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A Survey on Sensor Networks

A Survey on Sensor Networks. Ian F. Akyildiz, Weillian Su, Yogesh Sankarasubramaniam, Erdal Cayirci. IEEE Communications Magazine, August 2002. Presented by Alexandra Czarlinska. Goals and Structure of this Paper. Analysis and Conclusions. Survey Communication Protocols for the 5 Layers.

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A Survey on Sensor Networks

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  1. A Survey on Sensor Networks Ian F. Akyildiz, Weillian Su, Yogesh Sankarasubramaniam, Erdal Cayirci IEEE Communications Magazine, August 2002 Presented by Alexandra Czarlinska

  2. Goals and Structure of this Paper Analysis and Conclusions Survey Communication Protocols for the 5 Layers Communication in Sensor Networks Introduction Special constraints of Sensor Networks Communication Topology Do these protocols work for Sensors? Encourage new research

  3. area A Cluster-Head or Aggregator Task Manager Node Density of nodes μ(R) = N πR2/A N = # of nodes in area A R is radio range Communication Topology Multi-hop wireless Sink / Base Station Internet or Satellite Self-organizing, non-homogenous Sensor Network End User

  4. UC- Berkeley mote Tiny sensor node with 7 sensing devices ; Photoresistor, Temperature, Barometric pressure, Barometric Pressure and Temperature, Humidity, Thermopile and Thermistor

  5. Location Finder Mobilizer Actuator Processor Sensor TX/RX ADC Storage Power Generator Power Unit Inside a Sensor Node

  6. Fault Tolerance Scalability Handle high density of nodes Handle loss of nodes Power Costs Limited Tx, computation, and lifetime Security ? Nodes die, make them low cost Confidentiality, Authentication etc Hardware Limitations Transmission Media Nodes are tiny wireless: RF, optical, infrared Changing Topology Nodes moving, new nodes, loss of nodes Survive and maintain communication Hostile Environment Special Constraints for Communication in Sensor Networks

  7. Protocol Stack and Sensor Network Management 5. Application Layer 4. Transport Layer Sensor Network Manage-ment 3. Network Layer Power Moving Collaboration 2. Data Link Layer 1. Layer Physical

  8. source freq 915 MHz? encryption ??? Transmit 0 1 1 0 1 0 1 . . . modulation d distance Sink Power to transmit ≈dn where 2 ≤ n ≤ 4 High antenna Low-lying antenna 1. Physical Layer Responsible for frequency selection, modulation and data Encryption. The big issue here is Power!

  9. Have/Know 1. Physical Layer • Binary Modulation needs less energy than M-ary modulation • More research on smaller hardware that uses less power (battery!) • Protocols that exploit node density and multi-hop redundancy • Direct Sequence Spread Spectrum is low power (transmission and security) • Ultra wideband (UWB) uses low power, does well under multi-path and has simple Tx/Rx Need

  10. Cellular MAC Bluetooth and MANET slave wireless Master wired Base Base 2. Data Link Layer Responsible for multiplexing of data streams, Medium Access control (MAC) and Error Control Problem: MAC ensures QoS and Bandwidth, not Power conservation, central base Problem: MAC ensures QoS under mobility. Not enough nodes, Tx power needed is too much, central base

  11. 2. Data Link Layer

  12. Have/Know 3. Network Layer Routes data supplied by the Transport Layer Also have: Pegasis, GEAR

  13. Have/Know Need 3. Network Layer • allow higher topology changes • Allow higher scalability

  14. 4 -Max Min Route along which the min PA is larger than the min PA of other routes 3. Network LayerPower Efficiency Routing 1- Max Power Available (PA) route, 2- Min Energy (ME) route, 3- Min Hop (MH) route and 4 - Max Min PA route 1- Max Power Available route A P = 1 P = 2 P = 3 Total P = 6 P = 2 P = 4 B P = 2

  15. Have/Know 4. Transport Layer Helps to maintain the flow of data if the Application Layer requires it. Needed if End-User accesses the Sensor Network through the Internet • Current TCP: • has a window mechanism that may not suit Sensor Networks • uses end-to-end Global Addressing (nodes may have Attribute-based or Location-based addressing) • TCP and UDP not based on power conservation and scalability

  16. TCP Need Internet UDP Sink UDP Task Manager Node End User 4. Transport Layer More research is needed to see if we need new protocols and what they might be. Suggestion by authors: TCP Splitting: TCP on one side, modified UDP on the other

  17. Sink Internet Task Manager Node End User 5. Application Layer Makes the hardware and software of the lower layers transparent to the Task Manager Node (and End-User)

  18. 5. Application Layer SMP TADAP SQDDP Task Assignment and Data Advertisement Protocols Sensor Query and Data Dissemination Protocol Sensor Management Protocol Rules for Data Aggregation, Time sync. Moving, turning nodes on/off Issue queries, collect replies Allows for Attribute-based and Location-based addressing Interest Dissemination from: - user to nodes - nodes to user

  19. Need 5. Application Layer Attribute-Based Addressing: The locations of nodes that sense temperature higher than 70 degrees Location-Based Addressing: What are the temperatures read by sensors in region A Data Centric Routing (not Address Based Routing): In general, more research is needed in all the areas mentioned

  20. Strengths and Contributions “A Survey on Sensor Networks” Great overview of what exists, why it’s good or not good for Sensor Networks Gives a table of on-going Sensor Network research projects • Identifies and motivates new areas of research that are needed Identifies certain general “design principles”

  21. Analysis: Weaker side • Does not mention security enough (should be designed right into the system, not after) • Does not mention Asymmetric Links • Does not mention Distributed Protocols sufficiently (could have no Base Station)

  22. Keep in Mind • Paper assumes that nodes do not have much energy but there is new research in: • solar cells, temperature gradients, vibrations, RF Transfer, Micro Heat Engines (using MEMS) • Assumes high density of cheap nodes vs. a few high quality nodes (keep in mind NASA) • Does not always assume the most GeneralTopology (ie: there could be no Base Station, there could be multiple sensing devices on one node etc)

  23. References • I. F. Akyildiz, W. Su, Y. Sankarasubramaniam, E. Cyirci, “ A survey on Sensor Networks”, Computer Networks, 38(4):393-422, March 2002 • http://www.greatduckisland.net • Chee-Yong Chong, S. P. Kumar, “Sensor networks: evolution, opportunities, and challenges”, Proceedings of IEEE, pp 1247-1256, August 2003

  24. Appendix Additional slides with more detail

  25. Fault Tolerance rk(t) = e – λk t Density of nodes μ(R) = N πR2/A λk is failure rate of node k N = number of nodes in area A t is time period R is radio range Sensor Network Communication Architecture area A

  26. Yogesh Sankarasu- bramaniam • Erdal • Cayirci Ian F. Akyildiz Weilian Su Authors of this Survey Georgia Institute of Technology School of Electrical and Computer Engineering Prof: wireless and satellite networks, next-gen Internet Phd: Timing recovery, ad hoc routing and Sensor Networks Phd: Sensor Networks and next-generation wireless Sensor Networks, mobile comm., tactical and military

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