GARUDA

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

http://wshlab2.ee.kuas.edu.tw

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

http://wshlab2.ee.kuas.edu.tw8

CS: carrier sensin


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.


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


),,,( 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



Performance evaluation

Evaluation of Single-Packet Delivery

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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




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



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 )



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.




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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Multiple Reliability Semantics SPT(short path tree) can shortly delay.


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?


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


Implicit ACK


802.11

Implicit ACK

Gain

Technology

GARUDA