Mobility Management for Next Generation Wireless Internet
Ashutosh Dutta, Ph.D.Senior Scientist
NIKSUN Innovation CenterPrinceton
New Jersey, 08540
1
Email: [email protected]
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
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
[email protected]@subnet2.org
Registrar& proxy
[email protected]@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.