-to-mote communication, an active-steered

laser communication system

uses an onboard light source to send a tightly

collimated light beam toward an intended

receiver. Steered laser communication has the

advantage of high power density; for

example, a 1-milliwatt laser radiating into 1

milliradian (3.4 arc seconds) has a density of

approximately 318 kilowatts per steradian (there are

4 _ steradians in a sphere), as opposed

to a 100-watt light bulb that radiates 8 watts per

steradian isotropic ally. A Smart Dust

motes emitted beam would have a divergence of

approximately 1 milliradian, permitting

communication over enormous distances using

milliwatts of power.

Forming ad hoc multihop networks is the most

exciting application of mote-to-mote

communication. Multihop networks present

significant challenges to current network

algorithmsrouting software must not only

optimize each packets latency but also

consider both the transmitters and receivers energy

reserves. Each mote must carefully

weigh the needs to sense, compute, communicate,

and evaluate its energy reserve status

before allocating precious nanojoules of energy to

turn on its transmitter or receiver.

Because these motes spend most of their timesleeping, with their receivers turned off,

scheduling a common awake time across the network

is difficult. If motes dont wake up in

a synchronized manner, a highly dynamic network

topology and large packet latency result.

Using burst mode communication, in which the laser

operates at up to several tens of

megabits per second for a few milliseconds, provides

the most energy-efficient way to

schedule this network. This procedure minimizes the

motes duty cycle and better utilizes

its energy reserves. The steered agile laser

transmitter consists of a semiconductor diode

laser coupled with a collimating lens and MEMS

beam-steering optics based on a two

degree-of-freedom silicon micromirror. This system

integrates all optical components into

an active 8-mm volume.

Many Smart Dust applications rely on direct optical

communication from an entire



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field of dust motes to one or more base stations.

These base stations must therefore be able

to receive a volume of simultaneous optical

transmissions. Further, communication must be

possible outdoors in bright sunlight which has an

intensity of approximately 1 kilowatt per

square meter, although the dust motes each transmit

information with a few milliwatts of

power. Using a narrow-band optical filter to

eliminate all sunlight except the portion near

the light frequency used for communication canpartially solve this second problem, but the

ambient optical power often remains much stronger

than the received signal power.

As with the transmitter, the short wavelength of

optical transmissions compared

with radio frequency overcomes both challenges.

Light from a large field of view field can

be focused into an image, as in our eyes or in a

camera. Imaging receivers utilize this to

analyze different portions of the image separately to

process simultaneous transmissions

from different angles. This method of distinguishing

transmissions based on their originating location is

referred to as space division multiple access.

Imaging receivers also offer the advantage of

dramatically decreasing the ratio of

ambient optical power to received signal power.

Ideally, the imaging receiver will focus all

of the received power from a single transmission

onto a single photodetector. If the receiver

has an n* n array of pixels, then the ambient light

that each pixel receives is reduced by a

factorn2 compared with a non-imaging receiver.

Typically, using a value fornbetween 8

and 32 makes the ambient light power negligible

compared with the electronic noise in the

analog electronics.



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COST AND AVILABILITY

The price for the motes from crossbow is about

$150 each,but for volume purchases,the price per unit

pulmates to as low as $40 The CEO of Crossbow

expects prices to drop to about $10 or less per unit.

One factor to consider when estimating the costs of

smart dust networks is ease of installation. One factor

to consider when estimating the costs of smart dust

networks is ease of installation.

Battery operated motes do not require the

installation of additional electrical wiring and their

installation simply requires a screwdriver (Dragoon

2005). In comparison to traditional wired sensors, a

smart dust mote requires no wiring and this results in

both lower labor and materials costs.Clearly, early

adopters have several commercial smart dust

products available to them in the price range of a few

hundred dollars. Late adopters can expect lower

prices as the price per mote falls. This is supported

by an Intel report excerpt. Researchers at Intel

expect that, with re-engineering, Moore's Law and

volume production, motes could drop in price to less

than $5 each over the next several years

The Intel report utilizes Moores Law which

postulates thatthe number of transistors on a chip

roughly doubles every two years, resulting in more

features, increased performance anddecreased cost

per transistor Based on this law, the assumption ofa $5 mote in the year 2010, and of the price halving

every 18 months, the price of a smart dust mote

should reach about 65 cents in 2015 and 5 cents

in2020. This is depicted in figure 1 Another

indicator of future prices is the aspirin-sized Spec

mote. Dr Jason Hill of JLH Labs estimates that when

produced in large quantities, Spec and its associated

components can be produced for a total of about 62

cents per mote (Hill 2005). Once commercially

available, Spec

is well positioned to appeal to later adopters with its

low price and small size.



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2 Early Applications

In a demonstration, smart dust was used to detect

vehicles traveling through an isolated desert

area in Palm Springs, California. The experiment,

conducted with the U.S. Marine Corps,

began when an unmanned airborne vehicle (UAV)

flew over the area, dropped 8 motes (which

were wrapped in protective foam) and then departed

(Hill 2003). After deployment, the motes

organized themselves into a network and then began

to lookout for moving vehicles

; when a

5

vehicle was detected, the mote recorded trackinginformation about the event. Eventually, the

UAV plane flew over the scene and retrieved each

nodes tracking data and then, finally,

returned to its home based to deliver the data it

collected. The experimenters successfully

downloaded the vehicle tracking information from

the plane for display on a personal

computer. In doing so, they showed how smart dust

can be used by military and law

enforcement personnel to unobtrusively monitor

movement within a region.

Scientists at the University of California at San Diego

approach smart dust from a

biotechnology perspective to produce motes from

chemical compounds rather than electrical

circuitry (Sailor, Bhatia, Cunin 2002). While not yet

commercially available, their motes have

proved useful in laboratory environments (Link and

Sailor 2003). One experiment

demonstrated the use of smart dust to detect the



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presence of hydrocarbon vapors from

approximately 65 feet away (Schmedake, T. A. et al.

2002). In thisstandoff detection,

the

researchers placed

porous silicon smart dust particles

in a gas dosing chamber and

monitored the experiment from a distance (ibid, p.

1270). Using a laser to illuminate the smart

dust and a telescope outfitted with measurement

equipment, the team detected the hydrocarbonvapors based on the changes in the light reflected

from the smart dust after it had chemically

reacted with the hydrocarbon vapors. While the

experiment was limited to hydrocarbon

vapors, the researchers predict that

with appropriate chemical modification,

the smart dust

sensors used

can specifically detect biomolecules, explosives,

(and) chemical warfare agents

The various applications that Smart Dust can be put

are endless as can be seen from the

various scenarios listed below. Smart Dust can be

implemented in practically any field

because of its ability to collect information

The Defense Advanced Research Projects Agency

(DARPA) was among the

original patrons of the mote idea. One of the initial

mote ideas implemented for DARPA

allows motes to sense battlefield conditions. For

example, imagine that a commander wants

to be able to detect truck movement in a remote area.

An airplane flies over the area and

scatters thousands of motes, each one equipped with

a magnetometer, a vibration sensor and a GPS

reciever. The battery-operated motes are dropped at

a density of one every 100

feet (30 meters) or so. Each mote wakes up, senses

its position and then sends out a radio

signal to find its neighbors.All of the motes in the area create a giant,

amorphous network that can collect data.

Data funnels through the network and arrives at a

collection node, which has a powerful

radio able to transmit a signal many miles. When an

enemy truck drives through the area,

the motes that detect it transmit their location and

their sensor readings. Neighboring motes

pick up the transmissions and forward them to their

neighbors and so on, until the signals

arrive at the collection node and are transmitted to

the commander. The commander can

now display the data on a screen and see, in real

time, the path that the truck is following

through the field of motes. Then a remotely piloted

vehicle can fly over the truck, make

sure it belongs to the enemy and drop a bomb to

destroy it.

This might seem like a lot of trouble, but it is really

more effective than the



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solutions of the past. In the past, the tool a

commander used to prevent truck or troop

movement through a remote area has been land

mines. Soldiers would lace the area with

thousands of anti-truck or anti-personnel mines.

Anyone moving through the area -- friend

or foe -- is blown up. Another problem, of course, is

that long after the conflict is over the

mines are still active and deadly -- laying in wait to

claim the limbs and even lives of any

passerby. According to a UNICEF report, over thelast 30 years, landmines have killed or

maimed more than 1 million people -- many of

whom are children. With motes, what is left

behind after a war are tiny, completely harmless

sensors. Since motes consume so little

power, the batteries would last a year or two. Then,

the motes would simply go silent

presenting no physical threat to civilians nearby.

The following are some of

the ideas floating around that show a few of the ways

that smart does can affect our lives in

the future:

The monitoring of weather and seismology

Better prediction of earthquakes and

tornados.

The monitoring of environments on Mars and

other planets.

Internal spacecraft monitoring this can be

useful in preventing the shuttle from

crashing due to technical problems by finding them

before they occur.

Land to space communication networks

faster communication from earth to space

with real time data.

Chemical and biological sensors - could be

used to monitor the purity of drinking or

sea water, to detect hazardous chemical or biological

agents in the air or to locate

and destroy tumor cells in the body

Inventory Control Know where your

products are and what shape they're in any

time, anywhere. Sort of like FedEx tracking on

steroids for all products in your

production stream from raw materials to delivered

goods.

Product quality monitoring smart dust canhave many positive effects on quality

control: Temperature, humidity monitoring of meat,

produce, dairy products, etc.

Smart offices and smart homes

environmental conditions in the office or home are

tailored to the desires of every individual.

Sports smart dust could bring a whole new

aspect to sporting events. Sailboat

racers can monitor the changes in the wind and

current to gain an advantage. Also,

think about the possibilities of putting motes on the

balls during games to monitor



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things such as ball spin and speed.



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Typical Applications

If you survey the literature for different ways that

people have thought of to use motes, you find a huge

assortment of ideas. Here's a collection culled from

the links at the end of the article.

It is possible to think of motes as lone sensors. For

example:

You could embed motes inbridges when you

pour the concrete. The mote could have a

sensor on it that can detect the salt

concentration within the concrete. Then once

a month you could drive a truck over the

bridge that sends a powerful magnetic field

into the bridge. The magnetic field would

allow the motes, which are burried within the

concrete of the bridge, to power on and

transmit the salt concentration. Salt (perhaps

from deicing or ocean spray) weakens

concrete and corrodes the steel rebar that

strengthens the concrete. Salt sensors would

let bridge maintenance personnel gauge how

much damage salt is doing. Other possible

sensors embedded into the concrete of a

bridge might detect vibration, stress,

temperature swings, cracking, etc., all of

which would help maintenance personnel

spot problems long before they become

critical.

2You could connect sensors to a mote that

can monitor the condition of machinery --

temperature, number of revolutions, oil level, etc.

and log it in the mote's memory. Then, when a truck

drives by, the mote could transmit all the logged

data. This would allow detailed maintenance records

to be kept on machinery (for example, in an oil

field), without maintenance personnel having to go

measure all of those parameters themselves. You could attach motes to the water meters

or power meters in a neighborhood. The motes

would log power and water consumption for a

customer. When a truck drives by, the motes get a

signal from the truck and they send their data. This

would allow a person to read all the meters in a

neighborhood very easily, simply by driving down

the street.

All of these ideas are good; some allow sensors to

move into places where they have not been before

(such as embedded in concrete) and others reduce

the time needed to read sensors individually.

This concept of ad hoc networks -- formed byhundreds or thousands of motes that communicate

with each other and pass data along from one to

another -- is extremely powerful. Here are several

examples of the concept at work:

http://www.howstuffworks.com/bridge.htmhttp://www.howstuffworks.com/bridge.htm


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Imagine a suburban neighborhood or an

apartment complex with motes that monitor the

water and power meters (as described in the previous

section). Since all of the meters (and motes) in a

typical neighborhood are within 100 feet (30 meters)

of each other, the attached motes could form an ad

hoc network amongst themselves. At one end of the

neighborhood is a super-mote with a network

connection or a cell-phone link. In this imagined

neighborhood, someone doesn't have to drive a truck

through the neighborhood each month to read theindividual water or power meters -- the motes pass

the data along from one to another, and the super-

mote transmits it. Measurement can occur hourly or

daily if desired.

A farmer, vineyard owner, or ecologist could

equip motes with sensors that detect temperature,

humidity, etc., making each mote a mini weatherstation. Scattered throughout a field, vineyard or

forest, these motes would allow the tracking of

micro-climates.

A building manager could attach motes to

every electrical wire throughout an office building.

These motes would have induction sensors to detect

power consumption on that individual wire and let

the building manager see power consumption down

to the individual outlet. If power consumption in the

building seems high, the building manager can track

it to an individual tenant. Although this would be

possible to do with wires, with motes it would be far

less expensive.

8.A biologist could equip an endangered

animal with a collar containing a mote that senses

position, temperature, etc. As the animal moves

around, the mote collects and stores data from the

sensors. In the animal's environment, the biologists

could place zones or strips with data collection

motes. When the animal wanders into one of these

zones, the mote in the collar would dump its data to

the ad hoc network in the zone, which would then

transmit it

A forest service could use smart dust tomonitor for fires in a forest (Eng 2004). In this

scenario, forest service personnel would drop the dust

from an airplane and then count on the sensors to

self-organize into a network. In the event of a fire, a

mote that notices unusual temperatures in its zone

would alert neighboring notes that would in turn

notify other motes in the network. In this way the

network of motes would notify a central monitoring

station of the fire and the location of the mote that

noticed it. Equipped with prompt notice of the fire

and its approximate location, firefighters could race

to the scene and fight the fire while it is small. By

linking similar networks of motes to a central fire

reporting system, the system can be extended to

monitor an enormous region in a national forest.

Motes will be applied in industrial settings to

reduce plant downtime and enhance safety. Consider

the scenario of a chemical plant that utilizes pipes to

transport acidic or abrasive liquids. The chemical

contents of the pipes can gradually weaken them so,



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SMART DUST 2010

to prevent accidental chemical releases, plant

operators must periodically inspect piping and other

components that may be susceptible to wall

thinning caused by erosion/corrosion

(Jonas1996). Today, this inspection process is labor

intensive for pipes covered with insulation and for

pipes located in confined areas. In the future, smart

dust could be employed to facilitate

inspections. With this, a plant operator would place

several corrosion-detecting motes on

piping throughout the plant and then configure acentral monitoring station to receive status

updates from the motes. And because the motes can

be installed under pipe insulation, plant

personnel would no longer need to manually remove

insulation to evaluate the condition of a

pipe (Gibbons-Paul 2004). With this system, the

plant manger benefits from having up-to-date

status information of all piping while avoiding the

costs of manual inspections.

In business, smart dust will be applied in similar

innovative ways to improve services and save money.

One such scenario involves a local lighting and

power organization. Today, in order to

determine which of thousands of street lights, are out

or in need of service the power company

periodically surveys the lights after sunset or waits

for a customer complaint. But imagine if

the organization monitored its service area with

thousands of cheap, light-sensor equipped

motes. The firm can now immediately pinpoint the

location of non-working lights without

incurring the labor and transportation costs of a

physical survey. Repairs can be organized in a

more systematic manner, complaint calls can be

reduced, and customers will be more satisfied

Motes placed every 100 feet on a highway

and equipped with sensors to detect traffic flow

could help police recognize where an accident has

stopped traffic. Because no wires are needed,



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5 Issues

The development and use of smart dust raises some

issues and concerns for stakeholders.

These include privacy issues, potential system

security weaknesses, the need for standards, and

the environmental impacts of smart dust. Each of

these issues is discussed below.

5.1 Privacy

Its easy to imagine that tiny smart dust sensors could

be used for mischievous, illegal, or

unethical purposes. Corporations, governments, and

individuals could use motes to monitor

people without their knowledge. And smart dust

could become the tool of choice for corporate

espionage. Privacy issues such as these have been

raised before. In one case, during an

interview with smart dust inventor Kris Pister, a

reporter asked about the

dark side

of the technology. Dr. Pister replied,

I believe that the benefits will far, far outweigh the

drawbacks,but Im hardly unbiased.These issues are

not easily resolved, but as smart dust becomes

smaller, cheaper, and more prevalent, privacy

concerns are likely to increase.

5.2 Security

Smart dust motes, as networked computing devices,are susceptible to security concerns similar

to that of computers on the Internet. One of these

susceptibilities is due to the fact that motes in

a network are reprogrammable. This feature allows

an administrator to update the software on

a single mote and then command it to pass the update

along to all the other motes in the

network (Culler and Mulder 2004). Although the

mote identity verification algorithms in the

TinyOS operating system would make it difficult,

this mote software feature could be exploited

by hackers and eavesdroppers (ibid). In applications

that gather sensitive data, system

designers should be aware that there is a risk that the

data could be compromised.

5.3 Standards

As interest in smart dust increases and more

manufacturers produce motes, end users will have

more choices when building a system. However, not

all smart dust devices would work



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SMART DUST 2010

effectively together without standards. Fortunately, a

set of standards is forthcoming -- an

alliance of industry leaders has proposed the ZigBee

standards (Economist 2004). Once

10

agreed upon by industry and released by the Institute

of Electrical and Electronics Engineers

(IEEE), the standards will apply to

residential, industrial, and building controls

(ibid). And

the alliance is well positioned to draft additionalstandards should the need arise due to the

discovery of new applications for the technology.

5.4 Environmental Impacts

After smart dust is sprinkled in a remote or desolate

area to accomplish a monitoring function, it is not

easily or inexpensively retrieved. If a mote fails and

is consequently abandoned by its

owner, there is an environmental impact. A motes

environmentally unfriendly components

include integrated circuits, a battery, and a printed

circuit board. Clearly, motes have

environmental impacts that should be considered by

users. It is somewhat ironic that negative

environmental consequences could arise from the use

of smart dust for an environmentally

sound purpose such as protecting a forest from fires.

ZigBee is named after the zigging and zagging of

bees, which are individually simple organisms that

work

10

together to tackle complex tasks



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SMART DUST 2010

REFERENCES

P.B.Chu , KSJ Pister optical

communication using micro corner cube

reflectors 10th IEEE Intl Workshop on

Micro Electro Mechanical Systems

J . Kahn , R.H.Katz, KSJ Pister Mobile

Networking for Smart Dust

W. Dabbous, E. Duros, T. Ernst, Dynamic

Routing in Networks with Unidirectional

Links, Workshop of Satellite-Based

Information Systems, Budapest,

(September1997).

F. Gfeller and W. Hirt, A Robust Wireless

Infrared

D. Goodman, Wireless Personal

Communication Systems, Addison-Wesley

Longman, Reading, MA,1997.

V. S. Hsu, J. M. Kahn, and K. S. J. Pister,

Wireless Communications for Smart Dust,

Electronics Research Laboratory

Memorandum Number M98/2, 1998.

http://www.janet.ucla.edu/WINS.

http://www.research.digital.com/wrl/projects/

Factoid/index.html.

http://www-

mtl.mit.edu/~jimg/project_top.html.

J. Jubin, J. D. Turnow, The DARPA Packet

Radio

G. S. Lauer, Packet-Radio Networks,

Chapter 11 in

8. CONCLUSION

Smart Dust, is an integrated approach to networks of

millimeter-scale

sensing/communicating nodes. Smart Dust can

transmit passively using novel optical

reflector technology. This provides an inexpensiveway to probe a sensor or acknowledge

that information was received. Active optical

transmission is also possible, but consumes

more power. It will be used when passive techniques

cannot be used, such as when the line



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SMART DUST 2010

of-sight path between the dust mote and BTS is

blocked.

Smart dust provides a very challenging platform in

which to investigate applications

that can harness the emergent behavior of ensembles

of simple nodes. Dealing with partial

disconnections while establishing communications

via dynamic routing over rapidly

changing unidirectional links poses critical research

challenges for the mobile networking

community

easy way to comply with the conference paper formattingrequirements is to use this document as a template and simplytype your text into it.

Pa All paragraphs must be indented. All paragraphs mustbe justified, i.e. both left-justified and right-justified.

A. ge Layout

Your paper must use a page size corresponding to A4which is 210mm (8.27") wide and 297mm (11.69") long. Themargins must be set as follows:

Top = 19mm (0.75")

Bottom = 43mm (1.69")

Left = Right = 14.32mm (0.56")Your paper must be in two column format with a space of

4.22mm (0.17") between columns.

I. PAGE STYLE

All paragraphs must be indented. All paragraphs must bejustified, i.e. both left-justified and right-justified.

A. Text Font of Entire Document

The entire document should be in Times New Roman orTimes font. Type 3 fonts must not be used. Other font typesmay be used if needed for special purposes.

Recommended font sizes are shown in Table 1.[1] J. Breckling, Ed., The Analysis of Directional Time Series: Applications

to Wind Speed and Direction, ser. Lecture Notes in Statistics. Berlin,Germany: Springer, 1989, vol. 61.

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[3] M. Wegmuller, J. P. von der Weid, P. Oberson, and N. Gisin, Highresolution fiber distributed measurements with coherent OFDR, inProc. ECOC00, 2000, paper 11.3.4, p. 109.

[4] R. E. Sorace, V. S. Reinhardt, and S. A. Vaughn, High-speed digital-to-RF converter, U.S. Patent 5 668 842, Sept. 16, 1997.

[5] (2002) The IEEE website. [Online]. Available: http://www.ieee.org/[6] M. Shell. (2002) IEEEtran homepage on CTAN. [Online]. Available:

http://www.ctan.org/tex-archive/macros/latex/contrib/supported/IEEEtran/

[7] FLEXChip Signal Processor (MC68175/D), Motorola, 1996.[8] PDCA12-70 data sheet, Opto Speed SA, Mezzovico, Switzerland.[9] A. Karnik, Performance of TCP congestion control with rate feedback:

TCP/ABR and rate adaptive TCP/IP, M. Eng. thesis, Indian Institute ofScience, Bangalore, India, Jan. 1999.

[10] J. Padhye, V. Firoiu, and D. Towsley, A stochastic model of TCP Renocongestion avoidance and control, Univ. of Massachusetts, Amherst,MA, CMPSCI Tech. Rep. 99-02, 1999.

[11] Wireless LAN Medium Access Control (MAC) and Physical Layer(PHY) Specification, IEEE Std. 802.11, 1997.

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