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  • 1. GARUDA: Achieving Effective Reliability for Downstream Communication in Wireless Sensor Networks Seung-Jong Park, Member, IEEE, Ramanuja Vedantham, Member, IEEE, Raghupathy Sivakumar, Senior Member, IEEE, and Ian F. Akyildiz, Fellow, IEEE Report : Hsiung Chun Kuei IEEE TRANSACTIONS ON MOBILE COMPUTING, VOL. 7, NO. 2, FEBRUARY 2008
  • 2.
    • Data delivery can be critical
    • Guaranteed sink-to-sensors
    • Reliable downstream data
    Abstract http://wshlab2.ee.kuas.edu.tw
  • 3. Outline http://wshlab2.ee.kuas.edu.tw
  • 4. Introduction
    • Energy-aware protocols isn’t enough
      • Wireless Channel Errors
      • Congestion and Contention
      • Broadcast Storm
    http://wshlab2.ee.kuas.edu.tw
  • 5.
    • Delivered reliably
      • Control code
      • Query-data
      • Response result about sensor match data
    • Cornerstones of design
      • Reliable short-message.
      • V irtual infrastructure – core
      • Two-stage negative acknowledgment (NACK)
    Introduction http://wshlab2.ee.kuas.edu.tw
  • 6.
    • Assumptions
      • Downstream reliability
      • Communication and node failures
      • 100 % reliable message delivery
      • Message size less then one packet
      • Network model is static
    Framework http://wshlab2.ee.kuas.edu.tw
  • 7.
    • Single-/First-Packet Delivery
      • Benefits
        • Robust fading effects and collision.
        • Implicit NACK fit in short package.
        • Result in low energy.
    Framework http://wshlab2.ee.kuas.edu.tw
  • 8. Framework
      • Wait for first package(WFP) Pulse Transmission
    http://wshlab2.ee.kuas.edu.tw CS: carrier sensin
  • 9.
    • Loss Recovery Servers: Core
      • Goal
        • Minimize the retransmission overheads.
        • Constructed in a manage dynamic topology
      • Rationale of Core
        • MDS(Minimum Domination Set)
        • MSC(Minimum Set Cover)
    Design Element http://wshlab2.ee.kuas.edu.tw
  • 10. Framework
      • Instantaneous Core Construction
        • Sink
          • band-ID(bId) = 0
        • In 3i bands
          • Radom wait, and no invite message from the same band. It will be candidate.
          • Maintain upstream core’s information
        • In 3i+1
          • S 0 is S 1 ’s core ,when the new S 0 ’ core invite again, S 1 will trade off each other by delay time.
        • In 3i+2
          • When time out, the node will sends an anycast “core solicitation message” to 3(i+1) nodes. And then respond after a random waiting delay.
          • Boundary condition : not invite form core. Such condition can be detected.
    http://wshlab2.ee.kuas.edu.tw
  • 11. Framework
      • Loss Recovery for Core Nodes
        • Upstream core nodes
        • Downstream core nodes
          • A-map:myBM (successfully received packet),totBM(received and requested packets)
          • If A-map is from a valid source. Updating to totBM.
          • Send request , and set expire time. If receive the feedback to update to myBM
          • If no response from upstream core, requiring to default upstream core.
        • Intermediate noncore nodes
          • Set the vFlag to NULL when identifier is equal 3
    http://wshlab2.ee.kuas.edu.tw
  • 12. Framework
      • Loss Recovery for Noncore Nodes
        • Snoops all (re)transmissions from its core node.
        • After Period core presence timer, sends an explicit request to core node that response with A-map
    http://wshlab2.ee.kuas.edu.tw
  • 13. Performance evaluation
    • Evaluation of Single-Packet Delivery
    http://wshlab2.ee.kuas.edu.tw  
  • 14. Performance evaluation
    • Evaluation of Multiple-Packet Delivery
    http://wshlab2.ee.kuas.edu.tw (100 * 3.14 * 67 * 67) / (650 * 650) = 3.33620355 (800 * 3.14 * 67 * 67) / (650 * 650) = 26.6896284
  • 15. Performance evaluation
    • Microscopic Analysis
      • Optimality of the core
      • A-map overhead
      • Number of recovery events
      • Effect of random wireless errors
    http://wshlab2.ee.kuas.edu.tw
  • 16. Performance evaluation
    • Evaluation of Variants
      • Reliable Delivery within a Subregion
    http://wshlab2.ee.kuas.edu.tw
  • 17. Performance evaluation
      • Minimal Set of Sensors
    http://wshlab2.ee.kuas.edu.tw
  • 18. Conclusions
    • Future work
      • With mobility and in the presence of multiple sinks.
    • We can do ..
      • Take care of core ’s energy.
        • By reelection
      • Expand into multimedia
        • Addition to multi processes.
        • How many duplicate does the environment have?
    http://wshlab2.ee.kuas.edu.tw
  • 19. Q & A Thank for your attention
  • 20. Framework –D?
    • Two-Phase Loss Recovery
      • A-Map(Availability Map)
      • Function
        • Loss detection
        • Loss recovery
    http://wshlab2.ee.kuas.edu.tw
  • 21. Performance evaluation
    • Simulation Environment
      • 網路地形
        • 100 node,650mx650m,randomly deployed
        • Sink in center
        • Range 67m
        • 1Mbps
        • Message = 100 packets and 25 packets/per second (except for the single-packet-delivery part)
        • 1 packet = 1Kbyte
      • 協定參數
        • MAC protocol : CSMA/CA
        • Routing : flooding
        • Simple : 20 randomly topologies
        • So 95% confidence intervals
        • Error model : 5% fixed packet loss rate
    http://wshlab2.ee.kuas.edu.tw
  • 22. Other reliability semantics
    • Reliable Delivery within a Subregion
        • Without loss (100%)
        • First package decide the core.
        • Not choose itself?
          • 要怎麼決定成為 core? 透過什麼權值來證明它是好機器 ?
    • Cover the Sensing Field
        • 2R away from the nearest core node
          • Ownership (defined by its transmission range)
        • Core node can choose itself as a candidate
          • 結點少 , 自己判斷成為 core?
    • Probabilistic Subset
      • Scope sensing(ex:25%)
      • Triggers detected during the preliminary sensing
      • p% be candidate be core
    http://wshlab2.ee.kuas.edu.tw
        • <- 是否使用在對某些興趣點做訂閱時使用 ?
  • 23.
      • Environment considerations
        • Scarcity of bandwidth and energy.
      • Message considerations.
        • The protocol to consider large-sized messages only before. but WSN need small-sized queries.
        • So issues on what kind of loss recovery.
      • Reliability considerations
        • 100 percent reliable delivery to only a subregion.
    Introduction -D http://wshlab2.ee.kuas.edu.tw
  • 24. Related work -D
    • Before
      • Efficient flooding
        • Classify: probability-based, area-based and neighbor-knowledge-based
        • Can’t guarantee the reliability.
      • “ Minimizing Broadcast Latency and Redundancy in Ad Hoc Networks”
        • Broadcast tree and schedules transmissions.
        • Greedy strategy to minimize the latency and the number of retransmissions
        • Not suit large-scale networks
      • Pump Slowly, Fetch Quickly (PSFQ)
        • Relatively slow speed, using in-sequence forwarding.
        • Recover missing data packets from immediate neighbors.
        • Single-packet isn’t concider.
      • TinyDB : Query processor
        • Minimize power consumption
        • accuracy of query
        • No different services
    http://wshlab2.ee.kuas.edu.tw
  • 25.
    • Challenges
    • Environment Constraints
      • Not relying on statically constructed mechanism
        • dynamics of the network
      • Tremendous amount of spatial reuse.
    Problem definition -D http://wshlab2.ee.kuas.edu.tw
  • 26. Problem definition -D
    • Acknowledgment (ACK)/NACK Paradox
      • NACK
        • Effective loss advertisement mechanism.
        • Low loss probabilities are not inordinately high.(The package is small)
        • Can‘t handle the unique case. When lost message at a part of node.(The middle node die)
        • Not aware, it cannot advertise a NACK to request retransmissions.(The aware message disappear.)
      • ACK-based recovery
        • Focus on all-packet-lost problem.
        • 只能復原一個封包 ? 所以 WSN 會傳不到一個封包 ? 為了節省網路使用率 ? 還是能自救就自救 ? 這樣比較節省頻寬
        • Deficiencies of ACK implosion (big overhead). ( 過度確認問題 )
    http://wshlab2.ee.kuas.edu.tw
  • 27. Problem definition -D
    • Reliability Semantics
    http://wshlab2.ee.kuas.edu.tw
  • 28. GARUDA Design Element -D
        • 前言
          • 機制 Two-phase loss recovery strategy that uses out-of-sequence forwarding
          • 選舉系統 Simple candidacy-based approach for the core construction
          • Improve NACK-based.
    http://wshlab2.ee.kuas.edu.tw
  • 29. GARUDA Design Element -D
      • Instantaneous Core Construction
        • First packet delivery to determine the hop_count
        • 3i hop distance
        • Core lies
          • Constructed using a single-packet flood
          • Leveraged for more efficient and fair core construction.
    http://wshlab2.ee.kuas.edu.tw
  • 30. GARUDA Design Element -D
    • Multiple Reliability Semantics
      • SPT(short path tree) can shortly delay.
    http://wshlab2.ee.kuas.edu.tw 因為我沒探討其他信賴的題目
  • 31.
    • Loss Recovery Servers: Core
      • Goal
        • Minimize the retransmission overheads.
        • Constructed in a manner (the dynamic topology)
      • Rationale of Core
        • MDS(Minimum Domination Set)
        • MSC(Minimum Set Cover)
    Design Element http://wshlab2.ee.kuas.edu.tw
          • 定義 MDS 以及 MSC 的問題 , 指出他們在這個模型中的腳色及相關性
    MDS
  • 32. Design Element -D
      • A=PAPX(MDS)
      • B=OPT(MSC)
      • Cost = A/B
      • Classification
        • Case 1 = optimal
        • Case 2 = worst case
        • Case 3 = half good or worst
      • Sum up
        • Replacing by approximation ratio
        • Using Approximation MDS
        • is what?
    http://wshlab2.ee.kuas.edu.tw 重點 !! 詳細了解每個為什麼 建構的 cost G d :upper bound of the ratio
  • 33. Design Element
    • Loss Recovery Process
      • Out-of-Sequence Packet Forwarding with
      • A-Map(Availability Map)
      • Two-Stage Loss Recovery
        • Why does two-stage need?
          • Avoid collide
          • Single require
          • Second recovery short than two hops
        • Step
          • Loss recovery for core nodes
            • Uni-cast from upstream core
          • Loss recovery for noncore nodes
            • Use the overhead – A-MAP, it’s basic flooding.
    http://wshlab2.ee.kuas.edu.tw
  • 34. Design Element
    • Reliable Single-/First-Packet Delivery ? No relation
      • Predict , 重傳 when the first-packet missed. ?
      • Benefits
        • Robust fading effects ( 因為主動 )
        • Robust to collision ( 沒人在聽的時候還是會尋找 ?)
        • Implicit NACK (suit in short package )
        • Result in low energy
    http://wshlab2.ee.kuas.edu.tw
  • 35. Implicit ACK http://wshlab2.ee.kuas.edu.tw 802.11 Implicit ACK Gain