1. Geography-informed Energy Conservation for Ad Hoc Routing Ya Xu, John Heidemann, Deborah Estrin ISI & UCLA Presented by: Cristian Borcea

2. Motivation reduce the energy consumption in ad hoc wireless networks increase the network lifetime

3. Solution identifies equivalent nodes for routing based on location information turns off unnecessary nodes

4. Assumptions dense node deployment many nodes can hear each other each node knows its location GPS... but better other methods

5. Energy Model listen:receive:transmit energy consumption 1:1.05:1.4 or 1:1.2:1.7 recall from last week listen:receive:transmit times are 1:3:40 duty cycle > 22% ==> more than 50% of energy spent in listening energy dissipation in idle state cannot be ignored

6. Effects of turning radio off in the idle state

7. Determining Node Equivalence the physical space is divided into equal size squares based on nominal radio range any two nodes in adjacent squares can communicate with each other the nodes within a square are equivalent

8. Geographical Adaptive Fidelity ( GAF ) Routing nodes in the same grid coordinate each other who will sleep and for how long runs over any ad hoc routing protocol load balancing energy usage all nodes remain up for us long as possible

9. GAF state transitions

10. Node Ranking node(active) > node(discovery) enat1>enat2 ==> node(enat1)> node(enat2) enat = estimated node active time node ids break the ties

11. Adapting to Mobility each node estimates the time when it expects the leave the grid: engt includes this estimation in the discovery message other nodes sleep for min(enat, engt) GAF-ma ( mobility adaptation ), GAF-b ( basic scheme )

12. Simulation ns2 + cmu's extension for 802.11 AODV vs GAF/AODV DSR vs GAF/DSR 50 transit nodes ( "routers" ) 10 traffic nodes ( sources & sinks ) Traffic: CBR Nominal radio range: 250

13. Energy model - values used in simulation WaveLAN (pre-802.11, 1995) 2Mb/s listen:receive:transmit 1:1.2:1.6W 0.025 when sleeping 802.11 wireless LAN 0.75:1.5:1.9W 802.11 cards 0.83:1:1.4W

14. Network Lifetime

15. GAF energy savings mean energy consumption per node (E0-Et)/(n*t) E0 initial total energy for n nodes Et total energy after time t results: GAF+AODV is 40% better than AODV for both GAF-b, GAF-ma

16. GAF-b vs GAF-ma

17. Data Delivery Ratio

18. Average Delay

19. Network lifetime: GAF vs AODV

20. Network Lifetime vs Node Density

21. Conclusions GAF increases the network lifetime does not decrease the performance substantially