Sensor Networks

1. Sensor Networks by K. Subrahmanya Sreshti (05IT6004) Under the Guidance of Prof. Shamik Sural School of Information Technology Indian Institute of Technology, Kharagpur.

2. Technical Terms • SINA – Software Information Network Architecture. • Beacons. • TinyOS – Tiny Micro-threading Operating System. • SPIN – Sensor Protocols for Information via Navigation. Presentation on Sensor Networks

3. Contents • Introduction • Overview of Architecture and Operating System • Energy Efficient methods • Localization • Routing • Applications (Some systems which make use of sensor networks) • Sensor Network simulators • Conclusion Presentation on Sensor Networks

4. Introduction • Definition: • Sensor networks are dense wireless networks of small, low-cost sensors, which collect and disseminate environmental data. • Used for monitoring and controlling of physical environments from remote locations with better accuracy. Presentation on Sensor Networks

5. Introduction (Cont…) • Earlier sensor networks… • Now, sensor networks… • Why distributed, wireless sensing??? • Closer placement. • Depends upon: • Dense Deployment. • Co-ordination among the nodes. Presentation on Sensor Networks

6. Features • Local Processing. • Wireless Communication. • Complete system on Chip. • Integrated Low-power communication. • Integrated Low-power transducers. Presentation on Sensor Networks

7. Focus Is On… • Energy and computational constraints. • Energy Efficiency. • Localization algorithms. • Routing. Presentation on Sensor Networks

8. 2. Architecture • Characteristics: • Small physical size and low power consumption. • Concurrency intensive operation. • Limited physical parallelism and controller hierarchy. • Diversity in design and usage. • Robust Operation. • Sensor Information Networking Architecture – A middle ware. • Issue queries and command tasks into. • Collects replies and results from. • Monitor changes. • Hierarchical Clustering. • Attribute-based naming. • Location Awareness. Presentation on Sensor Networks

9. 2. Architecture (Cont…) • Data sheets. • Sensor Query and Tasking Language (SQTL). • Interface between sensor application and SINA middleware. • getTemperature, turnON, isNeighbor, getPosition, tell, execute, etc. • Event handling: Receive, every, expire. • Software Execution Engine ( ALL, NEIGHBORS, etc ) Presentation on Sensor Networks

10. Information Gathering • Sampling Operation (Adaptive Probability Response). • Self-Orchestrated Operation. • Diffused Computation Operation. • Internetworking between a Mobile User and Stationary Network. • Tracking the mobile User. • Progressive footprint chaining. Presentation on Sensor Networks

11. 2. Architecture (Cont…) • Hardware Organization. • Processor and co-processor. • Provide interfaces to sensing devices (light, temperature, etc). • Designed to work in three different modes (idle, power down, power save). • Three leads available. • Power Characteristics. • Why an OS? • Requirement of an OS which can perform the tasks. • Effective usage of hardware. • Support concurrent-intensive operation. • Unused CPU cycles are spent in sleep mode. • Achieve robustness. Presentation on Sensor Networks

12. 2. Architecture (Cont…) • TinyOS design. • Event modeling. • A stack based threaded approach. • Two level scheduling. • Components. • Set of command handlers. • Set of event handlers. • An encapsulated fixed size frames. • Bundle of simple tasks. Presentation on Sensor Networks

13. Figure 1: http://citeseer.ist.psu.edu/382595.html Presentation on Sensor Networks

14. Presentation on Sensor Networks

15. 3. Energy Efficiency • Computing Subsystem. – microprocessor. • Communication subsystem. – radio. • Sensing subsystem – sensors and actuators. • Power Supply – consists of a battery. • Solution. • Develop methodologies which are energy aware. • Distribution of traffic. • Residual Energy Scan (eScan) – by Younggang Zaho. Presentation on Sensor Networks

16. 4. Localization • Nodes are in general deployed into an unplanned infrastructure (no priori knowledge). • Problem of estimating the spatial co-ordinates is referred to as Localization (generally done by trilateration). • Initial high-level nodes (beacons) broadcasts their address. (Proximity based Localization). • Multilateration (iterative process). Presentation on Sensor Networks

17. Trilateration/multilateration A B A A B C Presentation on Sensor Networks

18. 4. Localization (Cont…) • Fine – grained. • Timing. • Signal Strengths. • Signal Pattern Matching. • Pre-scanning takes place. A central system assigns a unique signature to each square in the location grid. • Coarse – grained. • Proximity based Localization. Nodes should adopt themselves to avoid to available reference points. • Connectivity metric=(tot. no. of signals received)/(tot. no. of signals sent). • Node’s position is calculated by centroid of all reference points. Presentation on Sensor Networks

19. Suggested Alg. For Beacons • Random • Max • Grid • Heap (Selective Turning off BEacons) Presentation on Sensor Networks

20. 5. Routing • Implosion • Ad-hoc protocols • Proactive – static: maintains a routing table. • Reactive – dynamic: establishes when required. • Negotiation based protocols • SPIN (meta-data) : uses ADV, REQ and DATA. • SPIN – PP (point-to-point) • SPIN – EC (energy conservative) • SPIN – BC (broadcast) • SPIN – RL Presentation on Sensor Networks

21. 5. Routing (Cont…) • Directed diffusion. • Attribute-value pairs are maintained. • Sink. • Interest cache. • Fields. • Timestamp. • Gradient – data rate. • Duration – lifetime. • Energy Aware Routing. • Destination initiative reactive protocol. • Multiple good optimal paths are maintained. Presentation on Sensor Networks

22. 6. Applications • Active Badge Location System. • Pin-point 3D-iD local positioning system. • Intelligence department. • Environmental monitoring. • Military purposes. • Gathering sensing information in inhospitable locations. Presentation on Sensor Networks

23. 7. Sensor Network Simulator • NS –2 ; written in c++ and oTCL. • GloMoSim (Global Mobile Information System Simulator); written in C and parsec. • SensorSim; Presentation on Sensor Networks

24. Challenges • Ad hoc deployment • Unattended Operation • Untethered (Limited Energy resource) • Dynamic Changes Ultimate Struggle • System Lifetime • System robustness Presentation on Sensor Networks

25. Conclusion • Promising applications • Evolving field • Scope for lots of research Presentation on Sensor Networks

26. References • http://wwwcsif.cs.ucdavis.edu/~bharathi/sensor/survey.pdf • http://ieeexplore.ieee.org/iel5/45/26953/01197877.pdf • http://ieeexplore.ieee.org/iel5/98/20430/00944004.pdf • http://citeseer.ist.psu.edu/382595.html • http://www.research.rutgers.edu/~mini/sensornetworks.html • http://www2.parc.com/spl/members/zhao/stanford-cs428/ • http://www.eng.auburn.edu/users/lim/sensit.html • http://geometry.stanford.edu/member/guibas/ • http://pdos.csail.mit.edu/span/ • http://www.tinyos.net/ • http://bit.csc.lsu.edu/news/faculty-candidate.html • http://www.janet.ucla.edu/WINS/ • http://www.cs.duke.edu/~alvy/courses/sensors/Papers.html Presentation on Sensor Networks

27. Thank You Presentation on Sensor Networks