Hierarchical Power Management in DTN with

Traffic-Aware Optimization

Hyewon Jun, etcACM SIGCOMM , 2006

Start Point …

Contacts discovered by two radios

Start Point…

Question Left

In DTN, if rely only on the low power radio to discover contacts…?

What if not?

This paper is targeting …

Hierarchical power management scheme

Traffic-aware Optimization

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

Continuous Aware Mechanism (CAM)High power radio always stays awake

to search for other nodes

Power Saving Mechanism(PSM)

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

Generalized Power Saving Mechanism (GPSM)

Power Management Schemes

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 …

Wake-Up Interval Estimation for PSM

Wake-Up Interval Estimation for SPSM

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 Sij of wake-up interval pairs that prov

ide enough bandwidth to consume the expected traffic load on the link (i; j) ;

Third, we find the pair of wake-up intervals (whij ; wlij) in Sij that will consume the least amount of energy;

Finally, choose the minimum wake-up intervals whi and wli among whij and wlij, respectively.

Performance Evaluation

Main Goal Analytical model accurately predicts contact

discovery

Wake-up mechanisms save significant energy

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

Contact Discovery

Traffic-Aware Power Management

Traffic-Aware Power Management

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 …

Summary

Present a hierarchical power management in DTNs

Traffic-aware optimization