An overview on Wireless Sensor Networks technology Prof. Romano Fantacci Dr. Francesco Chiti Dr. Daniele Tarchi GoodFood

1. MIDRA Consortium WP 7 – Ambient Intelligence An overview on Wireless Sensor Networks technology Prof. Romano Fantacci Dr. Francesco Chiti Dr. Daniele Tarchi GoodFood Project

2. Contents • WSN features • Characteristics • Aims • WSN implementation • Multihopping approach • Protocols characterization • Application layer • Transport layer • Network layer • LLC sub-layer • MAC sub-layer • Physical layer • References

3. Definition Task Mng Gateway Gateway 2G/3G N N N N N N N N Satellite N N N N N IPvx N • WSN features Wireless Sensor Network (WSN) is composed of a large number of sensor nodes (N) that are densely deployed either inside the investigated phenomenon or very close to it.

4. WSN Applications • WSN features • Military, Environmental, Health, Home, Space Exploration, Chemical Processing, Disaster Relief Sensor types • Seismic, Low sampling rate magnetic, Thermal, Visual, Infrared, Acoustic, Radar Sensor tasks • Temperature, Humidity, Lightning Condition, Pressure, Soil Makeup, Noise Levels • Vehicular, Movement, Presence or Absence of certain types of objects, Mechanical stress levels on attached Objects, current characteristics (Speed, Direction, Size) of an object

5. WSN features Multi-Hop WSN • Theorem (Stojmenovic, Xu Lin) • Let be the source and the gateway at distance d andthe needed transmitted power satisfies: • This is minimized if: • Otherwise, the overall requested energy can be minimized by choosing equally spaced n-1relay nodes such that n is the integer closer to:

6. Source relay relay Gateway • WSN features Multi-Hop WSN Communication paradigm

7. WSN GATEWAY 3 0 1 Dummy node 2 4 6 Sensor Node 5 • WSN features Multi-Hop WSN Flexibility: • Adaptability • Re-configurability • Robustness • Scalability • Energy-awareness • Power saving • Untethered • No nw planning • Random deployment • Self-organization • Re-configuration • Cooperative approach • Distributed procedures • Data processing

8. WSN implementation (HW & SW) Location Finding Mobilizer Transceiver Sensor ADC Processor Memory Power Unit • WSN node description Functional blocks Network Nodes Gateway

9. Protocol design • WSN features • Ad Hoc protocol are often unsuitable because: • Number of sensor nodes can be several of magnitude higher • Sensor nodes are densely deployed and are prone to failures • The topology of a sensor network changes very frequently due to node mobility and node failure • Sensor nodes are power, computational capacities and memory limited • May not have global ID like IP address • Need tight integration with sensing tasks • Specific cross-layer protocols design with an across layers information passing and functionalities adaptation to channel and load variations

10. Layers stack description Application Transport Task Management Plane Network Mobility Management Plane Power Management Plane Logical Link Control Medium Access Control Physical • Protocols characterization

11. Application layer Application Transport Network LLC MAC Physical • Protocols characterization • Sensor Management Protocol (SMP) • SMP allows the system administrators to interact with the sensors: • Moving the sensor nodes • Turning sensors on and off • Querying the WSN configuration and the status of nodes and re-configuring them if needed • Managing the authentication, key distribution and security in data communications • Time-synchronizing the nodes • Exchanging data related to the location finding algorithms • Introducing the rules related to data aggregation, attribute-based naming and clustering to the sensor nodes

12. Transport layer Application Transport Network LLC MAC Physical • Protocols characterization • The aims is to provide an end-to-end reliable communication by controlling the data flows • Avoiding duplicate or out-of-order packets • Error recovering • Resolving the network congestion in a proactive/reactive way since the goodput decreases drastically when network capacity is exceeded • Wireless TCP variants are not suitable for WSN as: • Different notion of end-to-end reliability • Huge buffering requirements • ACKing is energy draining

13. Network layer Application Transport Network LLC MAC Physical • Protocols characterization • This layer is in charge of discovering the best path between a couple of nodes (Sender and Destination), relaying on the following characteristics: • Sensor networks are mostly data centric • An ideal sensor network has attribute based addressing and location awareness • Data aggregation may be joined with a collaborative effort • Power efficiency is always a key factor

14. Network layer Application Transport Network LLC MAC Physical • Protocols characterization • Metrics considered to develop energy efficient routing algorithms: • Power Available (PA) at each node • Energy () needed to send a packet over a link • Resorting to these, there 4 possible approaches to choose the proper path: • Maximum PA Route (PAs summation) • Minimum Energy Route ( summation) • Minimum Hop Route (number of hops) • Maximum Minimum PA Route (minimum of maximum PA)

15. Application Transport Network • PROs • Simple implementation • No table updating • No neighbor nodes discovering • Scalability • CONs • Implosion and goodput decreasing • Duplicate packets • No available resource knowledge LLC MAC Physical • Protocols characterization Network layer • Flooding • Each node forwards the packets to all the neighbor nodes within its transmission range

16. Application Transport Network • PROs • Scalability • Adaptability • Modularity • Graceful performance degradation • No implosion • CONs • Long convergence transient time • Possible presence of loops • Packet loss if TTL expires • Signaling overhead LLC MAC Physical • Protocols characterization Network layer • Gossiping • Each node sends a packet only to one neighbor node chosen according to a suited criterion (random or metric based)

17. Network layer Application Transport Network LLC MAC Physical • Protocols characterization • Quality of Service oriented routing protocols • Routes based on QoS requirements without periodic table updating (no need for routing tables ) • Flexibile, robust and modular • One-to-one, many-to-one, one-to-many, and many-to-many communications • Types of Streams • Type 1: Time critical and loss sensitive • Type 2: time critical but not loss sensitive data • Type 3: loss sensitive data that is not time critical • Type 4: neither time critical nor loss sensitive

18. Logical Link Control sub-layer Application Transport Network LLC MAC Physical • Protocols characterization • To perform the error control of transmission data • Forward Error Correction (FEC) • Automatic Repeat reQuest (ARQ) • Hybrid ARQ (H-ARQ)

19. Medium Access Control sub-layer Application Transport Network LLC MAC Physical • Protocols characterization • Creation of the self-organizing network infrastructure, by means of establishing a communication links for data transfer among thousands of sensor nodes densely deployed • To fairly and efficiently share communication resources among sensor nodes. • Proposed MAC protocols: • SMACS and EA • Hybrid TDMA/FDMA • CSMA-based

20. Physical layer Application Transport Network LLC MAC Physical • Protocols characterization Bit-by-bit signal delivering and processing on a link-to-link basis • Modulation and detection schemes (simple and low power) • base band (UWB IEEE 802.15.3) • pass band (IEEE 802.11, IEEE 802.15.4) • Distribute and accurate synchronization protocols • post-facto • reference-broadcast synchronization • Power management by exploiting the sleeping mode

21. References • Heinzelman, W. R., Chandrakasan, A., Balkrishnan, H., “Energy-Efficient Communication Protocols for Wireless Microsensor Networks”, in Proc. IEEE Hawaii Int. Conf. on System Sciences, January 2000 • Heinzelman, W. R., “Application-specific Protocol Architectures for Wireless Networks”, PhD Thesis, Dept. of Electrical Engineering and Computer Science, MIT, June 2000. • Claire, Pottie, Agre, “Self-organizing Distributed Sensor Networks”, Proc. of International Symposium on low-power Electronic Design, 1997 • Hill, J., Szewczyk, R., Woo, A., Hollar, S., Culler, D., Pister, K., “System Architecture Directions for Networked Sensors”, in ASPLOS, November 2000 • Jiang, G., Cybenko, G., “A Simple Protocol for Infrastructure Monitoring and Management”, proc. of 2002 IEEE workshop on Information Assurance. • Iwata, A., Chiang, C., Pei, G., Gerla, M., Chen, T., “Scalable Routing Strategies for Ad-hoc Wireless Networks”, IEEE JSAC, August 1999 • E. Shih, S.-H. Cho, N. Ickes, R. Min, A. Sinha, A. Wang, and A. Chandrakasan, “Physical Layer Driven Protocol and Algorithm Design for Energy Efficient Wireless Sensor Networks”, in Proc. of ACM MobiCom ’01, Rome, Italy, Jul. 2001, pp. 272-286 • J. Elson and D. Estrin, “Time Synchronization for Wireless Sensor Networks,” in Proceedings of 15th IPDPS, Apr. 2001, pp. 1965 – 1970.

22. References • Sohrabi, K.; Gao, J.; Ailawadhi, V.; Pottie, G.J., “Protocols for self-organization of a wireless sensor network”, IEEE Pers. Comm., vol. 7, Oct. 2002, pp. 16-27 • E. Shih, S.-H. Cho, N. Ickes, R. Min, A. Sinha, A. Wang, and A. Chandrakasan, “Physical Layer Driven Protocol and Algorithm Design for Energy Efficient Wireless Sensor Networks”, in Proc. of ACM MobiCom ’01, Rome, Italy, Jul. 2001, pp. 272-286 • Rodoplu V., and Meng T.H., “Minimum Energy Mobile Wireless Network,” IEEE JSAC, vol. 17, no. 8, Aug. 1999, pp. 1333-44 • I. F. Akyldiz, W. Su, Y. Sankarasubramaniam, and E. Cayirci, “A survey on sensor networks”, IEEE Comm. Mag., Aug. 2002, pp. 102-114 • Intanagonwiwat, C., Govindan R., and Estrin D., “Directed Diffusion: A Scalable and Robust Communication Paradigm for Sensor Networks,” Proc. ACM MobiCom ’00, Boston, MA, 2000, pp.56-57. • Heinzelman W. R., Kulik J., and Balakrishnan H., “Adaptive Protocols for Information Dissemination in Wireless Sensor Networks,“ Proc. ACM MobiCom ’99, Seattle, Wa, 1999, pp 174-85. • Rodoplu V., and Meng T.H., “Minimum Energy Mobile Wireless Network,” IEEE JSAC, vol. 17, no. 8, Aug. 1999, pp. 1333-44 • Li L., and Halpern J.Y., “Minimum Energy Mobile Wireless Network Revisited,” ICC ’01, Helsinki, Finland June 2001

23. References • Birman K., “Bimodal Multicasting,” Cornell University, Department of Computer Science Technical Report TR-98-1665, May 1998 • Golding R.A., Long D.E., “The performance of weak-consistency replication protocols,” University of California at Santa Cruz, Computer Research Laboratory Technical Report UCSC-CRL-92-30, July 1992 • Renesse van R., Minsky Y., “A Gossip style failure detection service,” Proceedings of the IFIP International Conference on Distributed Systems Platform and Open Distributed Processing (Middleware ’98), The Lake District, England, September 1998 pp. 55-70 • Guo K., “An efficient gossip-style garbage collection scheme for scalable reliable multicast,” Cornell University, Department of Computer Science Technical Report TR-97-1656, December 3 1997. • Pittel B., “On spreading a rumor,” SIAM Journal on Applied Mathematics, 47(1987):213-223 • Heinzelmann W.r., Chandrakasan A., Balakrishnan H., “Energy-Efficient Communication Protocol for Wireless Microsensor Networks,” Massachussets Institute of Technology, Cambridge, MA 02139 • J. M. Rabaey et al., “PicoRadio Supports Ad Hoc Ultra-Low Power Wireless Networking,” IEEE Comp. Mag., 2000, pp. 42–48

24. References • S. Tilak, N. B. Abu-Ghazaleh and W. Heinzelman, “Infrastructure Tradeoffs for Sensor Networks” in Proc. of WSNA’02, September 2002, Atlanta, GA, USA • F. Stann and J. Heidemann, “RMST: Reliable Data Transport in Sensor Networks”, in Proc. of SNPA’03, May 2003, Anchorage, Alaska, USA • C. Y. Wan, A. T. Campbell and L. Krishnamurthy, “PSFQ: A Reliable Transport Protocol for Wireless Sensor Networks” in Proc. of WSNA’02, September 2002, Atlanta, GA , USA • C. C. Shen et.al., “Sensor Information Networking Architecture and Applications”, IEEE Personal Communications Magazine, pp. 52-59, August 2001 • K.A. Delin and Shannon P. Jackson, “The SensorWeb: A New Instrument Concept”, in Proc. of SPIE Symposium on Integrated Optics, San Jose, CA, January 2001 • K.A. Delin, S.P. Jackson, and R.R. Some, “SensorWebs,” NASA Tech Briefs, 23, pg. 80, 1999 • K.A.Delin and S.P. Jackson, “Sensor Web for in situ exploration of gaseous biosignatures”, in Proc. of IEEE Aerospace Conference 2000, vol. 7, pp. 465 - 472