1. An Energy Efficient MAC Protocol for Wireless LANs Eun-Sun Jung Nitin H. Vaidya IEEE INFCOM 2002 Speaker ：王智敏 研二

2. Abstract Presenting an optimization of the power saving mechanism in the DCF Dynamically choose a suitable ATIM window size

3. Outline Introduction Power Saving Mechanism for DCF in IEEE 802.11 Related Work Proposed DPSM Scheme Performance Evaluation Conclusion

4. Introduction Conserving energy Routing Medium access protocol (MAC) Transport protocols Wireless interface Awake state Doze state Off state

5. Introduction This paper focus on the power saving mechanism proposed for DCF Beacon interval Synchronizing ATIM Window Goal Presents an adaptive mechanism to dynamically adjust the size of ATIM window

6. Power saving mechanism for DCF in IEEE 802.11 awake

7. Related Work [20]shows the significant impact on throughput and energy consumption different size of beacon interval and ATIM window [21]requires a node to enter the doze state if it overhear RTS/CTS for data transmission SPAN[18] elects a group of coordinators which are changed periodically

8. Related Work [22]proposes a communication protocol in wireless microsensor networks limited energy capacity and wireless channel bandwidth LEACH (Low-Energy Adaptive Clustering Hierarchy) minimize global energy consumption PAMAS (Power-aware routing in mobile ad hoc networks)[5], each node uses two separate channels for control packet and data packet transmissions

9. Proposed DSPM Scheme Key Features of DPSM DPSM Operation Rules for Dynamic ATIM windows Adjustment

10. Proposed DSPM Scheme ─Key Features of DPSM Dynamic adjustment of ATIM window Different ATIM window size Long dozing time (more energy saving) PSM Multi-packet A B other data ATIM data dozing ATIM Beacon interval DPSM one-packet A B other datadozing ATIM data dozing ATIM Beacon interval

11. DPSM Multi-packet A B other data ATIM data dozing ATIM Beacon interval Less 1600  s ATIM Awake Awake-to-doze Doze-to-awake

12. Proposed DSPM Scheme ─DPSM Operation Announcing one ATIM frame per destination Including the numbers of packet Sorted by the size of the ATIM window Increasing and decreasing ATIM windows size {ATIMmin………} level Backoff algorithm for ATIM frame

13. Proposed DSPM Scheme ─DPSM Operation Packet marking Retry limit for ATIM frame as 3 Re-buffered queue (2 beacon interval) Piggbacking of ATIM of ATIM window size Two queue ATIM windows size queue Re-buffered queue (ATIMmin)

14. Backoff Re-buffered

15. Rule for Dynamic ATIM Windows Adjustment ─ Increasing Based in the number of pending packets that could not be announced during the ATIM windows Based on overheard information At least two levels larger than that being used Receiving an ATIM frame after ATIM windows Receiving a marked packet

17. Rule for Dynamic ATIM Windows Adjustment ─ Decreasing Decreasing All pending packets have been transmitted No window increasing rule is satisfied ATIM window between 2 ~26 ms

18. Simulation model Ns-2 8,32 or 64 nodes Channel bit rate is 2Mbps Packet size is 512 bytes ATIM window between 2 ~50 ms ATIMmin = 2ms Transmit 、 Receive 、 Idle and Doze 1.65W 、 1.4W 、 1.15W 、 0.045W

19. Simulation model ─Fixed Network Load

20. Aggregation Throughput ─over all flows in the network(1/3)

21. Aggregation Throughput ─over all flows in the network(2/3)

22. Aggregation Throughput ─over all flows in the network(3/3)

23. Aggregation Throughput ─throughput per joule(1/3)

24. Aggregation Throughput ─throughput per joule(2/3)

25. Aggregation Throughput ─throughput per joule(3/3)

26. Simulation model ─Fixed Network Load

27. Dynamic Network Load Aggregation Throughput ─over all flows in the network(1/3)

28. Dynamic Network Load Aggregation Throughput ─over all flows in the network(2/3)

29. Dynamic Network Load Aggregation Throughput ─over all flows in the network(3/3)

30. Dynamic Network Load Aggregation Throughput ─throughput per joule(1/3)

31. Dynamic Network Load Aggregation Throughput ─throughput per joule(2/3)

32. Dynamic Network Load Aggregation Throughput ─throughput per joule(3/3)

33. Conclusion Adapting ATIM window size Dynamically Improving energy consumption without degrading throughput

34. Thank You !! kuko