application.ppt

UUNIVERSITY OF NIVERSITY OF MMASSACHUSETTSASSACHUSETTS, A, AMHERST • MHERST • Department of Computer Science Department of Computer Science

Applications of Sensor Networks

Chen, WeifengGong, YingLiu, Xiaotao


Outline

Why sensor nets? Advantages Applications

Classifications of sensor nets Challenging issues

Common constraints Application-specific constraints

Discussions


Outline




Discussions


Intimate connection with its immediate environment.

Advantages of Sensor Nets



No disturbance to environment, animals, plants, etc.

Advantages of Sensor Nets (cont.)




Avoid unsafe or unwise repeated field studies.





Avoid unsafe or unwise repeated field studies.

Economical method for long-term data collection

One deployment, multiple utilizations



Habitat monitoring Environmental observation and

forecasting systems: Columbia River Estuary

Smart Dust Biomedical sensors

Applications of Sensor Nets


Petrel habitat on Great Duck Island in Maine.

Questions to answer: Usage pattern of nesting burrows

over the 24-72 hour cycle Changes in the burrow and surface

environmental parameters Differences in the micro-

environments with and without large numbers of nesting petrels

Primitive requirement: no human disturbance.

Habitat Monitoring


Approach to habitat monitoring


Estuarine Environmental Observation and Forecasting System

Observation and forecasting system for the Columbia River Estuary


CORIE Approach

Real-time observations Estuarine and offshore

stations Numerical modeling

Produce forecast, hindcast of circulation

Virtualization & application Vessel survey, navigation fishing, etc…


Smart Dust: Mote

1-2 mm

Thick-Film Battery

Solar Cell

Power Capacitor

Analog I/O, DSP, Control

Active Transmitter with Laser

Diode and Beam SteeringPassive Transmitter with

Corner-Cube Retroreflector

Sensors

Receiver with Photodetector

Tiny & light-communication


Military Applications of Smart Dust


Biomedical Sensors Sensors help to create vision


Outline




Discussions


Classifications of Sensor Nets Sensor position

Static (Habitat, CORIE, Biomedical) Mobile (Smart Dust, Biomedical)

Goal-driven Monitoring: Real-time/Not-real-time (Habitat, Smart

Dust) Forecasting (CORIE) Function substitution (Biomedical) …

Communication medium Radio Frequency (Habitat, CORIE, Biomedical) Light (Smart Dust)


Outline




Discussions


Common Challenging Issues Limited computation and data storage Low power consumption Wireless communication

Medium, ad hoc vs. infrastructure, topology and routing

Data-related issues Continuous operation Inaccessibility – network adjustment and

retasking Robustness and fault tolerance


Application-specific Constraints

Material Constraints Bio-Compatibility Inconspicuous

Imitative to environment Detect-proof: e.g. stealth flight

Secure Data Communications Regulatory Requirements – such

as FDA


Limited Computation and Data Storage

Sensor design Multi-objective sensors and single (a few)-objective sensors.

Cooperation among sensors Data aggregation and

interpretation


Low Power Consumption Low power functional components Power-manageable components

Several functional state (low state-transition overhead)

Deep-sleep, Sleep, On Provide different QoS with different power consumption.

Power Management Power measurement Power budget allocation Control transitions between different power states.


Wireless Communication

Communication mediums Radio Frequency: Habitat monitoring,

Biomedical sensors and CORIE estuarine observation

Light (active and passive): Smart Dust

Ad hoc versus infrastructure modes Topology Routing


Smart Dust: Passive Transmitters

Asymmetric Link assumed: high power laser emit from BS, with larger scale imaging array

DownlinkLaser

Uplink

CCD Corner-Cube

Uplink

DataIn

Data

ImageSensor

Retroreflector

DataIn

Photo-

DownlinkDataOut

detector

Base-StationTransceiver

DustMote

Signal Selectionand Processing

UplinkData ...

OutNOut1

Array

UnmodulatedInterrogation

ModulatedReflected

ModulatedDownlinkDataor

BeamforUplink

BeamforUplink

Lens

Lens


Smart Dust: Active Transmitter (cont.)

BS uses CCD or CMOS camera (operate at up to 1 Mbps) Using multi-hop routing, not all dust motes need LoS to BS

Transmitter Radiant IntensityReceiver Light Collection Area

Base

TransceiverStation

DustMote

DustMote

DustMote

Wall


Smart Dust: Active Transmitter

LaserCollimating

Beam

Mirror(s)

Lens

Steering

Diode

Two-axis beam steering assembly

Active dust mote transmitter Beams have divergence << 1º

Steerable over a full hemisphere


Ad hoc vs. Infrastructure Modes Sensor - Sensor communication:

Short distance Ad hoc

Sensor - Base station communication: Long distance sensor to base station

communication Infrastructure


Wireless Communication: Topology

Fixed topology Tree based Cluster based

Dynamic topology - mobility Ad hoc Infrastructure Mixed


Research on Fixed Topologies Vary # of neighbors Trade-offs exist

Number of hops Number of receivers Amount of contention

Evaluate power usage Test power-aware routing Results:

Power-aware routing reduces power usage

3D is better than 2D


Research on Fixed Topologies (cont.)

Cluster-based Tree-based

Cluster-based approach provides better energy-efficiency than the tree-based approach.


Wireless Communication: Routing

Route discovery Redundancy discovery Failure detection and recovery Distributed and localized

Avoid single-point failure Avoid bottleneck

Energy-efficient


Energy-Efficient Routing Protocol

Routing protocol metrics: Traditional: packet loss, routing

message overhead, routing length New metric: energy consumption:

, =2~4 Imagine:

dE

5

S T

M

5

9


Data-related issues Trade-off between latency and energy

Real-time Periodic

Data representation Raw/Compressed data Sampling Value: Absolute/Relative

Error calibration No access to real values Inferred from other sensors


Continuous Operation

Long-term data collection Renewable power source.

Solar energy Mechanical vibrations Radio-Frequency inductance Infrared inductance


Inaccessibility

Sensor location Embedded environment Avoid disturbance to sensing

objects Network adjustment Network retasking


Robustness and Fault Tolerance

Self-adaptive sensors: Adapted to the environment changes. Adapted to the power change.

Distributed network: Each sensor operate autonomously from

neighbors. Overlapped services area. No single point of failure.

Health and status monitoring E.g. reporting power along data transmission


Outline




Discussions


Discussions Unique solution to all applications exists? Most important considerations in designing:

Cost? Resource allocation? Manageability? Timeliness? Retasking? …

Scalability? Millions of sensor nodes?

Next generation sensor nets?


The EndThe EndThank you

Technology

application.ppt