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CSE 5392 Sensor Network Security. Introduction to Sensor Networks. Communication and processing module. sensor. An Application of Sensor Networks. 1. Network protocol (e.g., routing). 2. Data management (e.g., aggregation). 3. Localization and time synchronization. - PowerPoint PPT Presentation
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CSE 5392 By Dr. Donggang Liu 1
CSE 5392 Sensor Network Security
Introduction to Sensor Networks
CSE 5392 By Dr. Donggang Liu 2
An Application of Sensor Networks
sensor
Communication and processing
module
1. Network protocol (e.g., routing)2. Data management (e.g., aggregation)3. Localization and time synchronization4. Energy management, robustness, etc.
CSE 5392 By Dr. Donggang Liu 3
Sensor Node: Mica2
• Hardware– Processor: Atmega128L 4Mhz, 8-bit– Memory: 4K RAM, 512kB Flash– Communication: 19.2kbps Radio– Power supply: 2 AA Batteries
• Software – TinyOS / NesC Applications– Network management– Power management– Sensor drivers– Security package (TinySec)
CSE 5392 By Dr. Donggang Liu 4
Sensing Capabilities
• Many types of sensors that are able to monitor:– Temperature– Humidity– Light– Pressure– Noise levels– The presence or absence of certain kinds of objects– Movement (speed, direction) of an object
CSE 5392 By Dr. Donggang Liu 5
Military Applications
• Battlefield surveillance
• Monitoring friendly forces, equipment and ammunition
• Reconnaissance of opposing forces and terrain
• Target tracking
• Battle damage assessment
• Nuclear, biological and chemical attack detection and reconnaissance
CSE 5392 By Dr. Donggang Liu 6
Civilian Applications
• Forest fire detection
• Biocomplexity mapping of the environment
• Flood detection
• Precision Agriculture: the pesticides level in the drinking water, soil erosion, and air pollution.
• Smart environment, smart kindergarten, and more
CSE 5392 By Dr. Donggang Liu 7
Features of Sensor Networks
• Fault tolerance
• Scalability
• Production costs
• Hardware constraints
• Sensor network topology
• Transmission media
• Power consumption
CSE 5392 By Dr. Donggang Liu 8
Fault Tolerance
• Failures due to:– lack of power– physical damage in harsh environment– Interference by other objects (e.g. radios) and other
sensors.
• Fault tolerance: the ability to maintain sensor network functionalities in the presence of failures
• The environment is important to the fault tolerance of algorithms and protocols
CSE 5392 By Dr. Donggang Liu 9
Scalability
• Number of sensors: hundreds, thousands, to millions, depending on the applications.
• The density of the network usually depends on the applications
• Typically, people consider a large number of sensor nodes densely deployed in a target field.
CSE 5392 By Dr. Donggang Liu 10
Costs
• Per node cost is important for large sensor networks. It has to be kept low.
• Bluetooth radio system: $5 now, but still too expensive for sensors. PicoNode: targeted to be < 50c.
• More challenging, with large amount of functionalities
• Reality: $150 for one Micaz mote
CSE 5392 By Dr. Donggang Liu 11
Resource Constraints (Mica2)
• Processor: 8-bit 4MHz CPU (no division)
• Limited memory: 4K RAM
• Low bandwidth: 19.2K bps
• Small packet size: 29-byte long payload
• Limited energy supply: Battery powered
• Many traditional techniques are not practical
CSE 5392 By Dr. Donggang Liu 12
Network Topology
• Sensor networks are usually formed in an ad hoc manner• Topology maintenance is a challenging task due to
– Number of nodes, failures, dynamics etc• Pre-deployment and deployment phase
– Reduce the installation cost,– Eliminate the need for any pre-organization and pre-planning– Increase the flexibility of arrangement– Provide better self-organization and fault tolerance.
• Post-deployment phase– Topology may changes are due to node movement, lack of energy,
node malfunctioning, etc• Re-deployment of additional nodes phase
– Adding new sensors
CSE 5392 By Dr. Donggang Liu 13
Transmission media
• Wireless communication– Radio – Infrared – Optical media
• Multi-hop communication– Short distance wireless links
• Unreliable– Low bandwidth, low power
CSE 5392 By Dr. Donggang Liu 14
Power consumption
• The lifetime of a node strongly depends on the battery lifetime
• Sensing, communication, and data processing.– Sensing power: depends on applications– Communication: expensive
• Involves both data transmission and reception
• The active power + the start-up power consumption
– Data processing: not expensive• In-network processing is crucial to minimize power
consumption in a multi-hop sensor network.
CSE 5392 By Dr. Donggang Liu 15
Communication Architecture
CSE 5392 By Dr. Donggang Liu 16
Protocol Stack
CSE 5392 By Dr. Donggang Liu 17
Physical Layer
• Wireless radio signals– Frequency selection– Frequency generation– Signal detection – Modulation.
• Examples:– CC1000 chipset in Mica2
CSE 5392 By Dr. Donggang Liu 18
Data Link Layer
• Media access control– Provide fair and efficient access to the channel– It provide point-to-point link– Example: CC1000RadioIntM.nc
• Error Control– Simple error correction scheme– CRC check– Example: RadioCRCPacket.nc
• Energy aware
CSE 5392 By Dr. Donggang Liu 19
Network Layer
• Routing (infrastructureless network)– Ad hoc routing techniques (e.g., DSR) do not fit
• Power efficiency
• Data centric routing
• Data aggregation
• Example:– Flooding: each node receiving a packet repeats it by
broadcasting (simple flooding versus TTL-based)– Geographic forwarding: forward packets to the nodes close
to the destination node
• Energy aware
CSE 5392 By Dr. Donggang Liu 20
Transport Layer
• An open research issue
• This layer is especially needed when the system is planned to be accessed through Internet or other external networks.
CSE 5392 By Dr. Donggang Liu 21
Application Layer
• An open research issue
• Depends on applications:– Makes the hardware and software of the lower
layers transparent to the applications
CSE 5392 By Dr. Donggang Liu 22
A Simple Protocol Stack
CC1000RadioIntM.nc CC1000ControlM.nc
A simple send/receive application
send receive control
CSE 5392 By Dr. Donggang Liu 23
Active Research Area
• Routing
• Topology management
• Data management
• MAC protocols
• Target tracking, service discovery
• Monitoring and maintenance
• Security and privacy