Mobility Management for Next Generation Wireless Internet

Ashutosh Dutta, Ph.D.Senior Scientist

NIKSUN Innovation CenterPrinceton

New Jersey, 08540

1

Email: adutta@niksun.com

Outline

• Evolution of mobility protocols

• A taxonomy of IP-based mobility protocols

• Handoff optimization – Use Case studies

• Best Current Practices– Mobility Modeling, Applicability

• Conclusions/Future Work

.2

– A name identifies what you want,

– An address identifies where it is,

and– An route identifies a way to get there

John Shoch, 1978

42 Mb/s (DL),22 Mb/s (UL)

CDMA2000NX

TACS

NMT

AMPS

SMR

GPRS EDGEGSM

IS-136

IS-95 (A)

iDEN

PDC

IS-95 (B)CDMA2000

1X

WCDMA

1 G 2 G 2.5 G 3 G 4 G

144 kb/s, 384 kb/s, 2 Mb/s

144 kb/s, 384 kb/s, 2 Mb/s

JTACS

54 kb/s 236 kb/s

144 kb/s

50 UL, 100 DL

9.6 kb/s

9.6 kb/s

48.6 kb/s

42 kb/sNTT

24 kb/s

IEEE 802.16

802.20

EHSPA

UMB

LTE

80 Mb/s (UL), 360 Mb

280 Mb/s

80 Mb/s

115 kb/s

1980 1990 1995 2000 2008

Evolution of mobility protocols

Cellular Access CharacteristicsGeneration System Channel

spacing Access type Uplink data

rate 1G AMPS 30 kHz FDMA N/A

TACS 25 kHz FDMA N/A NMT 25 kHz FDMA N/A NTT 25 kHz FDMA N/A

2G GSM 200 kHz TDMA 9.6 kb/s PDC 30 kHz TDMA 42 kb/s IS-136 30 kHz F/TDMA 48 kb/s IS-95 (A) 1.25 MHz F/CDMA 14.4 kb/s iDEN 25 kHz F/TDMA 24 kb/s

2.5G GPRS 200 kHz TDMA 45 kb/s EDGE 200 kHZ TDMA 236 kb/s IS-95 (B) 1.25 MHz F/CDMA 115 kb/s CDMA2000 1X 1.25 MHz CDMA 144 kb/s

3G UMTS/WCDMA

5 MHz CDMA/TDMA

2 Mb/s

CDMA2000 1xEV-DO

1.25 MHz CDMA 2 Mb/s

4G LTE 20 MHz OFDMA 50 Mb/s WiMAX 2.5 GHz OFDM 40 Mb/s UMB 5 MHz OFDMA 75 Mb/s

MH

nPoAoPoABTS A

MSC

BSC 1

Serving Cell

BSC 2

Target Cell

VLRAUC

Move

EIR

BSS

nPoA nPoA

HLR

Cellular mobility – GSM – an example

BTS B BTS CBTS D

HLR – Home Location RegisterMSC - Mobile Switching Center

AUC – Authentication CenterBSC – Base Station ControllerBSS – Base Station SystemBTS – Base Transceiver StationEIR – Equipment Identity Register

VLR – Visitor Location Register

Home Agent

BSC1 BSC2 BSC3 BSC4

PCF1 PCF3 PCF4

PDSN2PDSN1

PCF2

FA1FA2

MSC

PSTN

GMSC

HLR

AC

A B CD F

BTS1

E

L3 PoA L3 PoA

L2 PoA BTS3 L2 PoA

VLR

CDMA2000 – An example

SourceeNB

TargeteNB

CandidateeNB

MME

Serving Gateway(S-GW)

PDN-GW

UE UE UE

SGSN

E-UTRAN

IP-basedIMS

network

Enhanced Packet Core (EPC)

UEUE

ePDG

UntrustedNon-3GPP

TrustedNon-3GPP(WiFI, WiMAX)

UTRAN

SAE/LTE - 4G Network

HSSPCRF

SGiS5

S11

S1-U

S1-MME

S4

S7

S6a

S3

S2a

S2b

AAA

S6c

Wm

Wn

PCEP

Rx+

Wx

S10

X2

X2 X2

What are Characteristics of Next Generation Networks?

• Heterogeneous networks (CDMA, LTE, WiMAX, 802.11)

–Access-independent converged IP network

• Order-of-magnitude increases in bandwidth

–MIMO, smart antennas

–Increase in video and other high bandwidth traffic

• New services and service enabling platforms (e.g., Web 2.0, SON)

• Large range of cell sizes, coverage areas

–PAN, LAN, WAN

–Pico-cellular, micro-cellular, cellular

• Changes in traffic and traffic patterns

–Rise in video on demand? Requires good high-bandwidth multicast

Mobile Wireless Internet: A Scenario

802.11a/b/g

BluetoothIPv6Network

UMTS/CDMANetwork

InternetDomain1Domain2

UMTS/CDMA

PSTN gateway

Hotspot

CHRoaming User Ad Hoc

Network

PAN

LAN

WAN

WAN

LAN

PSTN

802.11 a/b/g

Key Functions Characteristics

Handoff • May take place between cell, subnet or domain• Need to optimize the handoff delay and transient data loss ( e.g., end-to-delay up to 200 ms, 3%-5% packet loss, jitter, for real-time VoIP traffic)• May use soft-handoff feature of CDMA, but need fast-handoff mechanisms for other technologies (e.g., 802.11)• Need to support session based applications for TCP and RTP traffic

Configuration •Should be configured within few milliseconds•Configures IP address and other server parameters (e.g, DNS, SIP server, Gateway)

Registration • Assist pre-session mobility• Hierarchical nature will make the registration faster• Helps location management functionality

Quality of Service

•Need to maintain same QoS during its subnet/domain movement

Location Management

•Allow user to maintain same URI irrespective of point of attachment

Technical issues for mobility management

Mobility TaxonomyIP Mobility

Personal Terminal Service

ApplicationLayer

NetworkLayer

Session

• Systems Optimization

MIPv4 Cellular IPHAWAIIIDMP MIP-LR MIPV6ProxyMIPv6

SIPMMMIP-LR(M)Proxy

TransportLayer

MSOCKS, MigratemSCTP

Shim Layer

HIP

Issues

• Host controlledvs.

Mobile Controlled

• Mobility pattern

Backbone

AdministrativeDomain B

L2 PoA

CorrespondingHost

128.59.10.7

IPch

207.3.232.10

210.5.240.10

128.59.11.8

N2N1N1

N2

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

ConfigurationAgent

L3 PoA207.3.232.10

MobileHost

AuthenticationAgent

Authorization Agent

RegistrationAgent

RegistrationAgent

Administrative Domain A

ConfigurationAgent

Authorization Agent

SignalingProxy

AuthenticationAgent

SignalingProxy

Layer 3 PoA

L2 PoA Layer 2 PoA

Layer 2 PoA

L3 PoA

Mobility Illustration in a sample IP-based network

128.59.9.6

L3 PoA

A

B

CD

900 ms media interruption

802.11 802.11

h/o delay900 ms

802.11 802.11

4 Seconds media interruption h/o delay 4 s18 Seconds media interruptionh/o delay18 s

13

HandoverEvent

Network discovery &selection

Networkattachment

Configuration Securityassociation

Bindingupdate

Mediareroute

Channeldiscovery L2

association

Routersolicitation

DomainAdvertisement

Identifieracquisition

DuplicateAddressDetection

AddressResolution

Authentication(L2 and L3)

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

14

Handover: Distributed operation across multiple layers

Time

L2PoA

L3PoA

Discovery Detection 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

Layer 2 Handoff Delay (802.11)

• Discovery Phase

– Active scanning

• MN probes AP

– Passive scanning

• AP sends beacons periodically

• Authentication Phase

– Open authentication

– Shared authentication

– 802.11i – 4 way handshake

• Association Phase

Station performing handoff All APs withinrange on all channels

MN

Probe Request

Probe Response

(broadcast)

New AP

Reassociation Request

De-authentication

AuthenticationRequest

AuthenticationResponse

Re-associationRequest

Re-associationRequest

Re-associationResponse

Probe Delay

De-

auth

entic

atio

nD

elay

AuthenticationDelay

Re-associationDelay

Chan 1

Chan N

Layer 2 Discovery Optimization

General techniques:• Reduce the scanning time• Caching of ESSID• Use of second interface• 802.11 specific discovery• Proactive Discovery

– (no scanning)

Proposed Solutions:• Shin et al introduces selective

scanning and caching strategy• Montavont et al propose periodic

scanning• Velayos et al propose reduction of

beacon interval and performs search in parallel with data transmission

• Brik et al propose to use a second interface to scan while communicating with the first interface

• 802.11u, 802.11k• Forte and Schulzrinne• Application Layer proactive

discovery (e.g., Dutta et al)

Optimization techniques for layer 3 configuration

• Layer 3 address acquisition– Proactive caching

• Duplicate Address Detection– Optimistic DAD,

Proactive DAD, Passive DAD,

– Router Assisted DAD• NUD (Neighbor

Unreachability Detection)– Aggressive Router

Selection

Configuration

IdentifierAcquisition

DuplicateAddressVerification

IdentifierMapping

Layer 2

Layer 3

MobileNode

Server Network

MobileNode L3 POA Network

MNServerL3PoA

Configuration

IdentifierAcquisition

DuplicateAddressVerification

IdentifierMapping

Layer 2

Layer 3

MobileNode

Server Network

MobileNode L3 POA Network

MNServerL3PoA

Security Optimization• Security protocols have an impact on

the performances of the network

– End-to-end latency

– Throughput

– Handoff delay

• Main components that affect the performance

– Authentication/authorization, Key Derivation, Encryption

• Security related delays may affect allthe layers

• Layer 2 (e.g., 802.11i, WEP)

• Layer 3 (IPSEC/IKE)

• Upper Layers (e.g., TLS, SRTP)

Security Association

KeyDistribution Authentication Encryption

Layer 2

Layer 3

Layer 4

ServerMobile Network

MN

MN Server

L3POA

Security Association

KeyDistribution Authentication Encryption

Layer 2

Layer 3

Layer 4

ServerMobile Network

MN

MN Server

L3POA

Optimizing Binding Update• Techniques

– Reduce the latency due to longer binding update when the communicating host is far away

– Limit the binding update within a domain

• Proposed Solutions– IDMP– Regional registration-based

Mobile IP– HMIPv6– Anchor-based Application Layer

• B2BUA– Proactive Binding Update

Binding Update

Tunneling Mapping Caching

Mobile Network Anchor Mobile CN

AnchorPoint

CN

Binding Update

Tunneling Mapping Caching

Mobile Network AnchorMobile Network Anchor Mobile CN

AnchorPoint

CN

Use Case: Cross layer and multiple interfaces

Network Type

SSID/ Cell ID

BSSID

Operator

Security

NW

Channel

QoS

Physical Layer

Data

Rate

GSM

13989

N/A

AT&T

NA NA 1900

N/A

N/A 9.6 kbps

802.16d

NA

NA

T-Mobile

PKM

EAP-PEA

P

11

Yes

OFDM

40 Mbp

s

Wakeup WLANDownload over WLANShutdown GPS

Café

Airport

Zone 1 Zone 2 Zone 3

Zone 4 Zone 5 Zone 6

Zone 7 Zone 9

Wi-Fi

Wi-MAX

WLAN Link Going Down.

Switch to WiMAXDownload over WiMAXShutdown WLANWakeup GPS Zone 8

Wi-Fi

Connect to WLAN

Battery level lowShutdown WiMAXDownload over GSM/GPRS

Wakeup WLAN

Wi-MAX

Shutdown GPSStart Download over WLAN

Network Type

SSID/ Cell ID

BSSID Operator Security NW Channel QoS Physical Layer

Data Rate

GSM 13989 N/A AT&T NA NA 1900 N/A N/A 9.6 kbps

Network Type

SSID/ Cell ID

BSSID Operator Security NW Channel QoS Physical Layer

Data Rate

GSM 13989 N/A AT&T NA NA 1900 N/A N/A 9.6 kbps

802.11b Café 00:00:… Café .11i EAP-PEAP

6 .11e OFDM 11 Mbps

Network Type

SSID/ Cell ID

BSSID Operator Security EAP Type

Channel QoS Physical Layer

Data Rate

GSM 13989 N/A AT&T NA NA 1900 N/A N/A 9.6 Kbps

802.11b Airport 00:00:… Airport .11i EAP-PEAP

6 .11e OFDM 11 Mbps

Radio State

GSM

WLAN

WiMAX

GPS

Radio State

GSM

WLAN

WiMAX

GPS

Radio State

GSM

WLAN

WiMAX

GPS

Radio State

GSM

WLAN

WiMAX

GPS

Radio State

GSM

WLAN

WiMAX

GPS

Radio State

GSM

WLAN

WiMAX

GPS

Radio State

GSM

WLAN

WiMAX

GPS

IEEE 802.21 and MP Enabled Seamless Mobility Deployment Scenario

Courtesy: IEEE 802.21 chair

22

PDSN

S-CSCF

PDSN

AP

FTTH/ADSL

SIP AS

I-CSCF

MN

RAN RAN

IMS/MMD

cdma2000

HSS

P-CSCF P-CSCF

P-CSCF

non-SIP AS

non SIP

PCRFPCRF

PCRF

DifferentDomain DHCP

DHCPDHCP

Handoff Optimization in IMS/MMD Network

cdma2000

E-CSCF※

Optimized roaming

architecture

Non-SIP support

AAA/HSS Optimization

AAA

HA

P-CSCF Fast handoff

Copyright © 2007 Telcordia Technologies. All Rights Reserved.23

P-CSCF Fast-handoff Experimental Results

Figure 1: Levels of MMD Optimization

Components Optimized

0 3000 6000 9000 12000

Proactive

Reactive

Non-Optimized

Type

s of

Han

doff

Time in ms

PPP TerminationLayer 2 DelayPPP ActivationMIP-SolicitationMIP-Binding UpdateDHCP TriggerDHCP InformSIP TriggerSIP+SecurityMedia Redirection

Components Optimized

Media Independent Pre-authentication - Seamless Handoff (a deployment scenario)

AA CA

MN-CA keyAR

Network 3

AR

AA CA

MN-CA keyNetwork 2

INTERNETInformation

Server

Mobile

CurrentNetwork 1

AR

AP1 Coverage Area AP 2 & 3 Coverage Area

ARNetwork 4

CN

AP3AP2AP1 CTNTN

CTN – Candidate Target NetworksTN – Target Network

Performance (MPA-Non-MPA) – Single I/F• MPA

– No packet loss during pre-authentication, pre-configuration and pro-active handoff before L2 handoff

– Only 0 packet loss, 4 ms delay during handoff mostly transient data

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

• We also reduced the layer 2 delay in hostap

Driver• L2 delay depends upon driver and

chipset

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

handover• Includes standard delay due to layer 2,

IP address acquisition, Re-Invite, Authentication/Authorization

– Could be more if we have firewalls also set up

MPA Approach

Non-MPA Approach

handoff802.11 802.11

4 s

a. MIP-based Non-optimized handoff

b. SIP-based Non-optimized handoff

c. MPA and 802.21 assisted optimizedhandoff

Optimized handoff delay with MPA (Multiple I/F)

27

Schedulingof handoveroperations

Relevantoptimizationprinciples

Example experimental mobility systems PotentialTargetMobilitySystem

SIP-basedFast handoff

MobileVPN

MediaIndependentPre-authentication

Simultaneous Mobility

Optimized handoffIn IMS

Muti-layerMobility

Multicast fast handoff

Sequential Direct path between CH and MH XLimit binding update between CH and MH X X

Maintain Security associationbetween end-points

X

Anchor-basedForwarding

X X

Post-handoff triggers X

Proactive Pre-handoff triggers X X

Proactive network discovery XProactive authentication XProactive identifier configuration X

Proactivebinding update

X X

Dynamic Buffering XProactive context transfer X

Parallel Discovery of Layer 2 and Layer 3 PoA X

Binding update X

Optimal mobility system design

Dependency analysis among handover operationsHandoff 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 28

Resource usage per mobility eventsSub transitions

Sub-operations Resource Consumption

Bytes exchanged CPU samples Power due to transmission(nanojoules)

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 23040029

Modeling of handoff processes – An example

P00 t01

t11

t41

p11

p41

t13

p13t42

p42

t21

p21

t22

p22

t12

p12

t23

p23 P52

t52 t51 P51

t53 p53

t64p64

t62

p62

t63

p63

t54 p54

p61

t31 t32 t33

p31 p32 p33

t70

Resource network capacity

Resource Battery

Resource CPU

PotentialParallelOperation

Connected

Conclusions/Future Work • 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

• Need to define mobility model that will allow to predict the handoff performance and behavioral characteristics such as deadlock based on mobility patterns

• Define Best Current Practices for Mobility Management for IP-based handoff

• Several Applications– Mobile Cloud Computing, Roaming among carriers, End-to-end QoS

31

Several concepts of mobility• Terminal mobility, e.g., supported by Mobile IP

IP-based NetworkCH

Subnet 1MH

Subnet 2

IP-based Network

CH

Subnet 1

MH

Subnet 2• Typically, you don’t just have terminals– Users/Persons

– Sessions

• Mobility of users, sessions?

Personal Mobility: Registration

IP-based Network

CH

Subnet 1

Subnet 2

registrar

IP-based Network

CH

Subnet 1

Subnet 2

registrar

• When lady in red moves, she

– leaves her laptop behind

– Uses another machine

– Logs in

• User registration performed

person@subnet1.org

person@subnet2.org

Personal Mobility: simultaneous registration of multiple bindings

IP-based Network

CH

Subnet 1

Subnet 2

Registrar& proxy

IP-based Network

CH

Subnet 1

Subnet 2• When lady in red moves, she

– leaves her laptop behind

– Uses another machine

• She can still be located

person@subnet1.orgperson@subnet2.org

Registrar& proxy

person@subnet1.orgperson@subnet2.org

Session Mobility

IP-based Network

CH

Subnet 1

MH

Subnet 2

IP-based Network

CH

Subnet 1

Subnet 2

INVITE 2

3

1

Service Mobility• Service Mobility allows a roaming user to get the same view of

the network as when he is at home

• At the time of registration

–User’s service profile is retrieved from the home network

–The service profile is shared with the responsible entity at home and in the foreign network (wholly or partially)

• The foreign network provides some of the service required

• The home network still retains responsibility for other services

• Examples of entries in the profile of interest may be address book, call handling features, buddy lists, etc.