1. TTDD: A Two-tier Data Dissemination Model for Large- scale Wireless Sensor Networks Haiyun Luo, Fan Ye, Jerry Cheng, Songwu Lu, Lixia Zhang (UCLA) Mobicom 2002 Bao-Hua Yang

2. Outline Introduction Two-tier data dissemination Performance evaluation Conclusion

3. Introduction

4. Stimulus Sink Assumption: Stimulus/sink: mobile, multiple Sensor node: stationary, with GPS

5. Introduction --- Basic idea Stimulus Sink Protocol Architecture 1.Grid construction 2.Two-Tier query and data forwarding 3.Grid maintenance α

6. Two-Tier data dissemination --- Grid construction source

7. Two-Tier data dissemination --- Grid construction α  data announcement will stop at a node that is closer to Lp than all its neighbors  Source send “ data announcement ” using greedy geographical forwarding Source location, Lp, Grid lifetime Dissemination node

8. Two-Tier data dissemination --- Grid construction α  Data announcement  L P  Upstream dissemination node

9. Two-Tier data dissemination --- Grid construction α

10. α

11. Two-Tier data dissemination --- Two-Tier query and data forwarding α

12. Primary Agent Immediate dissemination node

13. Two-Tier data dissemination --- Two-Tier query and data forwarding α

14. α

15. α

16. α

18. PA Immediate agent

19. Two-Tier data dissemination --- Two-Tier query and data forwarding PA IA

20. Two-Tier data dissemination --- Grid maintenance Two way to maintain the grid “ Grid lifetime ” in data announcement Dissemination node fails “ upstream information duplication ” mechanism

21. Two-Tier data dissemination --- Grid maintenance α

22. α

23. Performance Evaluation Simulator: ns-2 Parameter: Sink: 4 Source: 4 Sensor node: 200 Sensing range: 2000*2000 m 2 Simulation time: 200 second Cell size: 600 meters

24. Performance Evaluation

30. Conclusion TTDD: two-tier data dissemination Model Construct & maintain a grid structure with low overhead Can effectively deliver data from multiple sources to multiple mobile sinks