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Presented by Jehn-Ruey Jiang Department of Computer Science and Information Engineering

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  1. A Hybrid Power-Saving Protocol by Dual-Channel andDual-Transmission-Rangefor IEEE 802.11-Based MANETs Presented by Jehn-Ruey Jiang Department of Computer Science and Information Engineering National Central University

  2. To Rest, to Go Far!!

  3. Outline • IEEE 802.11 MANETs • Power Saving Problem • Hybrid Power Saving Protocols • Simulation Results • Conclusion

  4. Outline • IEEE 802.11 MANETs • Power Saving Problem • Hybrid Power Saving Protocols • Simulation Results • Conclusion

  5. IEEE 802.11 Overview • Approved by IEEE in 1997 • Extensions approved in 1999 (High Rate) • Standard for Wireless Local Area Networks (WLAN)

  6. WLAN Market Source:wireless.industrial-networking.com

  7. IEEE 802.11 Family(1/3) • 802.11 (1997) • 2 Mbps in the 2.4 GHz band • 802.11b (1999) (WiFi, Wireless Fidelity) • 5.5 and 11 Mbps in the 2.4 GHz band • 802.11a (1999) (WiFi5) • 6 to 54 Mbps in the 5 GHz band • 802.11g (2001) • 54 Mbps in the 2.4 GHz band • 802.11n (2005) (MIMO) • 108 Mbps in the 2.4 and the 5 GHz bands

  8. IEEE 802.11n Access Point Source: http://www.d-cross.com/

  9. IEEE 802.11n Access Point NIC Source: http://www.d-cross.com/

  10. IEEE 802.11 Family(2/3) • 802.11c • support for 802.11 frames • 802.11d • new support for 802.11 frames • 802.11e • QoS enhancement in MAC • 802.11f • Inter Access Point Protocol • 802.11h • channel selection and power control

  11. IEEE 802.11 Family(3/3) • 802.11i • security enhancement in MAC • 802.11j • 5 GHz globalization

  12. Infrastructure vs. Ad-hoc Modes Infrastructure Network Wired Network AP AP AP Multi-hop Ad Hoc Network Ad-Hoc network Ad-Hoc network

  13. Ad Hoc Network (1/3) • A collection of wireless mobile hosts forming a temporary network without the aid of established infrastructure or centralized administration • by D. B. Johnson et al. • Also called MANET(Mobile Ad hoc Network) • by Internet Society IETF

  14. Ad Hoc Network (2/3) • Single-Hop • Each node is within each other’s transmission range • Fully connected • Multi-Hop • A node reaches another node via a chain of intermediate nodes • Networks may partition and/or merge

  15. Ad Hoc Network (3/3) • Application • Battlefields • Disaster Rescue • Spontaneous Meetings • Outdoor Activities

  16. Outline • IEEE 802.11 MANETs • Power Saving Problem • Hybrid Power Saving Protocols • Simulation Results • Conclusion

  17. Power Saving Problem • Battery is a limited resource for portable devices • Battery technology does not progress fast enough • Power saving becomes a critical issue in MANETs, in which devices are all supported by batteries

  18. Solutions to Power Saving Problem • PHY Layer: transmission power control • Huang (ICCCN’01), Ramanathan (INFOCOM’00) • MAC Layer: power mode management • Tseng (INFOCOM’02), Chiasserini (WCNC’00) • Network Layer: power-aware routing • Singh (ICMCN’98), Ryu (ICC’00)

  19. Transmission Power Control • Tuning transmission energy for higher channel reuse • Example: • A is sending to B (based on IEEE 802.11) • Can (C, D) and (E, F) join? No! Yes! B C D A E F

  20. Power Mode Management • Doze mode vs. Active mode • Example: • A is sending to B • Does C need to stay awake? No! It can turn off its radio to save energy! B But it should turn on its radio periodiclally for possible data comm. A C

  21. + – + – + – + – + – + – Power-Aware Routing • Routing in an ad hoc network with energy-saving (prolonging network lifetime) in mind • Example: N2 N1 SRC DEST Better!! N3 N4

  22. Our Focus • Among the three solutions: • PHY Layer: transmission power control • MAC Layer: power mode management • Network Layer: power-aware routing

  23. IEEE 802.11 PS Mode • An IEEE 802.11 Card is allowed to turn off its radio to be in the PS mode to save energy • PowerConsumption:(ORiNOCO IEEE 802.11b PC Gold Card) Vcc:5V, Speed:11Mbps

  24. MAC Layer Power-Saving Protocol • Two types of MAC layer PS protocol for IEEE 802.11-based MANETs • Synchronous (IEEE 802.11 PS Protocol) • Synchronous Beacon Intervals • ATIM (Ad hoc Traffic Indication Map) • Asynchronous • Asynchronous Beacon Intervals • MTIM (Multi-Hop Traffic Indication Map)

  25. BeaconFrame ACK IEEE 802.11 PS Protocol Target Beacon Transmission Time(TBTT) Beacon Interval Beacon Interval ATIM Window ATIM Window Active mode Power saving Mode Host A No ATIM means no data to send or to receive with each other ATIM Data Frame Power saving Mode ATIM Window ATIM Window Active mode Host B ACK Clock Synchronized by TSF

  26. IEEE 802.11 PS Protocol (cont.) • Single-hop environment • Advantages • More power efficiency • Low active ratio (duty cycle) • Drawbacks • Clock synchronization for multi-hop networks is costly and even impossible • Network partitioning • Not Scalable

  27. Clock Drift Example Max. clock drift for IEEE 802.11 TSF (200 DSSS nodes, 11Mbps, aBP=0.1s)

  28. D ╳ F Network Partition ╳ E ╳ ╳ Network-Partitioning Example The red ones do not know the existence of the blue ones, not to mention the time when they are awake. The blue ones do not know the existence of the red ones, not to mention the time when they are awake. C A B Host A ATIM window Host B Host C Host D Host E Host F

  29. Asynchronous PS Protocols (1/2) • Try to solve the network partitioning problem to achieve • Neighbor discovery • Wakeup prediction • Without synchronizing hosts’ clocks

  30. Asynchronous PS Protocols (2/2) • Three existent asynchronous PS protocols • Dominating-Awake-Interval • Periodical-Fully-Awake-Interval • Quorum-Based • References: • “Power-Saving Protocols for IEEE 802.11-BasedMulti-Hop Ad Hoc Networks,”Yu-Chee Tseng, Chih-Shun Hsu and Ten-Yueng HsiehInfoCom’2002 • “Quorum-based asynchronous power-saving protocols for IEEE 802.11 ad hoc networks,” Jehn-Ruey Jiang, Yu-Chee Tseng, Chih-Shun Hsu and Ten-Hwang Lai, ACM Journal on Mobile Networks and Applications, Feb. 2005.

  31. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 1 Beacon interval Numbering Beacon Intervals n consecutive beacon intervals are numbered as 0 to n-1 And they are organized as an n array

  32. Quorum Intervals (1/4) Intervals from one row and one column are called Quorum Intervals Example: Quorum intervals arenumbered by 2, 6, 8, 9, 10, 11, 14

  33. Quorum Intervals (2/4) Intervals from one row and one column are called Quorum Intervals Example: Quorum intervals arenumbered by 0, 1, 2, 3, 5, 9, 13

  34. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Quorum Intervals (3/4) Any two sets of quorum intervals havetwocommon members For example: The set of quorum intervals {0, 1, 2, 3, 5, 9, 13} and the set of quorum intervals {2, 6, 8, 9, 10, 11, 14} have two common members: 2 and 9

  35. Host D 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Host C 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Quorum Intervals (4/4) Host D 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Host C 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 2 overlapping quorum intervals Even when the beacon interval numbers are not aligned (they are rotated), there are always at least two overlapping quorum intervals

  36. Structure of Quorum Intervals

  37. D F E Networks Merge Properly C A B Host A ATIM window Host B Beacon window Host C Monitor window Host D Host E Host F

  38. QAPS: Quorum-based Asynchronous Power Saving Protocols • Advantages • Do not need synchronized clocks • Suitable for multi-hop MANETs • Asynchronous neighbor discovery and wakeup prediction • Drawbacks • Higher active ratio than the synchronous PS protocol • Not suitable for high host density environment

  39. Outline • IEEE 802.11 MANETs • Power Saving Problem • Hybrid Power Saving Protocols • Simulation Results • Conclusion

  40. HPS Overview (1/5) • A Hybrid PS protocol • Synchronous – IEEE 802.11 PS protocol • Asynchronous – QAPS • Taking advantages of two types of PS protocols • To reduce the active ratio • Suitable for multi-hop MANETs • Utilizing the concepts of dual-channel and dual-transmission-range • Forming clustering networks

  41. HPS Overview (2/5) • Dual transmission ranges Cluster head uses • Range RA for inter-cluster transmission • Range RB for intra-cluster transmission F RA E RB E, F: cluster heads

  42. HPS Overview (3/5) • Dual channels Two non-interfering comm. channels are used • Channel A for inter-cluster transmission • Channel B for Intra-cluster transmission H Channel A G RA Channel B RB E, F: cluster heads

  43. HPS Overview (4/5) • Dual transmission ranges • Practical for IEEE 802.11 Standard • More power efficiency • Dual channels • Practical for IEEE 802.11 Standard • Non-interfering channels (such as 1, 6, 11) • Inter-cluster and Intra-cluster comm. can take place simultaneously

  44. HPS Overview (5/5) • Two types of beacon frames • Intra-cluster beacon • Send in channel B with transmission range RB • For cluster forming • For clock synchronization • Inter-cluster beacon • Send in channel A with transmission range RA • For neighboring cluster heads discovery • For wakeup prediction

  45. Structure of Beacon Intervals quorum Interval non-quorum Interval Cluster Head B M B M B’ M’ Active period Active period in channel B Active period in channel A non-quorum Interval quorum Interval Cluster members B’ M’ Active period in channel B B M :Beacon window and MTIM window in channel A B’ M’ :Beacon window and MTIM window in channel B :Monitor mode in channel A :PS mode

  46. State Transition A host enters the network initially Receive no intra-cluster beacon in channel B over ( q+1 beacon intervals + a random backoff time) Listening State Receive an intra-cluster beacon in channel B during q+1 beacon intervals Receive no intra-cluster beacon in channel B from cluster head over (q+1 beacon intervals + a random backoff time) Broadcast intra-cluster beacon every non-quorum interval Cluster Head State Cluster Member State Receive an intra-cluster beacon in channel B from the cluster head Exeunt mechanism is invoked

  47. The States (1/3) • Listening State • Listen in channel B for intra-cluster beacons for a period of (q+1 beacon intervals plus a random back-off time) 0-15 time slots with each time slot occupying 20 μs

  48. The States (2/3) • Cluster Head state • Running async PS protocolfor inter-cluster comm. • Running sync PS protocolfor inter-cluster comm.

  49. The States (3/3) • Cluster Member State • Synchronizing its clock with the cluster head’s • Running sync PS protocol • Adopting cluster head’s quorum information

  50. Cluster Forming (1/2) 100 hosts 33 cluster heads 67 cluster members RB