A Survey on Sensor Networks

1. A Survey on Sensor Networks Lan F.Akyildiz,Weilian Su, Erdal Cayirci ,and Yogesh sankarasubramaniam IEEE Communications Magazine 2002 Speaker:earl

2. Outline • Introduction • Communication architecture • Protocol stack • Conclusion

3. Introduction • Sensor Networks…low-cost, rapid deployment, self-organizing, and fault tolerance • Application areas: heath, military, and home • Large number of sensor nodes that are densely deployed • Nodes use their processing abilities to locally carry out simple computations and transmit the required and partially processed data

4. Application areas - heath

5. Application areas - military Compress data to reduce storage and communication bandwidth!

6. Application areas Inactive Sensor

7. Application areas

8. Application areas Active Sensor

9. Introduction • Ad hoc networks are not suitable for the sensor networks because of their unique features and application requirement • The sensor network may have a much larger number of nodes • Transmission power and radio range • Topology changes • Mobility rate • Power conservation

10. Communication Architecture Internet and Satellite Sink C D A E B Task manager node Sensor nodes Sensor field User

11. Design Factors • Fault Tolerance • the ability to sustain sensor network functionalities without any interruption due to sensor node failures • Scalability • the density of sensor nodes can range from few sensor nodes to few hundred sensor nodes in a region • Production Costs • the cost of sensor node should be much less than US$1 in order for the sensor network to be feasible • Environment • can work in different environments

12. Location finding system Mobilizer Sensing Unit Processing Unit Transceiver Processor Sensor ADC Storage Power Unit Power generator Design Factors • Hardware Constraints

13. Design Factors • Sensor Network Topology • Predeployment and deployment phase • Post-deployment phase • Redeployment of additional nodes phase • Transmission Media • links between nodes can be formed by radio,infrared, or optical media • Power Consumption • battery lifetime • design of power-aware protocols and algorithms

14. Task management plane Mobility management plane Application layer Transport layer Power management plane Network layer Data link layer Physical layer Protocol Stack

15. The Data Link Layer • Multiplexing of data streams • Data frame detection • Medium access and error control • Ensures reliable point-to-point and point-to-multipoint connections in a communication network

16. The Data Link Layer - Medium Access Control • Goals • share communication resources between sensor nodes fairly and efficiently

17. The Data Link Layer -Some of the proposed MAC protocols

18. The Data Link Layer • Power saving modes of operation • Turning the transceiver off during idling may not always be efficient due to energy spent in turning it back on each time • Error control • Two modes of error control: • Forward Error Correction(FEC) • decoding complexities • Automatic Repeat Request (ARQ) • additional retransmission energy cost and overhead

19. The Data Link Layer-Research issues • MAC for mobile sensor networks • Determination of lower bounds on the energy required for sensor network self-organization • Error control coding schemes • Power-saving modes of operation

20. Sink α 3=2 α 1=1 E (PA=1) α 4=2 A (PA=2) α 2=1 D (PA=3) α 6=2 α B (PA=2) 5=2 α 7=1 α 8=2 α10=2 F (PA=4) α 9=2 T C (PA=2) Network Layer Task: energy efficient routes Route 1: Sink-A-B-T, total PA=4, total α = 3 Route 2: Sink-A-B-C-T, total PA=6, total α = 6 Route 3: Sink-D-T, total PA=3, total α = 4 Route 4: Sink-E-F-T, total PA=5, total α = 6 PA: available power α:: energy required • Approaches: • Minimum PA route: route 4 • Minimum Energy (ME) route: route 1 • Minimum hop (MH) route: route 3 • Maximum minimum PA node route: route 3

21. C B A E D F G Sink Data Aggregation, data fusion Network Layer

22. Network Layer -Routing techniques • Floodingeach node receiving a data or management packet repeats it by broadcasting • Deficiencies • Implosion • Overlap • Gossipingsend the incoming packets to a randomly selected neighbor • Deficiency: takes a long time to propagate the message to all sensor nodes

23. ADV REQ DATA Step 1 Step 2 Step 3 ADV REQ DATA Step 4 Step 5 Step 6 Sensor Protocols for Information via Negotiation (SPIN) Network Layer

24. Network Layer • Sequential Assignment Routing (SAR) • Creates multiple trees where the root of each tree is a one-hop neighbor from the sink • Low-Energy Adaptive Clustering Hierarchy (LEACH) • Forms clusters to minimize energy dissipation • Directed diffusion • Sets up gradients for data to flow from source to sink during interest dissemination

25. BS Base station Sensor node Cluster head Cluster Network Layer • LEACH and Directed diffusion LEACH Directed diffusion

26. Conclusion • Sensor network is a new Research issue