Systems Optimization for Mobility Management

Systems Optimization for Mobility Management

Ashutosh DuttaElectrical Engineering Department

Columbia UniversityMarch xx, 2010

Outline• Motivation

• Vision

• Key Contributions

• Sample results

• Conclusions and Future work

Motivation• Cellular mobility typically involves handoff across

homogeneous access technology – Optimization techniques are carefully engineered to improve

the handoff performance• IP-based mobility involves movement across access

technologies, administrative domains, at multiple layers and involve interaction between multiple protocols– Mechanisms and design principles for optimized handover

are poorly understood– Currently there are ad hoc solutions for IP mobility

optimization, not engineering practice – No formal methodology to systematically discover or

evaluate mobility optimizations – No methodology for systematic evaluation or prediction of

"run-time" cost/benefit tradeoffs

Backbone

AdministrativeDomain B

L2 PoA

Corresponding Host

128.59.10.7

IPch

207.3.232.10

207.3.240.10

128.59.11.8

N2

N1N1

N2

N1- Network 1 (802.11)N2- Network 2 ( CDMA/GPRS)

ConfigurationAgent

L3 PoA 207.3.232.10

MobileHost

AuthenticationAgent

Authorization Agent

RegistrationAgent

RegistrationAgent

Administrative Domain A

ConfigurationAgent

Authorization Agent

SignalingProxy

AuthenticationAgent

SignalingProxy

L3 PoA

L2 PoA

L2 PoA

L2 PoA

L2 PoA

L2 PoA

L3 PoA

Mobility Illustration in IP-based 4G network

128.59.9.6900 ms media interruption

802.11 802.11

802.11802.11

4 Seconds media interruption

Handoff Delay~ 18 s

802.11 CDMA

18 Seconds media interruption

L3 PoA

A

B

CD

What is the vision?• IP-based mobility needs to provide handoff

performance comparable to cellular mobility• In order to transition ad hoc optimization

approaches to engineering best practice we need the following:– Framework or model that can analyze the mobility event

in a systematic way, can verify and predict the performance under systems resource constraints

– A set of fundamental design principles to optimize handoff components across layers

– A set of well defined methodologies to verify the optimization techniques for mobility in an IP-based network

My Key Contribution

1. Identification of the fundamental properties that are rebound during handover event and systematic analysis of the operations that are intrinsic to handover

2. Modeling of the handover process that allows performance predictions to be made for both an un-optimized handover and for specific optimization methodologies under systems resource constraints and data dependency

3. Development of series of optimization techniques based on fundamental rules of optimization that could be applied to link, network, and application layers and preserve the user experience by optimizing the handover related delay and packet loss

4. Proof-of-concept of these handoff optimization techniques by building experimental systems and comparing these results with model-based prediction

Systems analysis of handoff components

MobilityEvent

Network discovery &selection

Networkattachment

Configuration Securityassociation

Bindingupdate

Mediareroute

Channeldiscovery

L2 association

Routersolicitation

Domainadvertisement

Identifieracquisition

DuplicateAddressDetection

AddressResolution

Authentication

Keyderivation

Identifierupdate

Identifiermapping

Bindingcache

Tunneling

Buffering

Forwarding

Bi-casting/Multicasting

Serverdiscovery

IdentifierVerification

Subnetdiscovery

P1 P2 P3 P4 P5 P6

P11

P13

P12

P21

P22

P23

P31

P32

P33 P41

P42P51

P52

P53

P54

P61 P62

P63

P64

System decomposition of handover process

Handover: Distributed operation across multiple layers

Time

L2PoA

L3PoA

Discovery Attachment Configuration

SecurityAssociation

p11

p12

p21

p31

p32 p42

p41Server(Proxy,/HA)

p22

Binding Update

MediaRerouting

p51p31

p32

p41 p42

p42 p63

p62

p13p23

p31

p33

MN

p11 p12 p21 p22p31 p41

p61p32 p42

p13 p23p33 p51

p51

p52

p52

CN

p42 p52p61

p54

p53 p54

p61

p61p62

p64p51

Mobility/Function

AccessType

Network Discovery

Resource Discovery

TriggeringTechnique

DetectionTechnique

Configuration

Key exchange/Authentication

Encryption BindingUpdate

MediaRerouting

GSM TDMA BCCH FCCH ChannelStrength

SCH TMSI SRES/A3 DES MSCContld.

Anchor

WCDMA CDMA PILOT SYNCChannel

ChannelStrength

Frequency TMSI SRES/A3 AES Network

Control

Anchor

IS-95 CDMA PILOT SYNCchannel

ChannelStrength

RTC TMSI Diffie-HellmanAKA

Kasumi MSCContld.

AnchorMSC

CDMA1X-EVDO

EVDO PILOTChannel

SYNCChannel

Channel

Strength

RTC TMSI Diffie-Hellman/CAVE

AES MSC PDSN/MSC

802.11 CSMA/CA

Beacon11R

11R802.21

SNR atMobile

Scanning.ChannelNumber,SSID

SSID,Channel number

Layer 2 authenticate802.1XEAP

WEP/WPA802.11i

Associate IAPP

Cell IP Any Gatewaybeacon

Mobilemsmt.

AP

beacon

ID

GW Beacon MAC

Address

AP address

IPSec IPSec RouteUpdate

IntermediateyRouter

MIPv4 Any ICMPRouter adv.FA adv.

ICMP

Router

Adv.

FA adv.L2 triggering

FA adv FA-CoACo-CoA

IKE/PANAAAA

IPSec MIPRegistration

FARFAHA

MIPv6 Any StatelessProactive

CARD802.2111R

RouterAdv.

RouterPrefix

CoA IKE/PANAAAA

IPSEC MIP updateMIP RO

CHMAPHA

SIPM Any StatelessICMP Router

802.2111R

L3RouterAdv.

Router Prefix, ICMP

CoAAORRe-Register

INVITE exchange/AAA

IPSEC/SRTP/S/MIME

Re-INVITE

B2BUACHRTPtrans

Functional Matrix of Mobility Event

MN pAR nAR HA CN

L2 Handoff

BU

BAck

Router Advertisement (Rtr Adv)

Router Solicitation (Rtr Sol)

Neighbor Solicitation (NS)

Neighbor Advertisement (NA)

[MN-CoA:CN] [MN-HoA:CN] [Data Tunneling] [MN-HoA:CN] [Data]

HoTI HoTI

CoTI

HoT HoT

CoTBU

BAck

Data Traffic at nPoA

Addressuniqueness

Movement Detect

Bin

ding

Upd

ate

Ret

urn

Rou

tabi

lity

Rou

te O

ptim

izat

ion

nAP AAAProbe Request

Probe Response

Beacon

Open Authentication

EAP-OL EAP-TLS

EAP Success

L2 Association

Layer 3configuration

4-way handshake

Discovery

Authentication

L2SecurityAssociation

Data

L3 Handoff

Handoff Analysis of Mobile IPv6

Proposed optimization techniques for handoff components

Proposed optimization techniques for respective handoff components

Handoff

components

Fundamental

principles

My proposed

optimization

techniques

Key

advantages

My

publications

Related

work

Discovery - Proactive discovery - Caching neighboring

network elements

and parameters

Application layer proactive discovery of network and resources

- Access

independent

- Eliminates

layer 2 scanning

delay

1. ACM Mobiquitous 2005

2. IEEE Broadnets 2006

3. IEEE 802.21 (2005)

• Selective scanning for 802.11 (Shin et al.)• Periodic scanning

(Montavont et al.)• Search in parallel with data (Velayos et al.)

Detection of

network

attachment

- Cross layer event triggers

- Policy-based approach based on mobile’s movement and type of application

-Link layer event triggers to expedite network detection or loss of network

- Use of cross layer information and policy to limit the binding update

-Speed up the execution of upper layer operations- Avoids the un-necessary binding update overhead

- Policy-based approach

1. IEEE WTC 2006

2. Springer Journal 2007

3. IEEE 802.21 (2005)

4. IEEE Wireless Communication Magazine

5. IEEE MILCOM

Teraoka et al.

Politis et al.

Carli et al.

Lee et al.

Zeadaly et al.

Configuration -Network assisted duplicate address detection- Reduction of signaling between mobile and server

- Caching of network identifier address

- Router assisted Duplicate Address Detection

- Client does not perform DAD

1. IEEE Sarnoff 2005

2. 2007 Springer

Journal on Wireless Personal Communication

Optimistic DAD

Passive DAD

Rapid Commit RFC 4039

- Proactive IP address acquisition

- Network layer configuration delay is avoided

Proposed optimization techniques for respective handoff components (contd.)

Handoff

components

Fundamental

principles

My proposed

optimization

techniques

Key

advantages

My

publications

Related

work

Binding Update Limit the binding update traversal

distance

- Anchor assisted hierarchical binding update for network layer and application layer mobility protocol

- Reduction in global signaling overhead

1. IEEE PIMRC 2004

2. ACM MC2R

3. IEEE MILCOM 2005

4. IEEE Wireless

Communication

Magazine 2003

5. IEEE Wireless Magazine 2008

MIP-RR

RFC 4857

HMIPv6 RFC 4140

Infrastructure-based single host

mobility

- Proactive

binding update

- Eliminates the binding update delay completely

- Limit binding update delay based on cross layer triggers (e.g., layer 2 and application layer)

- Mobility optimization based on mobility pattern and application- Increases throughput by 50 %

Multi-layer

Mobility

- Policy-based

approach based on mobile’s movement and type of application

- Cross layer triggers

1. IEEE MILCOM

2002, 2003

2. IEEE Wireless

Communication

magazine

3. Wiley journal on

Computer

communication

Proposed optimization techniques for respective handoff components (contd.)

Handoff

components

Fundamental

principles

My proposed

optimization

techniques

Key

advantages

My

publications

Related

work

Layer 3 security

association

- Limit the signaling exchange between authenticator and mobile for key generation

- Network layer assisted pre-authentication

- Access independent

- Enables pre-authentication across administrative domains

1. ACM Mobiquitous

2005,

2. ACM Mobiquitous 2007

3. IRTF MOBOPTS 2005

4. IEEE WCM magazine

2008

5. HOKEY WG

6. ACM MC2R 2005

7. ACM WMASH 2004

802.11i

802.11r

Context transfer

(e.g., Bargh et al.)

Forte el al.

- Avoid re-keying process

- Maintain security association using an

Anchor agent

- Minimal

infrastructure

change

- Works with any mobility protocol

Miu et al.

Bahl et al.

Rodriguez et al.

(context transfer)

Binding update

(contd.)

- Retransmission of

binding update- Simultaneous binding update - Forwarding or caching of binding update

- Location Proxy- Binding update Proxy

Eliminates vulnerability interval

1.IEEE MILCOM

2. IEEE Wireless

Communication

Magazine

3. Wiley Journal on

Computer

Communication

Tilak and Ghazaleh

Dreibholz et al.

- Soft handoff approach- Timer-based retransmission

- Can be implemented easily

Simultaneous

mobility

- Simultaneous bindings- Receiver and sender assisted approaches

-No significant increase in handoff

latency

Proposed optimization techniques for respective handoff components

Media

re-routing - Position media redirection entity closer to the mobile

- Maintain direct path between communicating hosts for packet delivery

- Transient redirection of in-flight data from previous network

- Reduces the packet loss during handoff by 60%

1. IEEE Wireless

Communication Magazine 2003

2. IEEE PIMRC 2006

3. IEEE Wireless

Communication Magazine 2008

4. IEEE WCNC 2007

FMIPv6

Malki et al.

Moore et al.

Krishnamurty et al.

RFC 3775

Wu et al.

SIP

Unicast

- Small group multicasting - Works well for multiple number of neighboring networks

- Edge network buffering - Dynamic buffering adjusts the buffer size based on handoff delay and reduces packet loss to zero

-Packet interceptor to change the source and destination address of the end nodes

-40 % latency improvement for small packets -- Only application layer changes in the MN and CN

Multicast -Reduction in

“JOIN” latency-Reduction in “Leave” latency- Hierarchical multicast approach

- Proactive JOIN- Proxy assisted Leave- JOIN during registration

- No tunnel overhead-Application layer triggering

- Suitable for intra-domain mobility

1. NOSSDAV 99

2. ICC 2001

3.IEEE Communication

Magazine, 2004

Wu et al.

McAuley et al.

Lin et al.

Handoff

components

Fundamental

principles

My proposed

optimization

techniques

Key

advantages

My

publications

Related

work

Modeling Mobility

Why Mobility Model ?• Optimization techniques of a mobility event can be designed

based on precedence relations amongst events and concurrent, conflicts or resource sharing type operations

• Need a framework and model – to analyze and schedule handoff processes for systems optimization – to conduct trade-off analysis between systems resources and

performance metrics

• Specific expected results– Determine the maximum parallelism possible between handoff primitives – Determine handoff delays based on the execution of primitive operations

under constraints of limits on parallelism and constraints on the use of shared resources

– A methodology to verify the systems performance of a specific optimization technique

– A methodology that can help design the optimal path of sequence of execution of events

Specifics of IP-mobility model

• Mobility event exhibits concurrent, sequential, conflicts or resource sharing behavior similar to a Flexible Manufacturing Systems (FMS)

• Handoff-related processes can be modeled as Discrete Event Dynamic Systems (DEDS) that span across layers and include multiple protocols

• I use Deterministic Timed Transition Petri Net (DTTPN) to evaluate and predict the performance of the system that demonstrates parallelism, optimistic or speculative operations

Modeling Steps

• Determine data dependency of mobility events

• Analyze the resource consumption for handoff components

• DEDS Modeling of various handoff components

• Systems performance for handoff events

• Scheduling of handoff functions

• Verification of behavioral properties e.g., deadlock

Dependency analysis of mobility eventsHandoff Process Precedence

RelationshipData it depends on

P11 – Channel Discovery P00 Signal-to-Noise Ratio valueP12 – Subnet discovery P21,P22 Layer 2 beacon ID

L3 router advertisementP13 – Server discovery P12 Subnet address

Default router addressP21- Layer 2 association P11 Channel number

MAC address Authentication key

P22- Router solicitation P21, P12 Layer 2 bindingP23- Domain advertisement P13 Server configuration

Router advertisementP31 – Identifier acquisition P23,P12 Default gateway

Subnet address Server address

P32 – Duplicate addressDetection

P31 ARPRouter advertisement

P33 – Address resolution P32, P31 New identifierP41 – Authentication P13 Address of authenticatorP42 – Key Derivation P41 PMK (Pairwise Master Key) P51 – Identifier update P31,P52 L3 Address

Uniqueness of L3 addressP52 – Identifier verification P31 Completion of COTIP53 – Identifier mapping P51 Updated MN address

at CN and HAP54 – Binding cache P53 New Care-of-address mappingP61 – Tunneling P51 Tunnel end-point address

Identifier addressP62 – Forwarding P51, P53 New address of the mobileP63 – Buffering P62, P51 New identifier acquisition P64 – Multicasting/Bicasting P51 New identifier acquisition

Resource usage per mobility eventsSub transitions

Sub-operations Resource Consumption

Bytes exchanged CPU samples Power (nano joules)

t00 Layer 2 un-reachability test 43 5 51600t01 Layer 3 unreachability 86 3 103200t11 Discover layer 2 channel 109 3 130800t12 Discover layer 3 subnet 110 4 132000t13 Discover server 126 5 540000t21 Layer 2 association 99 2 118800t22 Router solicitation 70 4 84000t23 Domain advertisement 226 4 271200t31 Identifier acquisition 1426 5 1711200t32 Duplicate address detection 164 6 196800t33 Address resolution 60 3 72000t41 Layer 2 open authentication 94 3 112800t42 Layer 2 EAP 2842 6 3410400t43 Four-way handshake 504 4 604800t51 Master key derivation (PMK) 0 10 0

t52 Session key derivation (PTK) 0 6 0

t61 Identifier update 204 4 422400t62 Identifier verification 148 6 177600t63 Identifier mapping 0 8 0t64 Binding cache 0 3 0t71 Fast binding update 110 3 132000

t72 Local caching 0 6 0

t81 Tunneling 60 2 72000t82 Forwarding 100 2 120000t83 Buffering 120 3 144000t91 Local id mapping 40 4 48000

t92 Multicasting/bicasting 192 2 230400

0% 20% 40% 60% 80% 100%

Battery

Bandwidth

CPU

Type

s of

reso

urce

s

Percentage of resources usage

L2 beacon adv

L2 Active Scanning

L2 Association

Open Authentication

EAPOL

4-Way handshake

Router Solicitation

Router Advertisement

DHCP

DAD

Binding Update

COTI

L3 unreachability

Server Discovery

L2 unreachability

t1 t2b. Conflict

P1

p1

p2

p1

p2

p1

p2

t1

t2

t3

f. Confusion

P1 t1 t2 P3

a. Sequential

c. Concurrent

p1

p2

t1

t2

P3

e. Merging

p1

p2 p3

t1

t2

g. Mutual exclusiveh. Priority

t1

d. Data dependency

i. Cyclici. Cyclic

Sample Petri Net Primitives

Pa Pb

Pa Pb

Pa

Pb

Pa

Pb

tc

Pa

Pb

pb

pa

tc

tc

ta tc tb

ta tbta

tc tb

tc ta

tb

ta

tb

pa starts before pb

pa meets pb

pa overlaps pb

pa during pb

pa starts pb

pa finishes pb

pa starts with pbpa

pb

tc

tb

tc tata

tb

Capturing sequence of handoff operations in Timed Petri Nets

01/06/2009 HICSS-42 26

Petri Net Approach to Systems Modeling in IP-based Handoff

ConnectedP8

Disconnected

NetworkAttached

Mobile NodeAuthenticated

SecurityAssociationEstablished

Identifier Updated

P1 P2 P3

P4P5AP6

P0

t1

t2t3

t4

t5t6t8

P7

t7

t9

t0

PM

PP

PB2

P5B

NetworkDiscovered

Mobile NodeConfigured

01/06/2009 HICSS-42 27

Hierarchical Representation- Handoff Sub-processes

NetworkResourceDiscovery

ConfigurationProcess

NetworkAttached

MobileConfigured

NetworkDetectionProcess

P1 P2 P3P0t2

t3

p01

p02

p03

t01

t02 t03ChannelDiscovery

Subnet discovery

Serverdiscovery

P11 P12 P13

t11 t12 t13

NetworkDiscovered

p21

p22

p23

L2association

Routersolicitation

DomainAdvertisement

t22

t21

t23

t1



Addressresolution

28

Places of Petri Net model for IP-based mobility

Places Description

P0 Mobile node is in disconnected state

P1 Network and resources discovered

P2 Target network selected

P3 Mobile node is configured and registered

P4 Mobile node is authenticated

P5A, P5B Security association is established

P6 Binding update is complete

P7 Intra-domain binding update is complete

P8 Mobile is connected state

PB Bandwidth resources

PM Memory resources

PP CPU resources

29

Transitions for Petri Net Model for IP-based mobility

Transition Description

t0 Mobile node gets disconnect trigger

t1 Mobile node discovers the network and resources at the new PoA

t2 Mobile node selects the network

t3 Mobile node goes through configuration and registration

t4 Mobile node goes through authentication process

t5 Mobile node goes through key derivation and security association process

t6 Mobile node goes through binding update process

t7 Mobile node goes through hierarchical binding update

t8 Data gets redirected to the mobile node

t9 Data gets redirected to the mobile node

Verification of handover systems performance using Petri net

1. Cycle time of Deterministic Timed Petri net– Minimum cycle time (C) is an indicator of maximum

performance– Determines which specific sequence of transition during a

handover provides minimum handover delay

2. Floyd algorithm– S matrix is formed out of token loading matrix, transition matrix

and distance matrix– Inspection of the diagonal elements of matrix “S” indicates

whether systems meets the required performance

3. Resource Time Product (RTP)4. Performance evaluation using MATLAB-based Petri net

Tools– Coverability Tree, Incidence matrix help determine system

behavior

Configuration Example (DHCP)

Mobile Server DHCP Discover

DHCP Offer

DHCP Request

Processing

Processing

ProcessingDHCP ACK

ARPING (anybody has this address)

Waits foran answerto check address

Assignsaddress

Updates ARP Cache

IdentifierAcquisition

Duplicate Address Detection

AddressResolution

Configuration Process

t1p1

p0 t2 p3 t3

(Resource BatteryPower)

p5

(Resource Bandwidth PB)

p4

(Resource CPU PP)

p6

3


Duplicate Address Detection Address

Resolution

12

2

ConfiguredMobileAuthenticated

2

2

3

Sub-process - 1(Identifier Acquisition)

Client isin process of getting IP address

Initial Client SendsDiscoverMessage

ServerOffers Address

Client RequestsAddress

ServerAcknowledges

P1

P3

P4t1

t2 t3 t4

(Resource battery) (Resource Bandwidth)

(Resource Processing power)

p5p4 p6

P2

Client ischecking theaddress

Client Waits for theaddress

Sub-process - 2Duplicate Address Detection

Initial ClientSendsARP/NeighborDiscovery

Client confirmsthe address

P1P2 P3

t1t2 t3

Client Listen for ARP response

(Resource Battery Power)

(Resource PB) (Resource PP)

3 21

3 1

2

Sub-process 3- IP Address Resolution (IP Address-MAC mapping)

Idle SendARP Broadcast

P1t1

(Resource Battery) (Resource PB) (Resource PP)

3

32 2

MapsIP addressto MAC

P 2

Network Processing ARP

t2

Reachability Analysis(Configuration)

M0= [1003430]T

M1= [0102120]T

M2= [0010220]T

M3= [0003431]T

t1 fires

t2 fires

t3 fires

Incidence Matrix Analysis(Configuration)

Output matrix D+=

Input Matrix D- =

Incidence matrix D = D+ - D- =

Matrix equation-based approach(Configuration)

µ’ = µ+x.D

Given a sequence σ = t1t2t3 translates to a firing vector

f(σ) = (1,1,1), one can determine the marking µ’ as

µ’ = (1, 0,0,3,4,3,0) +(1,1,1).

µ’ = (1,0,0,3,4,3,0) + (-1,0,0,0,0,0,1)

µ’ = (0,0,0,3,4,31)

Thus, µ’ is reachable from the initial marking with a sequence of transition t1,t2,t3 that corresponds to (1,1,1)

t11

p1p0t2

p2

t13

DisconnectTrigger

ScanningL3 subnet discovery

Server discovery

(Resource PM) (Resource PB) (Resource PP)

2 1 2

32

Discovery Process

Resourcesdiscovered

p6

p3 p4 p5

Discovery Process

t1p1p0 t2 p2

t3

Layer 2association

Router Solicitation

Domainadvertisement

(Resource battery) (Resource PB) (Resource PP)

2

Network Attachment

Mobile connected

p6

p3 p4 p5

Channelavailable

Attachment Process

t1p1p0

t2

WEPKey

OpenAuth

EAP

p3p2

p4

2

2

Mobile Authenticated

p5

3

22

(Resource Battery PM)

(ResourceProcessing Power PP)


Authentication Process

Domaindiscovered

L3 subnet discovery

NetworkDiscovery

t1p0 t2 p4 t3

DisconnectTrigger

scanningServer discovery

NetworkAttachment

t5

t4p5

p7 t23

Probing

RouterSolicitation Domain

advertisement

t6p8 t7

Authentication

WEPKey Open

Auth

EAP

P2

P1

P3

p10

Channelavailable



AddressResolution

p12p11

t9p13

MobileConfigured

ServerDiscovered

Configuration

p6

p9

p14t8 t10

t11 p15

Discovery, Attachment, Authentication,Configuration,

L3 subnet discovery

NetworkDiscovery

t1p0 t2 p4 t3

DisconnectTrigger

scanningServer discovery

NetworkAttachment

t5

t4p5

p7 t23

Probing

RouterSolicitation Domain

advertisement

t6p8 t7

Authentication

WEPKey Open

Auth

EAP

P2

P1

P3

p10

Channelavailable



AddressResolution

p12p11

t9p13

MobileConfigured

ServerDiscovered

Domaindiscovered

Configuration

p6

p9

p14t8 t10

t11 p15

Layertransition

Location

Extraneous action

Layer 2

Layer 3

ApplicationLayer

Layer 2Event

Layer 3Event

Layer 4Event

Enter Mobility Event

Leave layer 2

Disconnected

Leave layer 3

Leave mobilityevent

Enter layer 3

Enter layer 2

Connected

SNR goes belowa threshold

State

Eventtransition

discovery

Scanning is performed

NetworkSelected

L2 authentication performed

Authenticated

L3 discovery

L3 addressacquisition

DAD

configuration

L3 authenticationperformed

authenticated

buffering

BU performed

Forwarding

Media redirection

Petri net model across layers (x)

System evaluation Experimental and model-based

Experimental systems based on optimization principles Proof-of-concept of Experimental Systems I have verified

Types

Of

scheduling

Relevant

Optimization

Principles

SIP-based

Fast handoff

Mobile

VPN

Media

Independent

Pre-authentication

Simultaneous

Mobility

Optimized handoff

In IMS

Muti-layer

Mobility

Fast

Handoff

For Multicast

Target

System

Sequential Maintain direct

path between CH and MH

xP

E

R

F

O

R

M

A

N

C

E

&

R

E

S

O

U

R

C

E

S

Limit binding update between CH and MH

x X

Maintain Security association

between end-points

X

Anchor-based

forwarding x X

Predictive Proactive network discovery XProactive authentication XProactive identifier configuration

X

Proactive

binding update x xDynamic Buffering xProactive Security association

(context transfer)

x

Parallel Simultaneous discovery of Layer 2 and

Layer 3 point of attachment

x

System Evaluation: Media Independent Pre-authentication – Architecture

AA CA

MN-CA keyAR

Network 3

AR

AA CA

MN-CA key

Network 2

INTERNETInformation

Server

Mobile

CurrentNetwork 1

AR

AP1 Coverage Area AP 2 & 3 Coverage Area

AR

Network 4

CN

AP3AP2AP1 CTNTN

CTN – Candidate Target NetworksTN – Target Network

Home Network HA

Media Independent Pre-authentication Mechanism

CN: Correspondent NodeMN: Mobile NodeAA: Authentication AgentCA: Configuration AgentAR: Access Router

AA CA

A(X)

2. DATA [CN<->A(Y)] over proactive handovertunnel [AR<->A(X)]

AR

L2 handoff procedure

Domain XDomain Y

CN

Data in new domain

1. DATA[CN<->A(X)]

MN-CA key

Preconfiguration

pre-authentication

MN-AR key3. DATA[CN<->A(Y)]

Data in old domain

MN

A(Y)

BU

Proactive handovertunneling end

procedure

Tunneled Data

MN

• Proactive discovery of networks and network elements• Proactive authentication• Pre-configuration by caching IP address• Proactive binding update• Buffering and copy-forwarding techniques

Key Optimization Techniques Applied:

InformationServer

Proactivediscovery

BufferModule

Experimental results Post-authentication vs. Pre-authenticationTypes

Of Authentication

Post-authentication

(Sequential)

Network Layer

Assisted layer 2

(Proactive discovery and Pre-authentication)

Handoff

Operation

Non

Roaming

Roaming Non

Roaming

Roaming

Tscan 460 ms 460 ms 0 0

Tauth 61 ms 599 ms 177 ms 831 ms

TConf

(2 AP)

0 0 16 ms 17 ms

Tassoc

+ 4 Way handshake

18 ms 17 ms 15 ms 17 ms

Total 539 ms 1076 ms 208 ms 865 ms

Time affecting handover

539 ms 1076 ms 15 ms 17 ms

Results (I) Proactive vs. non-optimized – Intra-technology

handoff802.11 802.11

• non-optimized– About 200 packets loss, ~ 4 s during

handover• Includes standard delay due to layer 2, IP

address acquisition, Re-Invite, Authentication/Authorization

• Media Independent Pre-auth – No packet loss during pre-authentication,

pre-configuration and pro-active handoff before L2 handoff

– Zero packet loss with buffering, 5 ms delay during handoff

• Includes delay due to layer 2, update to delete the tunnel on the router

• reduced the layer 2 delay in hostapDriver• L2 delay depends upon driver and chipset

Mobility Type MIPv6 SIP Mobility

Handoff

Parameters

Buffering Disabled

+ RO Disabled

Buffering

Enabled

+ RO

Disabled

Buffering Disabled

+ RO

Enabled

Buffering

Enabled

+ RO

Enabled

Buffering

Disabled

Buffering

Enabled

L2 handoff (ms)

4.00 4.0 4.00 4.00 4.00 4.00

L3 handoff

(ms)

1.00 1.00 1.00 1.00 1.00 1.00

Avg. packet loss

1.3 0 0.7 0 1.50 0

Avg. inter-packet interval (ms)

16.00 16.00 16.00 16.00 16.00 16.00

Avg. inter-packet arrival time during handover (ms)

21 45 21 67 21 29.00

Avg. packet jitter (ms)

n/a 29.00 n/a 51.00 n/a 13.00

Buffering period (ms)

n/a 50.00 n/a 50.00 n/a 20.00

Avg. Buffered Packets

n/a 2.00 n/a 3.00 n/a 3.00

Detailed Results: Proactive Handoff

802.11 802.114 s

MNMPA Client

MNMIHF

MPA Server

ParameterReport and Link Down

Subscription

Target Network: CDMA

13. Link Parameter Report Indication (Threshold 3)

4. Get Info Request

9. Get Info Confirm

1. Subscribe Request to event: Link Parameter Report

5. MIH Message: Get Info Request (SPRQL query) InformationService Query

Response

2. Configure Threshold Request: Wi-Fi Signal Levels: thr1, thr2, thr3

ISMIH User

MPA Proactive HO 12. MPA: Pre-authentication, Pre-configuration, Proactive HO Tunnel

ISMIHF

Mobile Node (MN)

Information Server

confirm

Link Going DownThreshold 1



11. Link Action Request: EV-DO, Link Power Up

confirm

14. MPA: Layer 2 HO

confirm



8. MIH Message: Get Info Response (RDF query response)

6. Get Info Request

7. Get Info Response

ThresholdConfiguration

MPA HO Complete

EV-DO Link Up

Legend

MIH Commands

MIH Link Events

MPA Signaling

Message Types

EV-DO interface

VoIP Through

Wi-Fi interface

15. Link Action Request: Wi-Fi, Link Power DownWi-Fi Link Down

confirm

Mobile Initiated Handoff – Heterogeneous handover

Wi-Fi Link Down

MNMPA Client

MNMIHF

Serving PoS: WiFi

11. Link Action Request: Wi-Fi, Link Power Down

4. Get Info Request (SPRQL query) Info Service

Query/Response

2. Configure Threshold Request: Wi-Fi Signal Levels: thr1

MPA Proactive HO 9. MPA: Pre-authentication, Pre-configuration, Proactive HO Tunnel

Mobile Node (MN)Information

Server

confirm

Link Going Down

6. Link Action Request: EV-DO, Link Power Up

Response

10. MPA: actual HO

3. Link Parameter Report Indication

5. Net HO Candidate Request

Get Info Response (RDF query response)

Link Parameter Rep Subscription &

ThresholdConfiguration

MPA HOComplete

EV-DO Link Up

MPA Server

Target PoS:CDMA

1. Subscribe Req.:Link Parameter Rep

Response

7.Response

Net HO CandidateIndication

Response

Response

8. N2N HO Query Resources Request

N2N HO Query Resources

Net HO Candidate Request

confirm

Net HO Candidate Response

Network Initiated Handoff – Heterogeneous handover

A. Comparison of optimized and non-optimized homogeneous handoff

Handoff Delay~ 18 s

802.11 CDMA

Handoff Delay16 s

802.11 CDMA

a. MIP-based Non-optimized handoff

b. SIP-based Non-optimized handoff

c. MPA and 802.21 assisted optimizedhandoff

802.11 CDMA

B. Comparison of optimized and non-optimized heterogeneous handoff

b. MPA assisted optimized handoff

a. Non-optimized handoff

Media interruption 4 s

802.11 802.11

MPA Server10.10.40.52/24

Sample Application: skype

Wifi AP MN

Pre-Auth

CN

Sample Application: skype

X.X.X.X/Y(Global IP)

Local IP0: 10.10.40.21

Internet

EV-DO Network

MN Traffic= IP-IP: X.X.X.X/10.10.40.21

TunnelBuffer

Provide handover services to MN via tunneled traffic

10.10.30.52/24

IS

802.21 capable device.

802.21 Info Server can be used in EV-DO

to WiFi Handover

MIH Query for WiFi access availability

MN Traffic= IP-IP: X.X.X.X/ Verizon PPP

Local IP1: Verizon PPP (via EV-DO)

AAA

nARL3 PoA

MN

AP1L2 PoA

AP0(L2 PoA)

Pre-authentication

Network ANetwork B

Pre-configuration

pARL3 PoA

CoreNetwork DHCP

server PANA server

Buffering module

Tunnelingmodule

MN

HA (MIP)Home Network

Proactive Handover Tunnel

CN

Network C Network D

802.11 – 802.11 802.11 – CDMA

Petri net model forSample Optimization Techniques

Results from Petri net modeling• Using MATLAB analyze Timed Petri net-based mobility

models and verify optimization techniques– Optimized security association– Hierarchical binding update– Redirection of in-flight data– Optimized configuration– Multi-interface mobility– Simultaneous mobility– Multicast mobility

• Prediction of handover performance under different handoff schedules– Sequential, parallel, proactive

• Verification of system behavior– Deadlocks in the system

• Concurrent system• Simultaneous mobility

VPN mobility (without HA) MNCN i-HA VPN-GW

data

Handoff

Tunnel1 Tunnel2

IKE Key exchange

Context establishment

Double tunneled data

New VPN tunnel creation

New data New data on double tunnel

Tunnel/Detunnel

VPN mobility with home agent (x-HA)

CN i-HA x-HAVPN-GW MN

HandoffX-MIP Reg

X-MIP reply

Tunnel1 Tunnel2 Tunnel3

Triple tunneled data

New MIPTunnel creation

Triple tunneled dataTunnel/de-tunnel

Mobile VPN resource analysisTasks Resources Needed

Battery

Power

Bandwidth Processing Power

VPN

Mobility

without

x-HA

IKE 2 3 1

Security context 1 1 2

New VPN Tunnel creation

1 1 2

Tunnel/de-tunnel ops 1 2 2

VPN mobility

with HA

External MIP update 1 1 1

New MIP Tunnel creation

1 1 1

Tunnel/de-tunnel ops 1 3 3

MobileGets data

Security Contextestablished

t1p1p0

t2

MobileRe-configured

IKEExchange

p4p3p5

2

p2

3

3

(Battery Power)(ResourceProcessing Power PP)


Tunnelcreation

Tunnel/De-tunneloperation

2

2

p6

VPN mobility (without HA)

New Tunnelcreation

t1p1p0

t2

Mobilere-configured

IdentifierUpdate

p4p3

p5

p5

(Battery Power) (ResourceProcessing Power PP)


MobileGets data

Tunnel/de-tunneloperations

p2

2

3

p6

VPN mobility (with xHA)

MH CHVisited SIP

RegistrarForwarding Agent

IP2(New Address)

Re-INVITE

Forward traffic

(IP1:p1 ---> IP2:p1)

New traffic from CH

SIP-CGI (3)

Media before handoff

(Binding Update)

Register (Fast Binding Update)

Tunneled in-flight data

ACK

OK

Handoff

Hierarchical binding update

Mobileconfigured

GlobalBindingUpdate

Identifier Verification

IdentifierMapping

FastBindingUpdate

Mobile getsTransient data

LocalTunnel setup

LocalForwarding

GlobalDataforwarding

Packet reordering

t1 t2 t3 t4

t5t6

t7

t8

p12p11

p13PBPM

3

PP

Petri net model: Hierarchical binding update

MN CNSA1 SA3MA1 HA

SA2 Adv

LCoA and RCoAConfiguration

Local Binding Update (LBU)

Local Binding Acknowledgement (LBacK)

Global BU

MN-MA Tunnel

SA3 Adv

Local Binding Update

LBacK

MN- MA Tunnel (New)l

Data

DataTunneled Data

Global ACK

MA2SA2

Inter-domainhandoff

Intra-domainhnadoffLCoA Configuration LBU

Data

Tunnel

Data

Hierarchical binding update

Localconfiguration

Globalconfiguration

MN-MATunnel creationLocal

Binding Update

GlobalBinding Update

MA-HATunnelcreation

HA-MA Tunneling

De-capsulation/Encapsulationat MA

MA-MN Tunneling

Mobileauthenticated

De-capsulation/Encapsulationat MA

Localconfiguration

MN-MATunnel creation

LocalBinding Update

MA Tunneling

De-capsulation/at the mobile

Mobileauthenticated

MobileReceives Data

a. Inter-domain handoff

b. Intra-domain handoff

Pteri net model: Hierarchical binding update

RA RouterDHCPServerMobile

NodeDHCP Discover

DHCP Offer

DHCP Request

DHCP ACK

Update ARPcacheMulticast announcement

Multicast announcement

MobileAssigns address

(a)

Duplicate Address Detection Optimization

DAD Optimization

MobileAuthenticated

Identifier Acquisition

P4 P5 P6

Addressresolution

Mobileconfigured


P0

P1

P2

P3Battery power

Bandwidth ProcessingPower

Multi-interface mobility

• Key Points to elaborate– Precedence relationship and resource constraints

affect the way handoff takes place between the access networks

– As an example, each access network has different characteristics and resource constraints

• CDMA network has bandwidth resource constraints• 802.11 network maybe limited to CPU power constraints• Authentication procedures is different in two different

networks– The model has the ability to predict the handoff

performance when the mobile hands off between two different access networks with certain resource constraints

Resource usage and timing operation (CDMA vs. 802.11)

Operations Resources in 802.11 Operations in CDMA Timing

Battery

Power

(nJ)

Bytes

transferred

CPU

(cycles)

Battery

Power

(nJ)

Bytes

transferred

CPU

Processing

(tokens)

802.11 CDMA

Discovery 414000 345 12 196800 328 9 745 422

Layer 2

Authentication

4126800 3439 29 1392000 232 14 106 200

Configuration 2257200 1881 22 5454000 909 12 510 850

Security

Association

940800 784 10 4752000 792 10 640 4500

Binding

Update

422400 352 18 2160000 360 18 168 599

Bandwidth Resource is different in 802.11 and CDMA(Mobile is connected when both are connected)

802.11 and CDMA interfaces come up in parallel(mobile is in connected state only when both the interfaces are

active)

802.11 and CDMA – parallel (If any one interface is active then the mobile is in connected state

802.11-CDMA – make-before-break

802.11 – CDMA Break-before-make

Coverability Tree

t1p1p0

t2 p2 t3

DisconnectTrigger

ScanningL3 subnet discovery Server

discovery

2 1 2

32

Resourcesdiscovered

p6

p3 p4 p5

(Resource: Battery power) (Resource: CPU cycles )(Resource: Bandwidth)

t1p1p0 t2 p2

t3

Layer 2association

Router Solicitation Domain

advertisement

2

Mobile connected

p6

p3 p4 p5

Channelavailable

(Resource: Battery Power) (Resource: CPU Cycles)(Resource: Bandwidth)

t1p1p0

t2

WEPKey

OpenAuth

EAP

p3p2

p4

2

2

Mobile Authenticated

p5

3

22

(Resource: Battery power) (Resource: CPU cycles)(Resource: Bandwidth)

t1p1

p0 t2 p2 t3

p4p3 p5

3

1



AddressResolution

12

2

MobileConfigured

MobileAuthenticated

(Resource: Battery Power) (Resource: CPU cycles)(Resource: Bandwidth)

p6

Scheduling(Sequential/Parallel/Proactive)

Power Resources

scanning Authentication 4-way Handshake

t2 t3 t4 t5P2 P3 P4

Association

Connected

MobileDisconnected

BandwidthResources

CPUresources

P1

PB

PM

PP

P0

t1Disconnection

NetworkDiscovered

Mobileauthenticated

1 token

Sequential Operations (Discovery and Authentication

MATLAB model for sequential operations

PA

CPU

MemoryPB

4-way handshakecompletet2

t3 t4

P2

P3

t1

Scanning

Authentication

NetworkDiscovered

4-wayHandshakeOperation

P1

ResourcesNetwork b/w

MobileAuthenticated

ConnectedAssociation

P0

P01

P02

2

2

ConcurrentOperations (Discovery and Authentication)

MATLAB modeling for concurrent operations

Verification from Petri Net modeling using Cycle Time-based approach

Optimization

Schedule

Relevant

loop in Petri Net

Di N

i

Max Di/Ni

Minimum

Cycle Time

Sequential p0t1p1t2p2t3p3t4p4t5p0

470 1 470

Concurrent p0t1p01t2p1t3p3t4p0

420 1 420

Proactive P1t1P2t4P3t5P1 17 1 17

Transition Operation Time

t1 Disconnection

Trigger

5 ms

t2 Scanning 400 ms

t3 Authentication 50 ms

t4 4-way handshake 10 ms

t5 Association 5 ms

Association

Networkdiscovery

P11

t11

PA2

4-way Handshake(SA)

t1

t4 t5

P2 P3

Connected

Disconnected

Pre-authentication

Current Network Target Network

PA1

PC

PB1

PD

t12

t13

APKey installation

P12

P1

Network discovery and authentication Process – Proactive Scheduling

Token loading matrixTransition Time matrix

Distance matrix S Matrix

Sequential operation (Flyod Algorithm)

Token loading matrix Transition Time matrix

Distance matrix S matrix

Proactive operation (Floyd algorithm)

Deadlock analysis for handoff events

• Verification allows one to find out – If any specific sequence of

transitions/operations lead to any deadlock– If one specific state during handoff operation is

attainable from any other state by following a specific sequence of transitions

– Whether the coverability tree is reversible• The system comes back to the original state

• Methodology– Reachability analysis– Incidence Matrix-based equations

Untimed Concurrent (Resource deadlock) – (MATLAB)

Deadlock avoidance for concurrent operations(by adding resources)

Simultaneous Mobility (No deadlock)

Simultaneous Mobility (Deadlock due to incomplete binding update)

Simultaneous Mobility (Deadlock avoidance)

(By use of retransmission techniques)

Conclusions• This thesis contributes to the general theory of optimized

handover – It addresses the need for a formal systems model that can

characterize a mobility event, associated optimization methodologies and can provide handoff performance predictions

• Developed Petri net models for handoff that can – analyze the behavioral properties (e.g., deadlock)– validate systems performance of any type of handoff optimization – define handoff schedule to obtain a specific systems performance

• Developed optimization techniques across several layers and verified these techniques by applying these to several experimental case studies

• Based on the results derived a set of fundamental principles of systems optimization for handoff that include protocol design methodologies and guidelines that will enable deployment of right set of mobility protocols and optimization techniques

Future Work• Current Petri net model can be enhanced to study

mobility in ad hoc networks• Enhancement to generate automatic schedule of

handoff operations given a set of resource constraints, performance objectives and dependence graph

• Ability to design a customized mobility protocol that will define its own set of elementary operations for each of the desired handoff functions

• Future models should consider resource utilization among the network components (e.g., Access point, router, server) in a distributed fashion

• I envision specification of the functional components of mobility protocols and tools that search for context specific optimizations, such as caching, proactive feature and cross layer techniques

Backup slides(detailed results, mechanisms etc.)

Handoff Statistics• Handoff rate depends upon the following parameters

– Average cell size– Mobile’s speed (e.g., vehicular, pedestrian)– Average call duration– Cell capacity

• Example

Micro-cellular campus environment: A user is subjected to 8 to 10 handoffs per day

Macro-cellular environment: A regular commuter in USA is subjected to an average of 2 to 6 handoffs per day

• Average one-way commute is 16 miles• Cell site coverage varies from 5 miles to 15 miles• In a heavily dense area cell sizes are small to accommodate capacity

• Percentage of Handoff related signaling– Handoff related signaling amounts to about 2% of the total data traffic that a user is subjected to– Average user spends 700 minutes/month for voice = 23 minutes/day = 13*60*23 kbits/day = 2 Mbytes/day– Data usage - 90 Mbytes/month = 3 Mbytes/day– Thus, total data and voice should be about 5 Mbytes– Handoff related signaling messages – 70 kbytes/per day (MIPv6) , 100 Kbytes/day SIP– Handoff related signaling amounts to about 2% of the total traffic

Timing sequence for MPA (proactive handoff)

R2MNCNDHCP

RTP

PANA DHCP

PANA (ACK)

SIP Re_INVITE (IP1)56.359

56.478

56.582

RTP (39835)

OK

ACK

56.722

12.498

12.504

12.509

HandoffDecision

PANA Trigger to delete tunnel

RTP (42568)

RTP (42569)12.51312.52912.593

RTP (42573)

IWCONFIG (IOCTL)

RTP (42574)

12.585

(12.600)JOIN

(19.610)JOIN (ACK)(Auth/Assoc, ifconfig, route,)

L2 handoff+ local L3Configuration

PANA Response

RTP (42577)

BU

12.674

MNNetwork 1

Network 2 Network 3

First packet in new network (non-tunneled)

12.613Lost packet (in the tunnel)

DHCP(IP1)

RTP

RTP

Tunnel Deletedin PAA

RTP

X

First Tunneled Data

NoPackets lostDuring BU

Tunnel Setup

Signal

RTP Data

Lost RTP Data

Tunneled packet

RTP (42570)

OK (tunneled)

RTP packetsSpaced ~16-20 ms

IP0

IP1

RTP (42575)X

X

Lost packet (in the tunnel)

Lost packet (in the tunnel) RTP (42576)12.633

12.653

Review of Research ProgressTime

Line

Work Progress

at the proposal

Status

at the defense

Identification of handoff components Completed Completed

Design and proof of concept mobility optimization for handoff components

Completed Completed

Systems prototype verification of optimization methodologies

Completed Completed

Initial IP-mobility systems modeling Completed Completed

July

2008

Complete the validation of up to 4 optimization techniques using Petri net models

Working Completed

September

2008

Develop methodology for minimizing handoff using Petri net

Working Completed

November

2008

Tradeoff design of proactive handoff scheme

Working Completed

December

2008

Thesis writing Completed

March 2009 Thesis defense Present

Mobility systems modeling using Timed Petri netProblem• Mechanisms and design principles for

optimized handover are poorly understood• No formal methodology to systematically

discover or evaluate mobility optimizationsApproach• Identification of the fundamental properties

that are rebound during handover event• Systematic analysis of the primitive

handover operations• Modeling of the handover process that

allows performance predictions to be made for both an un-optimized handover and for specific optimization techniques under systems resource constraints

Results• Timed Petri net-based mobility models for

handoff processes using MATLAB and Time Net Tools

• Verification of optimization techniques• Prediction of handover performance under

some resource constraints (e.g., battery, CPU and network bandwidth)



NetworkAttached

MobileConfigured


P1 P2 P3P0t2

t3

p01

p02

p03

t01


Subnet discovery

Serverdiscovery

P11 P12 P13

t11 t12 t13

NetworkDiscovered

p21

p22

p23

L2association

Routersolicitation

DomainAdvertisement

t22

t21

t23

t1



Addressresolution

PA

CPU

MemoryPB

4-way handshakecompletet2

t3 t4

P2

P3

t1

Scanning

Authentication

NetworkDiscovered

4-wayHandshakeOperation

P1

ResourcesNetwork b/w

MobileAuthenticated

ConnectedAssociation

P0

P01

P02

2

2

Figure 2: Concurrent handoff operations

Figure 1: Timed Petri net modeling for handoff

Resource Usage –Configuration

Functions Tasks Resources Needed (Equivalent Tokens)

Battery

Power

Bandwidth CPU

cycles

Configuration Identifier Acquisition 1 1 1

Duplicate Address

Detection

3 3 1

Address resolution 3 2 1

Relevant Petri net representation to capture handoff primitives

t1 t2b. Conflict

P1

p1

p2

p1

p2

p1

p2

t1

t2

t3

f. Confusion

P1 t1 t2 P3

a. Sequential

c. Concurrent

p1

p2

t1

t2

P3

e. Merging

p1

p2 p3

t1

t2

g. Mutual exclusiveh. Priority

Techniques appliedfor mobility modeling

t1

d. Data dependency

ConnectedP8

Disconnected

NetworkDiscovered

NetworkAttached

MobileConfigured

AuthenticatedSecurityAssociationEstablished

Updated

NetworkResourceDiscovery Network

SelectionDetectionProcess Configuration

Process

AuthenticationProcess

Binding Update

MediaForwarding

P1 P2 P3

P4P5P6

P0

t1

t2t3

t4

t5t6t7

P7

Intra-domainBinding update

t8t9BufferingRedirection

t0

p01

p02

p03

t01

t02t03

t013

t04

Security AssociationProcess

Modeling IP Mobility in Petri Net

Resource 1

Resource 2

Resource 3

Scanning

Subnet discovery

2

Data dependency analysis of handoff components Handoff Process Depends on data

from Set of Data it depends on

(Not a complete list)

P11 - Channel discovery P00 Channel broadcast

P12 – Subnet discovery P21,P22 L2 beacon ID, L 3 Router advertisement

P13 – Server discovery P12 Subnet address, Default router address

P21 – L2 association P11 Channel number, MAC address, Auth Key

P22 – Router Solicitation P21, P12 Layer 2 binding

P23 – Domain Advertisement P13 Server configuration, Router advertisement

P31 – Identifier Acquisition P23, P12 Default gateway, Subnet address, server address

P32 – Duplicate Address Detection P31 ARP, Layer 3 connectivity

P33 – Address Resolution P32, P31 New Identifier

P41 - Authentication P13, P22 Discovery of auth server

P42 – Key derivation P41 Availability of PMK, Layer 2 and Layer 3 association

P51 – Identifier update P31, P52 Layer 3 address, Verification of L3 address

P52 – Identifier verification -

P53 – Identifier mapping P51 HA, CN gets the new address (Identifier)

P54 – Binding Cache - Completion of identifier update

P61 – Tunneling P51 End-point addresses (router), identifier address

P62 - Forwarding P51, P53 New address of the mobile

P63 - Buffering P62, P51 New Identifier acquisition

P64 – Multicasting/bicasting P51 New identifier acquisition

Hierarchical Petri Net modeling using Timenet (Mobile IPv6) Discovery

AuthenticationSecurity Association

BindingUpdate

Configuration

MediaRe-routing

Why Petri net

• Petri nets can exactly model non-product form features such as priorities, synchronization, forking, blocking

• Can be used as both logical and quantitative models

• Forms the foundation for formal analysis models

• Strong analysis methods

Formal approach to mobility systems modeling

Problem:• Mechanisms and design

principles for optimized handover

are poorly understood• No formal methodology to

systematically discover or evaluate

mobility optimizations

Approach:• Framework or model that can

analyze the mobility event in a

systematic way, can verify and

predict the performance under

systems resource constraints

Formal approach to mobility systems modeling Problem• Mechanisms and design principles for

optimized handover are poorly understood• No formal methodology to systematically

discover or evaluate mobility optimizationsApproach• Identification of the fundamental properties

that are rebound during handover event• Systematic analysis of the primitive

handover operations• Modeling of the handover process that

allows performance predictions to be made for both an un-optimized handover and for specific optimization techniques under systems resource constraints

Results• Timed Petri net-based mobility models for

handoff processes using MATLAB and Time Net tools to

• Verification of these models • Prediction of handover performance under

specific resource constraints (e.g., battery, CPU and network bandwidth)



NetworkAttached

MobileConfigured


P1 P2 P3P0t2

t3

p01

p02

p03

t01


Subnet discovery

Serverdiscovery

P11 P12 P13

t11 t12 t13

NetworkDiscovered

p21

p22

p23

L2association

Routersolicitation

DomainAdvertisement

t22

t21

t23

t1



Addressresolution

Handover Scenarios

A-1 A-2

Inter-subnet

Intra-subnet

Intra-tech &Inter-domain

Intra-tech & Intra-domain

Inter-tech &Inter-domain

Inter-tech &Intra-domain

Intra-tech &Intra-domain

802.11 (provider X) to CDMA (provider X)

802.11 (provider X) to CDMA (provider Y)

802.11b (provider X) to 802.11n (provider X)

802.11b (provider X) to 802.11n (provider Y)

Inter-tech & Intra-domain802.11 (provider X) to

CDMA (provider X)

A-3 A-4

B-1

B-2

Mobility/Function

AccessType

Network Discovery

Resource Discovery

TriggeringTechnique

DetectionTechnique

Configuration

Key exchange/Authentication

Encryption BindingUpdate

MediaRerouting

CDMA1X-EVDO

EVDO PILOTChannel

SYNCChannel

Channel

Strength

RTC TMSI Diffie-Hellman/CAVE

AES MSC PDSN/MSC

802.11 CSMA/CA

Beacon11R

11R802.21

SNR atMobile

Scanning.ChannelNumber,SSID

SSID,Channel number

Layer 2 authenticate802.1XEAP

WEP/WPA802.11i

Associate IAPP

Functional characteristics between CDMA and 802.11 networks

How to make the model useful for a realistic deployment

• How do the resource constraints and access characteristics affect the handover behavior during handover between heterogeneous access networks

• Single interface case– Between 802.11 networks

• Break-before-make case• Using virtual interface

• Multiple interface case– Between 802.11 and CDMA network

• Two cases– Make-before-break– Break-before-make

MIH Users

MIH Function

Lower Layers

MIH Users

MIH Function

Lower Layers

Local Entity Remote Entity

Remote Command

MIH

Eve

ntLi

nk E

vent

Remote Event

Link

Com

man

d

Rem

ote

Link

Co

mm

and

Remote IS Query/Response

Rem

ote

IS

Que

ry/R

espo

nse

IS

Que

ry/R

espo

nse

Rem

ote

MIH

Eve

nt

MIH

Indi

catio

n

MIH

Com

man

d

Systems Optimization for Mobility Management

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