1. CSE 5392By Dr. Donggang Liu1 CSE 5392 Sensor Network Security Introduction to Sensor Networks

2. CSE 5392By Dr. Donggang Liu2 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 synchronization 4. Energy management, robustness, etc.

3. CSE 5392By Dr. Donggang Liu3 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)

4. CSE 5392By Dr. Donggang Liu4 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

5. CSE 5392By Dr. Donggang Liu5 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

6. CSE 5392By Dr. Donggang Liu6 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

7. CSE 5392By Dr. Donggang Liu7 Features of Sensor Networks Fault tolerance Scalability Production costs Hardware constraints Sensor network topology Transmission media Power consumption

8. CSE 5392By Dr. Donggang Liu8 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

9. CSE 5392By Dr. Donggang Liu9 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.

10. CSE 5392By Dr. Donggang Liu10 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

11. CSE 5392By Dr. Donggang Liu11 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

12. CSE 5392By Dr. Donggang Liu12 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

13. CSE 5392By Dr. Donggang Liu13 Transmission media Wireless communication –Radio –Infrared –Optical media Multi-hop communication –Short distance wireless links Unreliable –Low bandwidth, low power

14. CSE 5392By Dr. Donggang Liu14 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.

15. CSE 5392By Dr. Donggang Liu15 Communication Architecture

16. CSE 5392By Dr. Donggang Liu16 Protocol Stack

17. CSE 5392By Dr. Donggang Liu17 Physical Layer Wireless radio signals –Frequency selection –Frequency generation –Signal detection –Modulation. Examples: –CC1000 chipset in Mica2

18. CSE 5392By Dr. Donggang Liu18 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

19. CSE 5392By Dr. Donggang Liu19 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

20. CSE 5392By Dr. Donggang Liu20 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.

21. CSE 5392By Dr. Donggang Liu21 Application Layer An open research issue Depends on applications: –Makes the hardware and software of the lower layers transparent to the applications

22. CSE 5392By Dr. Donggang Liu22 A Simple Protocol Stack CC1000RadioIntM.nc CC1000ControlM.nc A simple send/receive application sendreceivecontrol

23. CSE 5392By Dr. Donggang Liu23 Active Research Area Routing Topology management Data management MAC protocols Target tracking, service discovery Monitoring and maintenance Security and privacy