wireless ad-hoc sensor networks for monitoring endangered plant species edo biagioni university of...
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Wireless Ad-Hoc Sensor Networks forWireless Ad-Hoc Sensor Networks forMonitoring Endangered Plant SpeciesMonitoring Endangered Plant Species
Edo BiagioniEdo Biagioni
University of Hawaii at ManoaUniversity of Hawaii at ManoaAlso Kim Bridges, Brian Chee, Anders Host-Madsen, Also Kim Bridges, Brian Chee, Anders Host-Madsen, Galen Sasaki, and many more, including Chen, Fan, Galen Sasaki, and many more, including Chen, Fan, Morton, Xie, and DARPAMorton, Xie, and DARPA
OverviewOverview
An ecological wireless sensor An ecological wireless sensor networknetwork
Overall challengesOverall challenges
Current solutionsCurrent solutions
Future solutionsFuture solutions
Protecting Endangered Protecting Endangered PlantsPlants
Hard to do Hard to do without knowing without knowing plants' needs, soplants' needs, so
Study the Study the environmentenvironment
See how the See how the plants are doingplants are doing
Use sensors and Use sensors and hi-res camerashi-res cameras
ChallengesChallengesEnergy: batteries, solar, windEnergy: batteries, solar, wind
Sleep, wake up, transmit, go back to Sleep, wake up, transmit, go back to sleepsleep
Low bit-rate, but over a wide areaLow bit-rate, but over a wide area
Low cost, unobtrusiveLow cost, unobtrusive● Fading: bad geometry, plants (2.4GHz)Fading: bad geometry, plants (2.4GHz)● Collisions and CongestionCollisions and Congestion● Sensors: sunlight, rain, windSensors: sunlight, rain, wind
• Issues common to most sensor Issues common to most sensor networks!networks!
The PODS projectThe PODS project
Hawaii: endangered species “capital”Hawaii: endangered species “capital”
Microclimates: rapid weather changesMicroclimates: rapid weather changes
Pods communicate over many hops Pods communicate over many hops with internet-connected base stationwith internet-connected base station
Assembly of COTS hardware (IPAQ w/ Assembly of COTS hardware (IPAQ w/ Linux), 802.11Linux), 802.11
Custom software, protocols: MOR, LususCustom software, protocols: MOR, Lusus
Transmission range typically ~ Transmission range typically ~ PowerPower--44
Pod placementPod placement
Intensive deployment Intensive deployment where plant growswhere plant grows
Also interested in where Also interested in where the plant does the plant does notnot grow grow
Connection to the Connection to the internet is also a line of internet is also a line of sensorssensors
Many interesting Many interesting topologies [Biagioni and topologies [Biagioni and Sasaki, 2003]Sasaki, 2003]
Sub-region
Ad-hoc Wireless Ad-hoc Wireless Communication:Communication:
Multipath On-Demand RoutingMultipath On-Demand RoutingProtocol provides routing information Protocol provides routing information as well as transport for data (IP) as well as transport for data (IP) packetspackets
Multiple paths with retransmission Multiple paths with retransmission perform well in the face of congestion – perform well in the face of congestion – good performance means low powergood performance means low power
Application-level broadcast supports Application-level broadcast supports synchronizationsynchronization
Low or high mobilityLow or high mobility
Sensor Network ArchitectureSensor Network Architecture
More powerful pods form a “backbone”, More powerful pods form a “backbone”, may have better communications and may have better communications and sensors (cameras), may be always onsensors (cameras), may be always on
Smaller sensors are cheaper, use less Smaller sensors are cheaper, use less energy, may have less range and lower energy, may have less range and lower speedspeed
Two-tiered (or multi-tiered) architectureTwo-tiered (or multi-tiered) architecture
Protocol for Simple NodesProtocol for Simple NodesLususLusus
Routing on a gradient towards base Routing on a gradient towards base station or nearest high-level nodestation or nearest high-level node
Link-layer reliabilityLink-layer reliability
Joining separate data into one packetJoining separate data into one packet
Low speed serial radiosLow speed serial radios
PIC microcontrollerPIC microcontroller
Application-Level Data Application-Level Data Protocol:Protocol:
SNDTSNDTFeatures:Features:
ReliableReliable
Low-overheadLow-overhead
EncryptionEncryption
Faster than using SSH/TCP to transfer Faster than using SSH/TCP to transfer small amounts of datasmall amounts of data
Rate-limited transmissionRate-limited transmission
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Cooperative DiversityCooperative DiversityAnders Host-MadsenAnders Host-Madsen
Ad-hoc networksAd-hoc networks
Users communicate directly with Users communicate directly with each othereach other
Interference Among Different Interference Among Different connectionsconnections
Fading due to distanceFading due to distance
– Fading
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Cooperative TDMACooperative TDMA
Cooperative TDMACooperative TDMA
Nodes use TDMA multiple-accessNodes use TDMA multiple-access
While a transmitter is passive, it can act While a transmitter is passive, it can act as relayas relay
One node One node transmits first transmits first and the other and the other helps, then helps, then switchswitch
Research PlanResearch PlanAnders Host-MadsenAnders Host-Madsen
ResultsResultsFading Relay channel capacity (with J. Zhang, ASU)Fading Relay channel capacity (with J. Zhang, ASU)Theoretical bounds for 4-node cooperative diversityTheoretical bounds for 4-node cooperative diversityNSF fundingNSF funding
CurrentCurrentMIMO Relay Channel (with J. Zhang, ASU)MIMO Relay Channel (with J. Zhang, ASU)Multinode relay channelMultinode relay channelConstruction of experimental 4-node networkConstruction of experimental 4-node networkPractical coding methods for the relay channelPractical coding methods for the relay channel
FutureFutureLow power regimeLow power regimeExperimentation on wireless testbedExperimentation on wireless testbedGeneralization to larger networksGeneralization to larger networks
Routing/clusteringRouting/clustering
Application to environmental sensor networkApplication to environmental sensor network
Open Research IssuesOpen Research Issues
Theoretical models for wireless ad-hoc Theoretical models for wireless ad-hoc network performancenetwork performance
Practical, reproducible performance testsPractical, reproducible performance tests
Lessen power needs by moving away from Lessen power needs by moving away from COTS (or by COTS moving closer)COTS (or by COTS moving closer)
Micropower generation and conservationMicropower generation and conservation
Wireless that works well near the groundWireless that works well near the ground
Wireless Ad-Hoc Network Wireless Ad-Hoc Network PerformancePerformance
In typical multi-hop networks, at most 1 In typical multi-hop networks, at most 1 out of 3 nodes can transmit at any timeout of 3 nodes can transmit at any time
Interference range is usually greater Interference range is usually greater than transmission rangethan transmission range
Fading varies over time, and it is hard to Fading varies over time, and it is hard to reproduce any actual testreproduce any actual test
““Quantum” testing: observe what Quantum” testing: observe what actually happens, run in actual actually happens, run in actual environmentsenvironments
Power Research IssuesPower Research Issues
COTS keeps getting lower power, COTS keeps getting lower power, smaller, cheapersmaller, cheaper
Microcontrollers can do 90% of the job Microcontrollers can do 90% of the job at a fraction of the (cost, size, weight)at a fraction of the (cost, size, weight)
Solar works well, expensive, hard to Solar works well, expensive, hard to concealconceal
Wind works sometimes, hard to concealWind works sometimes, hard to conceal
Future WorkFuture Work
More applications: science, agriculture, More applications: science, agriculture, even tourismeven tourism
Better visualization of dataBetter visualization of data
Evaluation with larger actual networksEvaluation with larger actual networks
Protocol improvementsProtocol improvements
Better, lower power, less conspicuous, Better, lower power, less conspicuous, cheaper sensors and camerascheaper sensors and cameras
SummarySummary
Experience building, deploying wireless ad-Experience building, deploying wireless ad-hoc sensor networkshoc sensor networks
Multi-tiered sensor network architectureMulti-tiered sensor network architecture
Power may cost more than computer+sensorPower may cost more than computer+sensor
Most protocols work (e.g. MANET), but some Most protocols work (e.g. MANET), but some (e.g. MOR) may work better(e.g. MOR) may work better
Cooperative diversity improves range in a Cooperative diversity improves range in a flexible mannerflexible manner
Performance testing is difficult but essentialPerformance testing is difficult but essential