Performing Gateway Load Balancing in MANETs
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Performing Gateway Load Balancing in MANETs PhD Dissertation February 10 th 2012 Vinh Pham. Vinh Pham, PhD Dissertation 2012. Outline. Introduction Motivation MANET Challenges Main focus of the Thesis Thesis overview Contributions Part I: Mobility

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Performing gateway load balancing in manets phd dissertation february 10 th 2012 vinh pham

Performing Gateway Load Balancing in MANETs

PhD Dissertation

February 10th 2012

Vinh Pham

Vinh Pham, PhDDissertation 2012


Outline

Outline

  • Introduction

    • Motivation

    • MANET

    • Challenges

    • Main focusoftheThesis

    • Thesisoverview

  • Contributions

    • Part I: Mobility

    • Part II: Loadbalancing for Intradomain

    • Part III: Loadbalancing for Interdomain

  • Concludingremarks


Motivation

Motivation

Improvingtheinformationflow in emergency and rescueoperations

  • Today

    • Mainly low bandwidth, single-hop, voice-only

  • Tomorrow

    • Based on MANET

    • Broadband multihop

    • Voice, data, video

    • Situationalawareness, e.g. positionsharing

    • Access criticalinformation: victim info, maps,

      • constructiondrawings


Manet what is it m obile a d hoc net work

MANET – What is it?Mobile Ad Hoc Network

B

Transmission range

A

C

  • Infrastructureless

  • Dynamic: mobility, join/leavethenetwork

  • Rapid deployment

  • Costeffective


Challenges

Challenges

  • Medium access: Contention-basedrandomaccess

    • Interference and collisions

  • Distributedrouting

    • Inconsistency and overhead

  • Link quality

    • Varying, affected by topography, weather etc.

  • Node mobility

    • Link breaks, packet loss, loss ofconnectivity

  • Network Capacity

    • Lowcapacity, limited scalability

      Need to overcomethesechallenges to achieve

      highernetworkperformance!


Main focus of the thesis

Main FocusoftheThesis

  • Mobility

    • Rerouting time due to mobility and link break

  • Loadbalancing

    • Intradomaintraffic

    • Interdomaintraffic


Overview of the work

Overview of the work

Part I

Part II

Part III


Contributions part i

Contributions Part I


Mobility

Mobility

  • Paper A

  • “Rerouting Time and Queueing in Proactive Ad Hoc Networks”

  • V. Pham, E. Larsen, K. Øvsthus, P. Engelstad and Ø. Kure, In proceedingsofthePerformance, Computing, and Communications Conference 2007 (IPCCC 2007), New Orleans, USA, April 11-13, 2007, pp. 160-169.


Motivation1

Motivation

  • Discovery: Rerouting due to mobility exceeds the expected 4-6 seconds.

B

A

C


The contributions

The contributions

  • Analysingthererouting time

  • Proposedsolution:

    Adaptive Retry Limit


Analysing a link break

Analysing a Link Break

Last Hello from C received at A

New routeto C.

Link is broken. A’squeuebeingfilled up.

Last successfull data transmission from A directly to C

Garbagepacketsarediscarded from A’squeue

A transmits data to C

B

A

C

I

II

III

QueueReductionPhase

QueueAccumulationPhase

Last Hello from C

te

td

t2

t3

t

t1

t0


Solution adaptive retry limit

Solution – Adaptive Retry Limit

Node A’sInterfaceQueue

Packet 7 is transmitted 1 time and discarded

Packet 2 is transmitted 6 times and discarded

Packet 1 is transmitted 7 times and discarded

9

8

9

8

7

7

7

1

8

2

9

9

8

2

3

3

In

Out

  • Assumption:

  • Retry limit = 7

  • All packetsto the same destination


Results

Results

Gain


Conclusion part i

Conclusion - Part I

  • Rerouting time is affected by:

    • Packetsize and rate

    • MAC layerqueuesize

    • MAC layerretries

  • Adaptingthe MAC layerretriesreducesthererouting time.


Contributions part ii

Contributions Part II


Load balancing for intradomain traffic

LoadBalancing for IntradomainTraffic

Paper B

“RoutingofInternalMANET Traffic over External Networks”

V. Pham, E. Larsen, K. Øvsthus, Ø. Kure and P. Engelstad, Mobile InformationSystems Journal, iiWAS/MoMM special issue, Volume 5, Number 3, 2009


Motivation2

Motivation

  • Transit routing → Load balancing for intradomain traffic

  • Alleviatetrafficload in the MANET

  • Improveperformanceofintradomaintraffic:

    • Throughput

    • E2E delay

    • Packetdeliveryprobability

650 kbps

300 kbps


Contributions

Contributions

  • Analysis and simulationoftransitrouting

  • Proposedsolution:

    Costmetricalgorithm for transitrouting


Solution the cost metric algorithm

Solution: The CostMetricAlgorithm

Cost for ad hoc path

Ci = k

Cost for wiredpath, nointerference

Cii = max(m,n)+c

Cost for wiredpath, withinterference

Cii = sum(m,n)+c

c = constantbetween 0 and 1


Evaluation

Evaluation

B

C

A

4

11

10

5

2

9

1

12

6

3

7

8

Transitroutingenabled

Transitrouting not enabled


Results1

Results

Averageenhancement = 40.3 %


Conclusion part ii

Conclusion - Part II

  • Enablingtransitroutingcan be beneficial

  • Reduceload in MANET

  • Increase E2E throughput

  • Reduce E2E delay

  • Increaseprobability for packetdelivery


Contributions part iii

Contributions Part III


Load balancing for interdomain traffic

LoadBalancing for InterdomainTraffic

Paper C-E

“PerformanceAnalysis of Gateway Load Balancing in Ad Hoc Networks with Random Topologies”

V. Pham, E. Larsen, K. Øvsthus, P. Engelstad and Ø. Kure and, Proceedings of The 7th ACM International Symposium on Mobility Management and Wireless Access (Mobiwac09), Tenerife, Canary Islands October 26-30, 2009

“GatewayLoadBalancing in Future Tactical Networks”,

V. Pham, E. Larsen, K. Øvsthus, Ø. Kure and P. Engelstad, IEEE Military Communications Conference 2010 (MILCOM 2010), San Jose, CA, USA, October 31 - November 3, 2010

“A Radio Load Based Gateway Load Balancing Scheme with Admission Control”

V. Pham, E. Larsen, Q. Le-Trung, P. Engelstad and Ø. Kure, Proceedings of the International Symposium on Wireless and Pervasive Computing

(ISWPC 2011), Hong Kong, China, February 23-25, 2011


Motivation3

Motivation

Global Internet

GW0

Bottleneck

GW1

Addressgatewayloadbalancing → Loadbalancing for interdomaintraffic

Focusonoutboundtraffic! Howevertheresult is

anticipated to be applicable for inboundtraffic as well!


Contributions1

Contributions

  • Analysing the nature of gateway load balancing (LB)

    • Explorefactorsthatimpacttheperformanceof LB

  • Proposedsolutions:

    • RLLB (Radio Load Based Load Balancing)

    • RLAC (Radio Load Based Load Balancing with Admission Control)


Analysis

Analysis


Factors that affect lb

Factorsthataffect LB

  • Shortcoming in previous work:

    • Simple and smalltopologies

    • Grid or constructedtopologies

    • Fewtopologies used in evaluation

  • Needs many random topologies to statistically explore factors affecting the benefit of LB

  • ~200 randomtopologies and thousandsofsimulations

  • Factorsthataffectperformanceof LB:

    • Offeredload– Gatewaydistance

    • Asymmetrylevel– Levelof spatial reuse/sensing range

    • Network shape and size

  • However, thesefactorsalonecannotexplainwhythebenefitof LB is high for certaintopologieswhile it is poor for others. The layout ofthetopology is a crucialfactor!


Congestion map

CongestionMap

# transmissions

The congested area represents an obstaclepreventingefficientreroutingoftraffic!

The efficiencyof LB dependsonwhere nodes arelocated relative to thecongestedcentre area

The centreofthe area is most congested, not the area aroundtheGWs!


Load balancing solution

Load BalancingSolution


Overview rlac architecture r adio load based l oad balancing scheme with a dmission c ontrol

Overview RLAC ArchitectureRadio Load Based Load Balancing Scheme with Admission Control


Radio load metric

Radio LoadMetric

Tbusy

time (sec)

Twindow

  • RL metric provides a measure for the condition in the network

  • Pros: The RL info is FREE! RL does not dependonactiveprobingsuch as in ETX, Packet Pair, RTT


Gateway selection

GatewaySelection

L0

L1

GW0

GW1

?

h0

h1

B0

B1

Gatewayselectionalgorithmneeds to consider:

The loadL at theGWs

The distanceh to theGWs

The bottleneckcapacityB to theGWs

Condition at theGWs

The propertiesofthepathtowards a specific GW


Synchronized rerouting

SynchronizedRerouting

  • Problem:

    • A groupof nodes maysimultaneously and repeatedlyreroutetheirtraffic back and forth from one GW to another.

  • Solution:

    • Use a randomizedratherthan a deterministic

    • gatewayselectionapproach!


Randomized gateway selection

RandomizedGatewaySelection

Deterministic:

IfGWn is leastcongestedthenselect it as default GW

Randomized:

1.

Draw a randomnumberR∈ [0,1],

and let theoutcomedecide

2.


Randomized gateway selection example

RandomizedGatewaySelectionExample

R5

R3

R4

0

1

P0=1/3

P1=2/3


Admission control ac

Admission Control (AC)

  • AC prevents traffic load from reaching a critical high level

  • AC is enabled/disabled using: L, B and h

  • When the network load is high:

    • Preempt nodes fartherawaywhilegivingpriority to nodes closer to theGWs

    • Cost is higher to send packets for nodes farther away

    • Reasonable to enable AC on nodes that have very low packet delivery ratio

  • Disadvantage: Unfairness


Results2

Results


Static topologies 1

StaticTopologies (1)

TS1

TS2


Static topologies 2

StaticTopologies (2)


Mobile topologies

Mobile Topologies


Performance of lb in mobile topologies

Performanceof LB in Mobile Topologies

The performanceof LB is lower in mobile topologiescompared to statictopologiesbecause:

  • More challenging to perform LB in mobile topologies:

    • Link breaks, shorter link life time and lowereffectivecapacity

    • Cannotcapturethechanges in thetopology fast enough due to the inherent delay in theroutingprotocol.

    • The solution in paper A can be used to improveperformance

  • Condition for evaluation not same. LB is onlyfeasible/ beneficial for a certainamountofthesimulation time:

    • Lowasymmetrylevel or theload is evenlydistributed

    • Partitioning


Conclusion part iii

Conclusion - Part III

Performanceof LB is affected by:

  • Asymmetrylevel, offeredload, sensing range,…

  • Layout oftopology

    Staticasymmetrictopologies

  • LB canimproveperformance

    Mobile topologies

  • More challenging

  • Lowmobility: moderate enhancement

  • Highmobility: low/noenhancement


Concluding remarks

Concluding Remarks

  • We are not there yet:

    • Challenges need to be solved before we can realize a communication system of tomorrow

  • Challenges addressed in this thesis:

    • Mobility – rerouting time

    • Load balancing – Intradomain and interdomain traffic

  • Increased understanding has been provided through this work

  • Proposed solutions that increase the network performance


Thank you

Thank You!


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