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Wireless Sensor Networks for Habitat Monitoring. Alan Mainwaring 1 Joseph Polastre 2 Robert Szewczyk 2 David Culler 1,2 John Anderson 3 1: Intel Research Laboratory at Berkeley 2: University of California, Berkeley 3: College of the Atlantic. Introduction.

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Wireless sensor networks for habitat monitoring

Wireless Sensor Networksfor Habitat Monitoring

Alan Mainwaring1

Joseph Polastre2

Robert Szewczyk2

David Culler1,2

John Anderson3

1: Intel Research Laboratory at Berkeley

2: University of California, Berkeley

3: College of the Atlantic


Introduction
Introduction

  • Application Driven System Design, Research, and Implementation

  • Parameterizes Systems Research:

    • Localization

    • Calibration

    • Routing and Low-Power Communications

    • Data Consistency, Storage, and Replication

  • How Can All of these Services and Systems Be Integrated into a Complete Application?


Great duck island
Great Duck Island

  • Breeding area for Leach’s Storm Petrel (pelagic seabird)

  • Ecological models may use multiple parameters such as:

    • Burrow (nest) occupancy during incubation

    • Differences in the micro-climates of active vs. inactive burrows

    • Environmental conditions during 7 month breeding season


Application
Application

> 1000 ft



Outline
Outline

  • Application Requirements

  • Habitat Monitoring Architecture

    • Sensor Node

    • Power Management

    • Sensor Patch

    • Transit Network

    • Wide Area Network and Disconnected Operation

  • Sensor Data

  • System Analysis

  • Real World Challenges


Application requirements
Application Requirements

  • Sensor Network

    • Longevity: 7-9 months

    • Space: Must fit inside Small Burrow

    • Quantity: Approximately 50 per patch

    • Environmental Conditions

    • Varying Geographic Distances

  • Inconspicuous Operation

    • Reduce the “observer effect”

  • Data

    • As Much as Possible in the Power Budget

    • Iterative Process


Application requirements1
Application Requirements

  • Predictable System Behavior

    • Reliable

    • Meaningful Sensor Readings

  • Multiple Levels of Connectivity

    • Management at a Distance

    • Intermittent Connectivity

    • Operating Off the Grid

    • Hierarchy of Networks / Data Archiving


Habitat monitoring architecture

Patch

Network

Sensor Node

Sensor Patch

Gateway

Transit Network

Internet

Client Data Browsing

and Processing

Basestation

Base-Remote Link

Data Service

Habitat Monitoring Architecture


Sensor node mica
Sensor Node: Mica

  • Hardware

    • Atmel AVR w/ 512kB Flash

    • 916MHz 40kbps Radio

      • Range: max 100 ft

      • Affected by obstacles, RF propogation

    • 2 AA Batteries

      • Operating: 15mA

      • Sleep: 50mA

  • Software

    • TinyOS / C Applications

    • Power Management

    • Digital Sensor Drivers

    • Remote Management & Diagnositcs


Sensor node power management
Sensor Node: Power Management

  • AA Batteries have ~2500 mAh capacity

  • Mica consumes 50mA in sleep = 1.2 mAh/day

Mica Expected Lifetime

Expected Lifetime (days)

Number of Operating Hours per Day


Sensor node power management1
Sensor Node: Power Management

  • Target Lifetime: 7-8 months

  • Power Budget: 6.9mAh/day

  • Questions:

    • What can be done?

    • How often?

    • What is the resulting sample rate?


Sensor node mica weather board
Sensor Node: Mica Weather Board

  • Digital Sensor Interface to Mica

    • Onboard ADC

  • Designed for Low Power Operation

    • Individual digital switch for each sensor

  • Designed to Coexist with Other Sensor Boards

    • Hardware “Enable” Protocol to obtain exclusive access to connector resources


Sensor node mica weather board1

Important to Biologists

Affect Power Budget

Sensor Node: Mica Weather Board


Sensor node packaging
Sensor Node: Packaging

  • Parylene Sealant

  • Acrylic Enclosures


Sensor patch network
Sensor Patch Network

  • Nodes:

    • Approximately 50

    • Half in burrows, Half outside

    • RF unpredictable

      • Burrows

      • Obstacles

      • Drop packets or retry?

  • Transmit Only Network

  • Single Hop

  • Repeaters

    • 2 hop initially

    • Most Energy Challenged

  • Adheres toPower Budget


Transit network
Transit Network

  • Two implementations

    • Linux (CerfCube)

    • Relay Mote

  • Antennae

    • No gain antenna (small)

    • Omnidirectional

    • Yagi (Directional)

  • Implementation of transit network depends on:

    • Distance

    • Obstacles

    • Power Budget

  • Duty cycle of sensor nodes dictates transit network duty cycle


Transit network1
Transit Network

  • Renewable Energy Sources

    • CerfCube needs 60Wh/day

    • Assuming an average peak of 1 direct sunlight hour per day:

    • Panel must be 924 in2or 30” x 30” for a 5” x 5” device!

    • A mote only needs 2Wh per day, or a panel 6” x 6”


Base station wide area network
Base Station / Wide Area Network

  • Disconnected Operation and Multiple Levels of State

    • Laptop

      • DirecWay Satellite WAN

      • PostgreSQL

      • 47% uptime

    • Redundancy and Replication

      • Increase number of points of failure

    • Remote Access

      • Physical Access Limited

  • Keep state all areas of network

  • Resiliency to

    • Disconnection

    • Network Failures

    • Packet Loss

  • Potential Solution:Keep Local CachesSynchronization



Sensor data analysis1
Sensor Data Analysis

Outside Burrow

Inside Burrow


System analysis

Power Management Goals

Calculated 7 months, expect 4 months

Battery half-life at 1.2V

Predictable Operation

Observed per node constant throughput, % loss

739,846 samples as of 9/23, network is still running

System Analysis

Battery Consumption at Node 57

Packet Throughput and Active Nodes


Real world experiences
Real World Experiences

  • System and Sensor Network Challenges

    • Low Power Operation (low duty cycle)

      • Affects hardware and software implementation

    • Multihop Routing

      • Allows bigger patches

      • Route around physical obstacles

      • Must have ~1% operating duty cycle

    • In Situ Retasking/Reconfiguration

      • Let biologists interactively change data collection patterns

      • Not Implemented due to conservative energy implementation

    • Lack of Physical Access

      • Remote management

      • Disconnected operation

      • Fault tolerance

      • Reliance on other people and their networks

    • Physical Size of Device

      • Affects microcontroller selection, radio, practical choice of power sources


Real world experiences1
Real World Experiences

  • Failures

    • Extended Loss of Wide Area Connectivity

    • Unreliable Reboot Sequence in Windows

    • Solderless Connections Fail (expansion/contraction cycles)

    • Node Attrition (Petrels are not mote neutral)

    • Environmental Conditions (50km/hr gale winds knock over equipment)

    • Lack of post-mortem diagnositics


Conclusions
Conclusions

  • First long term outdoor wireless sensor network application

  • Application driven sensor network design

    • Defines requirements and constraints on core system components (routing, retasking, fault tolerance, power management)









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