1. Data Dissemination in Sensor Networks Challenges and Solutions by Sovrin Tolia

2. Presentation Outline Overview of Sensor Networks Directed Diffusion, A Scalable and Robust Communication Paradigm for Sensor Networks SPIN, Adaptive Protocols for Information Dissemination in Wireless Sensor Networks

3. Research Efforts Directed Diffusion USC/ISI Institute Deborah Estrin, Ramesh Govindan et al SPIN Protocols MIT Balakrishnan, Joanna Kulik et al

4. Challenges in Sensor Networks Sheer Numbers Unattended deployment Device failures Frequent Change Heterogenity of Tasks

5. Sensor Nodes Capability of Sensor Nodes Distributed Microsensing Sensor Networks are task specific Autonomous Operation

6. Sensor Network Applications Monitoring Remote Geographic Locations and terrains Toxic Urban Locations Less Accessible environments like large Industrial Plants and Aircraft Interiors

7. Directed Diffusion Motivated by Scalability, Energy Efficiency and and robustness Data Centric Application Aware Energy Efficient Remote Surveillance Sensor Network

8. Directed Diffusion Naming

9. Directed Diffusion Interests and Gradients Sink Nodes Periodic Broadcasts Interest Cache in every node (distinct interests) Two Way Gradient established Generalized Interest Propagation means

10. Directed Diffusion Data Propagation location satisfied, finds Interest Match from cache computes the highest data rate in gradients present in the interest cache Intermediate Node base their decision based on Data cache “Downconversion”

11. Directed Diffusion Reinforcement Data Driven Rules for deciding which node(s) to reinforce Explicitly send a high data rate Interest message What do the neighboring nodes do Extreme Reactivity and Negative Reinforcements

12. Directed Diffusion Explained

13. In Essence No mention of target detection algos The usage is not restricted to interests- gradients-drawing data. All Communication uses interests to specify named data Neighbor-Neighbor (Not End-to-End) No routers, governed by task specificity No Need for globally unique identifiers

14. Is It Routing ? Kind of Reactive, Routes on Demand No Attempt to find one loop free route Constrained Flooding is used Message Cache is used to avoid loops They did carry out some preliminary results

15. Future Research here Target Detection Algorithm Simulate Congestion in the network Experiment the non-aggressive reinforcement strategy and less conservative negative reinforcements Sensor Networks are at a stage where Internet was three decades ago

16. SPIN, Sensor Protocols for Information via Negotiation Overcomes Implosion, Overlap and Resource Blindness in conventional approaches Advocates Negotiation and Resource- adaptation

17. SPIN Naming Using Meta Data SPIN Messages ADV,REQ,DATA Resource Management Implementation 3-stage handshake Participation only when it can complete all the three stages

18. SPIN Working

19. SPIN Architecture

20. Performance Compared against flooding, gossiping and ideal protocol Metric is amount of data disseminated over time and energy consumed SPIN-1 higher throughput than gossip but same as flooding, less energy usage SPIN-2 ideal amount of data per unit energy

21. Food for Thought If Ad-hoc networks are not yet a reality, can we ever expect Sensor Networks to be deployed Are they really required ? ANY QUESTIONS