a comparison of wireless mobile ip movement detection methods for complex movement patterns

Workshop: IP in TelekommunikationsnetzenBremen, 25.1.01

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c no m e ts Kom m unikationsnetze

Universität Brem enA Comparison of Wireless Mobile IP Movement Detection

Methods for Complex Movement Patterns

A Comparison of Wireless Mobile IP Movement Detection Methods for Complex Movement Patterns

N. A. Fikouras and C. Görg

Department of Communication Networks

University of Bremen


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Contents

Introduction to Mobile IP Mobile IP Hand-offs

• Movement Detection Methods• Agent Selection• Agent Advertisements• Regional Registrations

Complex Movement Patterns Straight Line Back & Forth

Simulation Setup Simulation Results


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Mobile IP

MIP is an extension to IP Equivalent to the post office

forwarding service Enables IP Roaming Introduces IP Layer Hand-offs During Hand-offs the Mobile:

Detects Movement• Neighbouring Agent Discovery

• Agent Selection Registers

Hand-offs cause Packet Loss

Internet

A ccess Po in ts

R outer

fa .righ tH om e Agent

M obile N ode

sam .com ne ts

Fore ign A gen t

coyote.com ne ts

nom ad .com nets

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hom e.n iko.deStationa ry N ode

left.

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Movement Detection

Advertisement Based Requires Periodic Broadcast Agent Advertisements Agent Discovery = Movement Detection

Hint Based Requires Link-Layer Hand-off Information LL Hand-off Hint = Movement Detection Agents are solicited for Unicast Ads Periodic Advertising is not needed Solicited Ads = Agent Discovery

FA


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Agent Advertisements

Optimal Movement Detection requires high advertisement rates

High rates affect link throughput

Advertisements require the presence of Agents

Bibliography considers 100ms as optimal period

99%

97 .5%

95%

90%

80%

75%

00.1

0.20.3

0.40.5

0.60.7

0.80 .9

1

Advertisem ent Period (seconds)

48112

176240

304368

432496

Advertisem ent S ize (bytes)

130

140

150

160

170

180

190

200

210

Th

rou

ghp

ut (

KB

/sec

)

99%

97.5%

95%

90%

80%

75%w ith respect to th roughput foradvertisem ent s ize 48 bytes and period 1 sec

Throughput of an 914MHz Lucent WaveLAN DSSS radio interface with respect to MIP agent advertisement size and period


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Movement Detection Methods

Advertisement Based Lazy Cell Switching (LCS)

• Wait for Serving Agent to expire• Agent lifetime is 3 * Advertisement Period

(on average: 2,5*period) Eager Cell Switching (ECS)

• Hand-off upon Agent Discovery(on average: 0.5*period)

Hint Based Hinted Cell Switching (HCS)

• Solicit when „hinted“• Hand-off upon Agent Discovery

(Mobile Node – Agent Round Trip Time)


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Simulation Software

Network Simulator: a discrete event simulator from UCB/LBNL/VINT supports Mobile IP extended to support:

• LCS, ECS and HCS• Agent Selection as per

Sun Labs MIP• Regional Registrations

Screenshot from the Simulation Visualisation with the Network Animator (NAM)


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Simulation Setup

FA-MN link is wirelined+ No Wireless Loss

Hand-offs managed through manipulation of links

+ Controlled Cell Cross time Simulations terminated at 5%

relative error rate Simulation Traffic

RTP stream Emulates VAT traffic

• PCM encoding• 78 kbps• 200 octets/packet• 20 ms inter-packet delay

H A

Router

HA : H o m e A g e n t

FA

FA FA

FAFA

FAFA FA

GFA

FA

FA

MobileN ode

CNG FA : G ate w a y F o re ig n A ge n t

0.5ms100Mbps

CN : eC o rre s p on d e n t N o d

0.5ms100Mbps

3ms2Mbps

0.5ms100Mbps

0.5ms100Mbps


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Complex Movement Patterns

Simulation Scenarios 29 Location update frequency (locupd) rates

(0.1 locupd/sec – 20 locupd/sec) Mobile roams with a given rate on a per sec basis Variable time between location updates - uniform(0,2/rate)

• Represents variable cell size with constant size OR• Constant cell size with variable speed

Straight Line Movement (SLM)• Simulated topology: 50 FAs in a circle• With every completed circle all Agents are reinitialised

– Straight line movement without patterns

Back & Forth Movement (BnFM)• Simulated topology: 2 FAs


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SLM – Service Disruption

During MIP Hand-offs a Mobile may not

exchange traffic (Service Disruption) Unsuccessful Agent Selection leads to extended

Service Disruption ECS/HCS outperform LCS/fLCS

ECS/HCS Hands-off upon Agent Discovery

HCS outperforms ECS due to faster Agent Discovery ECS waits for the next periodic broadcast HCS is “hinted” movement through LL hints HCS may solicit for Unicast Ads.


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SLM – Service Disruption (cont.)

0

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0 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0

Ave

rag

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etw

ork

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dis

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(sec

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L oca tio n u pd a te fre q ue n cy ( locup d / se c )

A ve ra g e N e tw o rk S e rv ice D is ru p tio n fo r Stra ig ht L in e M ove m en t P a tte rns

E a g er C e ll S w itch ingL azy C e ll S w itch in g

H inted C e ll S w itch ingfa s t L a zy C e ll S w itch in g


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Agent Selection

Agent Selection is based on the LocalMaTable (Sun Labs MIP v1.2)

Selection Criteria: LCS (supported by Sun MIP):

• Always the Serving Agent when activeOR

• Agent with longest lifetime ECS/HCS:

• Most Recently Discovered AgentOR

• Agent with longest lifetime fast extension (fHCS, fLCS)

Ignore the LocalMaTable Make Agent Discovery based on

Solicitation/Unicast Ads. Agent Selection in Sun Labs MIP v1.2

… SE

AR

CHAdvRemainingLifetime

AdvSrcAddr

AdvRemainingLifetimeAdvSrcAddr



Loc

al M

obi

lity

Ag

ent T

abl

e


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BnFM – Service Disruption

In BnFM Service Disruption may be completed

without a prior MIP hand-off HCS faster Agent Discovery is not useful in BnFM.

There are no agents to be discovered. ! Agent Selection based on the LocalMaTable reacts

only in the case of Agent Expiration In HCS and with high lockupds expiration does not

occur due to hinted solicitation fHCS outperforms HCS due to more successful

Agent Selection The fast extension is not based on the LocalMaTable


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BnFM – Service Disruption (cont.)

0

0 .0 5

0 .1

0 .1 5

0 .2

0 .2 5

0 .3

0 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0

Ave

rag

e n

etw

ork

serv

ice

dis

rup

tion

(sec

)

L oca tio n u pd a te fre q ue n cy ( locup d / se c )

A ve ra g e N e tw o rk S e rv ice D is ru p tio n fo r B a ck & F orth M o vem e n t P atte rn s

E a g er C e ll S w itch ingL azy C e ll S w itch in g

H inted C e ll S w itch ingfa s t H in te d C e ll S w itch in g


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Conclusions (SLM) MIP hand-offs depend on Movement Detection MIP Movement Detection involves

Agent Discovery Agent Selection

LCS/fLCS, ECS are based on Agent Ads.- Slow or unsuccessful Agent Discovery

LCS, ECS are based on the LocalMaTable- Unsuccessful Agent Selection

HCS/fHCS are based on LL hand-off „hints“+ Faster Agent Discovery

In Straight Line Movement HCS outperforms fLCS/LCS, ECS


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Conclusions (BnFM) In Back & Forth Movement Agent Discovery performance is

not as important There are no new agents to be discovered Agent Selection is more critical

LocalMaTable based methods depend on Agent Expiration HCS does not expire agents due to solicitations

fHCS is based on the fast extension Ignores LocalMaTable+ Adapts to local Agent (Known or newly Discovered)+ Performs more successful Agent Selection

Packet loss is directly dependent on service disruption HCS/fHCS demonstrates constant best performance in both

Straight Line and Back & Forth Movement Patterns

a comparison of wireless mobile ip movement detection methods for complex movement patterns

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