Performance Analysis of Performance Analysis of Decentralized RAN Decentralized RAN

(Radio Access Network) (Radio Access Network) Selection SchemesSelection Schemes

December 28December 28thth, 2004, 2004

Yang, SookhyunYang, Sookhyun

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ContentsContents

IntroductionIntroduction

Previous WorksPrevious Works

RAN Selection SchemesRAN Selection Schemes

Evaluation MethodEvaluation Method

Performance AnalysisPerformance Analysis

ConclusionConclusion

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BackgroundBackgroundEmerging various wireless access technologiesEmerging various wireless access technologies– 2G, 3G celluar, satellite, WiBro/WiMax (IEEE 802.16), Wi-Fi (IEEE 2G, 3G celluar, satellite, WiBro/WiMax (IEEE 802.16), Wi-Fi (IEEE

802.11a/b/g), Bluetooth (IEEE 802.15)802.11a/b/g), Bluetooth (IEEE 802.15)

In the Fourth-generation (4G) wireless networkIn the Fourth-generation (4G) wireless network– Multiple broadband wireless accessMultiple broadband wireless access– Seamless mobility across heterogeneous networksSeamless mobility across heterogeneous networks

(HPi)

WWAN: large coverage, high cost

WLAN: high speed, moderate cost

WPAN: small area, low speed, low cost

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MotivationMotivation

RAN DiscoveryRAN Discovery– Discover available access networDiscover available access networ

ksks– Scan a wide range of frequencieScan a wide range of frequencie

ss– Power managementPower management

RAN selectionRAN selection– Determine the optimal access neDetermine the optimal access ne

twork among available RANstwork among available RANs– Many selection parametersMany selection parameters

User’s network preferenceUser’s network preferenceCommunication chargeCommunication chargeAvailable bandwidthAvailable bandwidthPower dissipationPower dissipation

Bluetooth

Wi-Fi

Satellite

WiMax

Celluar

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Previous WorksPrevious WorksCentralized approachesCentralized approaches– A centralized server collects and monitors available RANsA centralized server collects and monitors available RANs– A centralized server manages a mobile host’s position (GPS)A centralized server manages a mobile host’s position (GPS)– BAN (Basic Access Network)-based schemeBAN (Basic Access Network)-based scheme– WISE (Wise Interface Selection)WISE (Wise Interface Selection)

Decentralized approachesDecentralized approaches– A mobile host itself monitors available RANsA mobile host itself monitors available RANs– PPM (Power and Performance Management)PPM (Power and Performance Management)– NAV (Network Allocation Vector)-based schemeNAV (Network Allocation Vector)-based scheme

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Decentralized Decentralized ApproachesApproaches

RAN discoveryRAN discovery– Periodically turns on NICs (Network Interface Card) Periodically turns on NICs (Network Interface Card) – Static or Dynamic periodStatic or Dynamic period– All NIC or a CAN (Candidate Access Network)All NIC or a CAN (Candidate Access Network)

RAN selectionRAN selection– QoS guaranteeQoS guarantee– Signal strength is increasingSignal strength is increasing– Minimum power consumptionMinimum power consumption– Select before a handoff occursSelect before a handoff occurs– Handoff occurs when QoS does not guaranteeHandoff occurs when QoS does not guarantee

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How to discover available RANsHow to discover available RANs

Static/Dynamic periodStatic/Dynamic period– Static period Static period ∝ ∝ {network’s coverage}{network’s coverage}

– Dynamic period Dynamic period ∝∝

– {mobile host’s velocity} ≈ { signal strength}∆{mobile host’s velocity} ≈ { signal strength}∆

CAN (Candidate Access Network)CAN (Candidate Access Network)– Pre-select the optimal RAN among available RAN as a CANPre-select the optimal RAN among available RAN as a CAN– Periodically check that a selected CAN guarantees QoSPeriodically check that a selected CAN guarantees QoS

{network’s coverage}{network’s coverage}{mobile host’s velocity}{mobile host’s velocity}

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How to select the optimal How to select the optimal RANRAN

Available bandwidthis maximum?

YES

YES

Signal strength is increasing?

Power consumptionis minimum?

I f there is no QoS-guaranteeing access network

Optimal Access Network

QoS <= Available bandwidth

Available Access Network

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ObjectiveObjective

Evaluate the performance of the following Evaluate the performance of the following RAN selection schemesRAN selection schemes– Static period with a CANStatic period with a CAN– Dynamic period with a CANDynamic period with a CAN– Static period without a CANStatic period without a CAN– Dynamic period without a CANDynamic period without a CAN– Continuously active schemeContinuously active scheme

Performance MetricsPerformance Metrics– Achieved bandwidthAchieved bandwidth– Number of handoversNumber of handovers– Power consumption per secondsPower consumption per seconds

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Evaluation EnvironmentsEvaluation Environments

AP

BS

NS2’s mobility generator

2.4MbpsSignal is Good~!

1.2MbpsSignal is not good~!

0MbpsSignal is bad~!

BS BS

AP

AP

BS

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ConfigurationConfigurationMobile nodeMobile node– 100 nodes, maximum 11m/s (100 nodes, maximum 11m/s (≒ ≒ 40km/h)40km/h)– Equipped with all types of network interfacesEquipped with all types of network interfaces

Network characteristicsNetwork characteristics

Coverage(Km)

Bandwidth(Mbps)

Type

2.5 2.4CDMA1X

1 5802.16

0.4 54802.11a

0.4 11802.11b

0.4 54802.11g

Transmit(J/Mbits)

Idle(W)

Receive(J/Mbits)

1.169 0.0820.206

(0.264) (0.2)(0.13)

0.022 10.035

0.205 0.750.123

0.037 0.750.026

Off(W)

ON(W)

- -

- -

- -

1.7(1ms)2.3(0.3s)

- -

Power Consumption

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Network TopologiesNetwork Topologies

(a)Insufficient network resource

(b) Sufficient network resource

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Achieved bandwidthAchieved bandwidth

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Achieved

bandwidth

(Mbps)

0.1 0.2 0.4 0.8 1.6 3.2

Target bandwidth (Mbps)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Achieved

bandwidth

(Mbps)

0.1 0.2 0.4 0.8 1.6 3.2

Target bandwidth (Mbps)

(a) Insufficient network resource (b) Sufficient network resource

Performance Analysis (1/3)Performance Analysis (1/3)

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Number of handoversNumber of handovers

0

5

10

15

20

25

30

35

40

45

50

Number

of

handoff

0.1 0.2 0.4 0.8 1.6 3.2

Target bandwidth (Mbps)

0

5

10

15

20

25

30

35

40

45

50

Number

of

handoff

0.1 0.2 0.4 0.8 1.6 3.2

Target bandwidth (Mbps)

(a) Insufficient network resource (b) Sufficient network resource

Performance Analysis (2/3)Performance Analysis (2/3) QoS degradation

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Power consumption per Power consumption per SecSec

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Power

consump-

tion(W)

0.1 0.2 0.4 0.8 1.6 3.2

Target bandwidth (Mbps)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Power

consump-

tion(W)

0.1 0.2 0.4 0.8 1.6 3.2

Target bandwidth (Mbps)

(a) Insufficient network resource (b) Sufficient network resource

Performance Analysis (3/3)Performance Analysis (3/3)

4.5 ~ 40% of a

continuously active

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Observations and Observations and AnalysisAnalysis

Four selection schemes show the same Four selection schemes show the same achieved bandwidthachieved bandwidth

Dynamic or a CAN give large energy-Dynamic or a CAN give large energy-savingsaving

But, when bandwidth is sufficientBut, when bandwidth is sufficient– Static/dynamic with a CAN trigger too many Static/dynamic with a CAN trigger too many

handovershandovers

But, when bandwidth is not sufficientBut, when bandwidth is not sufficient– Static with a CAN consumes more power than Static with a CAN consumes more power than

Dynamic without a CANDynamic without a CAN

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ConclusionConclusion

Evaluated decentralized approaches for Evaluated decentralized approaches for RAN selectionRAN selection

Implemented a simulator for wireless Implemented a simulator for wireless overlay network environmentoverlay network environment

Dynamic with a CAN reduces large amount Dynamic with a CAN reduces large amount of power consumption without degrading of power consumption without degrading achieved bandwidthachieved bandwidth

But, too many handovers occur when But, too many handovers occur when bandwidth is sufficientbandwidth is sufficient

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NetworkAdapter #1

NetworkAdapter #2

NetworkAdapter #3

A CAN is NOT valid!

time

time

time

0

0

0

Candidate

ALL

QoS guarantee check

QoS guarantee checkCandidate

ALL

Candidate

ALL

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Network TopologiesNetwork Topologies

(a)Insufficient network resource

(b) Sufficient network resource

CDMA1X(4)

802.11b(31)

802.11g(10) 802.16

(10)

802.11a(10)

CDMA1X(4)

802.16(20)

802.11a(21)

802.11g(26)

802.11b(25)

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