Applications of Sensor Networks

Applications of Sensor Networks Chen, Weifeng Gong, Ying Liu, Xiaotao

Outline • Why sensor nets? • Advantages • Applications • Classifications of sensor nets • Challenging issues • Common constraints • Application-specific constraints • Discussions

Intimate connection with its immediate environment. Advantages of Sensor Nets

Intimate connection with its immediate environment. No disturbance to environment, animals, plants, etc. Advantages of Sensor Nets (cont.)

Intimate connection with its immediate environment. No disturbance to environment, animals, plants, etc. Avoid unsafe or unwise repeated field studies. Advantages of Sensor Nets (cont.)

Intimate connection with its immediate environment. No disturbance to environment, animals, plants, etc. Avoid unsafe or unwise repeated field studies. Economical method for long-term data collection One deployment, multiple utilizations Advantages of Sensor Nets (cont.)

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 • Tiny & light-communication

Military Applications of Smart Dust

Biomedical Sensors • Sensors help to create vision

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)

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

ModulatedDownlinkDataor BeamforUplink BeamforUplink Smart Dust: Passive Transmitters UnmodulatedInterrogation Lens Photo- detector Downlink Laser Downlink DataIn DataOut Uplink Signal Selection and Processing DataIn CCD Corner-Cube Image Lens Retroreflector ModulatedReflected Sensor Array DustMote Uplink Uplink ... Data Data Asymmetric Link assumed: high power laser emit from BS, with larger scale imaging array Out Out 1 N Base-StationTransceiver

Dust Mote Base Station Transceiver Dust Mote Transmitter Radiant Intensity Dust Receiver Light Collection Area Mote Wall 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

Smart Dust: Active Transmitter 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: M 5 5 S T 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

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 End Thank you

Applications of Sensor Networks