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GARUDA: Achieving Effective Reliability
for Downstream Communication inWireless 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
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Data delivery can be critical
Guaranteed sink-to-sensors
Reliable downstream data
Abstract
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Outline
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IntroductionEnergy-aware protocols isn’t enough
Wireless Channel Errors Congestion and Contention Broadcast Storm
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Delivered reliably Control code Query-data Response result about sensor match data
Cornerstones of design Reliable short-message. Virtual infrastructure – core Two-stage negative acknowledgment (NACK)
Introduction
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Assumptions Downstream reliability Communication and node failures 100 % reliable message delivery Message size less then one packet Network model is static
Framework
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Single-/First-Packet Delivery Benefits
• Robust fading effects and collision.
• Implicit NACK fit in short package.
• Result in low energy.
Framework
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Framework Wait for first package(WFP) Pulse Transmission
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CS: carrier sensin
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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
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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– S0 is S1’s core ,when the new S0’ core invite again, S1 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.
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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
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),,,( vFlagbIdmapACid
),,( bIdmapANCC idid
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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
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Performance evaluation
Evaluation of Single-Packet Delivery
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Performance evaluation
Evaluation of Multiple-Packet Delivery
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(100 * 3.14 * 67 * 67) / (650 * 650) = 3.33620355(800 * 3.14 * 67 * 67) / (650 * 650) = 26.6896284
Performance evaluation Microscopic Analysis
Optimality of the core A-map overhead Number of recovery
events Effect of random wireless
errors
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Performance evaluation
Evaluation of Variants Reliable Delivery within a Subregion
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Performance evaluation Minimal Set of Sensors
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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?
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Framework –D?Two-Phase Loss Recovery
A-Map(Availability Map)
Function• Loss detection
• Loss recovery
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Performance evaluationSimulation 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
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Other reliability semanticsReliable 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
<- 是否使用在對某些興趣點做訂閱時使用 ?
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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
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Related work -DBefore
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
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ChallengesEnvironment Constraints
Not relying on statically constructed mechanism• dynamics of the network
Tremendous amount of spatial reuse.
Problem definition -D
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Problem definition -DAcknowledgment (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 )
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Problem definition -DReliability Semantics
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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.
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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.
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GARUDA Design Element -D
Multiple Reliability Semantics SPT(short path tree) can shortly delay.
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因為我沒探討其他信賴的題目
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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
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
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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?
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重點 !! 詳細了解每個為什麼
建構的 cost
)ln()(
)(k
MSCOPT
MSCAPX
dG
SMSCOPT )(
Gd :upper bound of the ratio
d
d
G
G
S
S
MSCOPT
MDSPAPX
)(
)(
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Design ElementLoss 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.
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Design ElementReliable 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
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Implicit ACK
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802.11
Implicit ACK
Gain