2007 sensor networks

8/8/2019 2007 Sensor Networks

http://slidepdf.com/reader/full/2007-sensor-networks 1/31

Taking Sensor Networks from

the Lab to the Jungle

Vamshi NadipelliPreethi Tiwari

ECE-695

Mobile Wireless Networks



02/6/07 2

W hat is a Sensor Network?

A sensor network is a collection of sensor nodes

equipped with sensing, communication (short range

radio) and processing capabilities.



02/6/07 3

Outline

IntroductionThe System

Areas of ApplicationChallenges

TechnicalSystem

Conclusion



02/6/07 4

IntroductionChain Home - B ritain¶s Radar Network WW II

Cold War:SOSUS ± The Pacific Ocean

N ORAD ± Cheyenne MountainNational Power GridInvolves

Devices with multiple sensorsNetwork via wireless/physical links



02/6/07 6

The Systems involved

Sensor Node Internals

Operating System



02/6/07 7

Sensor Node Internals

SENSOR

POWERSUPPLY

CPU

COMMUN ICAT ION

NODE

ELECTRO-MAGNETICINTERFACE

Some Current Node Platforms:

1. Sensoria WINS

2. Smart Dust ± Dust Inc. Berkeley

3. UC Berkeley mote ± Crossbow (www.xbow.com)



02/6/07 8

Op erating System - Tiny OS

Custom built at UC, B erkeley for wirelesssensor nodesComponent -based architecture: ensuresminimum code sizeComponent library includes:

Network protocolsSensor drivers

Data acquisition toolsDistributed services



02/6/07 9

Physical Size

AWACS

LWIM III AWAIRS IWINS

NG 2.0

Berkley

Motes



02/6/07 10

Applications

B order MonitoringB attlefield Observation

Forest Fire DetectionEnvironment and Habitat MonitoringInfrastructure securityIndustrial sensing

Medical Applications



02/6/07 11

Border Monitoring Most widely cited application

US -Mexico B order (3100 km)Requires Full length Surveillance

Detection can be based onsound or vibration

With in a range of 10m

Estimated need of 440,000sensors

Air dropped biannually (battery life

6months)Not cost effectiveShould distinguish humans fromwild animals



02/6/07 13

Battlefield surveillance

Observing enemy activities in a battle field.Unmanned aerial vehicles (UAV)

Coverage problem (limited radio range)

10,000 nodes were required to monitor just 1 squarekilometer

For large areas:

cost

Many nodes implies large number of UAV¶s operatingsimultaneously.



02/6/07 14



02/6/07 15

Forest Fire Detection

A sensor network is more feasible as an early warning system for

forests.

Carefully placing nodes (close to vulnerable areas such as hilltops)

Reduce the number of sensors required to cover a large geographic

area.

Important aspect is lifetime

Must operate for a very long period of time to discover a

comparatively rare event



02/6/07 16

Nodes are subjected to random failures

Due to battery exhaustion

Disorientation of antennas (falling branches, wind etc)

So, Networks relay messages hop by hop failure of severalclosely spaced nodes could partition the network into non

communicating subnetworks



02/6/07 17

Environment and Habitat Monitoring

Environmental monitoring involves collecting readings over time across a

volume of large space enough to exhibit significant internal variation.

Environmental sensors are used to monitor relative humidity, barometricpressure and temperature.

They study vegetation responses related to climatic trends and diseases

Whereas the imaging sensors can identify, track and measure the populationof birds and other species.



02/6/07 18

Monitoring nesting

Large number of burrows.

Long time observation



02/6/07 20

Migration pattern of zebrasThey generally move in wide areaLong term observation



02/6/07 22

I nfrastructure Security

Early detection of chemical, biological and nuclear threats.

Protection of power plants and communication centers.

Networks of video, acoustic and other sensors are deployed around thesefacilities.

When compared to Fixed sensors, Ad hoc networks can provide moreflexibility and additional coverage.

MULT IPLE SENSORS provide Improved coverage, detection, and reducedfalse alarm rate.



02/6/07 23



02/6/07 24

Industrial Sensing

Goals of commercial industryLower costImproved performanceMaintainability

It involves continuous monitoring of vibrations, lubrication levels and insertinsensors into regions inaccessible by humans.

Spectral and Optical sensors are generally used in industrial applications

because inputs from hundreds or thousands of sensors can be fed into thedatabases that can be accessed in any number of ways to show the real tim

information (called MULT IPO INT OR MATR IX SENS ING ).



02/6/07 25

Medical applications

Heart rateOxygen saturationEnhances emergency

medical care.



02/6/07 27

Technical challenges

Changing network topology:Node failuresIntroduction of additional nodes variations in sensor locationChanges to cluster allocations in response to network demandsrequires the adaptability of underlying network structures and

operations.

Advanced communication protocolsTo support high level services and real - time operation

(to adapt rapidly to changes in network conditions).

Resource optimization:To minimize cost, power and network traffic loadsEnsuring network reliability and adequate sensor resolution for dataaccuracy.



02/6/07 28

Limitations:Power, Memory, processing power, life - time. These physical constraints

may be minimized through further technological breakthroughs inmaterials and sensor hardware designs.

Failure prone :Individual sensors are unreliable, particularly in harsh and unpredictableenvironments.

Addressing sensor reliability can reduce the level of redundancyrequired for a network to operate with the same level of reliability.

Network congestion resulting from dense network

deployment :The quantity of data gathered may exceed the requirements of thenetwork and so evaluation of the data and transmission of only relevantand adequate information needs to be performed.



02/6/07 29

Self-organization

Ability to adapt to dynamic environments as well as ad hoc distributionand connectivity scenarios.

Self-operating and self-maintaining

This functionality is desired in order to minimize further humaninteraction beyond network deployment.

Security

It is a critical factor in sensor networks.

An effective compromise must be obtained, between the low bandwidthrequirements of sensor network applications and security demands.



02/6/07 30

Conclusion

Sensor networks are application specific

Key application characteristics

Lifetime, cost, data rate, environment, network

topology, user interaction

Must address the system aspects of wireless sensor network design



02/6/07 31

QU EST ION S

?

2007 sensor networks

Documents