1. Hierarchical Power Management in DTN with Traffic-Aware Optimization Hyewon Jun, etc ACM SIGCOMM, 2006

2. Start Point … Contacts discovered by two radios

3. Start Point…

4. Question Left In DTN, if rely only on the low power radio to discover contacts…? What if not?

5. This paper is targeting … Hierarchical power management scheme Traffic-aware Optimization

6. DTN Radio Discovery Power management modes  Search: wake up periodically to discover a contact (wake-up interval)  Contact: stay awake to exchange messages  Dormant: remain asleep

7. Continuous Aware Mechanism (CAM) High power radio always stays awake to search for other nodes

8. Power Saving Mechanism(PSM)

9. Short-range-radio-dependent Power Saving Mechanism (SPSM)

10. Generalized Power Saving Mechanism (GPSM)

11. Power Management Schemes

12. Traffic-Aware Wake-up Interval Estimation Problem Statement  For each node, find the wake-up intervals that leads to discovering enough contacts to deliver the traffic load while minimizing energy consumption. Problem Formulation  Statistical contacts information  Traffic load ……

13. Wake-Up Interval Estimation for PSM

14. Wake-Up Interval Estimation for SPSM

15. Wake-Up Interval Estimation for GPSM First, estimate the expected bandwidth on the link (i; j) for each pair of wake-up intervals(wh;wl) in a given set of discrete wake-up interval pairs: Secondly, find a set S ij of wake-up interval pairs that provide enough bandwidth to consume the expected traffic load on the link (i; j) ; Third, we find the pair of wake-up intervals (wh ij ; wl ij ) in S ij that will consume the least amount of energy; Finally, choose the minimum wake-up intervals wh i and wl i among wh ij and wl ij, respectively.

16. Performance Evaluation Main Goal  Analytical model accurately predicts contact discovery  Wake-up mechanisms save significant energy

17. Performance Evaluation Simulation Setup  RWP  MF 12 stationary nodes (grid) and 8 mobile nodes (ferries) Ferries visit each node in order and repeat the route Metrics  Normalized energy consumption  Delivery ratio  Contact discovery ratio

18. Contact Discovery

19. Traffic-Aware Power Management

21. From the simulation… Traffic-aware optimization save considerable energy. Performance depends on mobility model: PSM vs SPSM. PSM with traffic-aware optimization achieves similar performance to GPSM, which indicates …

22. Summary Present a hierarchical power management in DTNs Traffic-aware optimization