Transcript Seamless Vertical Handoff over Heterogeneous Network

An Agile Vertical Handoff
Scheme for Heterogeneous
Networks
Hsung-Pin Chang
Department of Computer Science
National Chung Hsing University
Taichung, Taiwan, R.O.C.
Outline
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Motivation
Related work

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Challenge and Contribution
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How to achieve seamless vertical handoff ?
How to pass NAT gateway ?
How to adapt TCP behavior ?
Experiments
Conclusion
Outline
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
Motivation
Related work


Challenge and Contribution



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How to achieve seamless vertical handoff ?
How to pass NAT gateway ?
How to adapt TCP behavior ?
Experiments
Conclusion
Hierarchical Overlay Network

Many different communications systems
coexist around us
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
Each owns different characteristics
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
Ethernet, Wireless LAN, GPRS, 3G…
Bandwidth, delay, cost……
Hierarchical overlay network

The combination of these heterogeneous
networks
Example: An Overlay Networks
Campus-wide (3G, GPRS)
Building-wide (WLAN)
Room-wide (Ethernet)
Horizontal versus Vertical Handoff
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Problem: handoffs
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Horizontal handoff
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The same kind of network technology
Ex: BSS to BSS
Vertical handoff
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<= what we are addressed
Different kinds of network technologies
Ex: Wireless LAN to 3G
Horizontal Handoff
BSS
BSS
AP
AP
Internet
Vertical Handoff
WCDMA
WLAN
AP
BS
Internet
Outline
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

Motivation
Related work: how to achieve seamless
vertical handoff ?
Challenge and Contribution




How to pass NAT gateway ?
How to adapt TCP behavior ?
Experiments
Conclusion
Previous Approaches to Vertical
Handoff 1/2
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Mobile IP/Infrastructure Based

Approaches
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Mobile IP with multicast



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Care-of-address is changed to a multicast address
Integration of WLAN and GPRS
Integration of WLAN and 3G
Problem

Require modification of network infrastructure


Hindrance to deployment
Need to be keep up to data

New technologies are always introduced
Previous Approaches to Vertical
Handoff 2/2
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End-to-end based
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Application layer
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
Transport layer: enable TCP connection alive even the
underlying IP address is changed
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
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SIP (Session Initiation Protocol)
TCP-R
TCP Migrate
Between transport layer and network layer
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C. Guo, et. al., “A Seamless and Proactive End-to-End Mobility
Solution for Roaming Across Heterogeneous Wireless
Networks,” IEEE JSAC, 22(5), pp.834-848. Jun. 2004
A Seamless and Proactive End-to-End Solutions for
Roaming Across Heterogeneous Wireless Networks
(1/4)
Network Applications
Socket Interface
Transport Layer
User
Kernel
BSD Sockets
TCP
UDP
LCT Table Translation
IP
Network Layer
Network Devices
PPP
SLIP
Ethernet
A Seamless and Proactive End-to-End Solutions for
Roaming Across Heterogeneous Wireless Networks (2/4)
B
A
Original
address
Original
port
Mapped
address
Mapped
port
A
p1
C
A
p2
p1
L
A
N
Original
port
Mapped
address
Mapped
port
A
p1
C
A
p2
p1
…
C
Original
address
W
L
A
N
Mobile Client
L
A
N
Fixed Host
A Seamless and Proactive End-to-End Solutions for
Roaming Across Heterogeneous Wireless Networks
(3/4)
Application
Application
A B
A B
Kernel
Kernel
Handoff Layer
Handoff Layer
Table Lookup
C B
圖3 封包表頭替換過程
Table Lookup
A Seamless and Proactive End-to-End Solutions for
Roaming Across Heterogeneous Wireless Networks
(4/4)
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Problems
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NAT issue
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
Require an S/N (Subscription/Notification) Server
Modify the infrastructure
TCP performance
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Do not consider
Outline
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
Motivation
Related work: how to achieve seamless
vertical handoff ?
Challenge and Contribution




How to pass NAT gateway ?
How to adapt TCP behavior ?
Experiments
Conclusion
How to pass NAT gateway ?

Problem


Communication must always be initiated by the
private network
Solution

Use the previous IP address as the source IP
address
Fixed Host
Problem
New IP address
NAT
Switch
WLAN
AP
Update
Ethernet
Fixed Host
Solution
Old IP address
NAT
Switch
WLAN
AP
Update
Ethernet
Outline
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Motivation
Related work: how to achieve seamless vertical
handoff ?
Challenge and Contribution
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How to pass NAT gateway ?
How to adapt TCP behavior ? => CWND-Restore
Experiments
Conclusion
How to adapt TCP behavior ?
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Problem
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TCP consider packet loss as network congestion
Slow down…
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But…now packet lose is because “handoff”
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Solution
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CWND-Restore
CWND-Restore
Fixed Host
CWND 50
20
2
NAT
Switch
Ethernet
WLAN
AP
Outline
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

Motivation
Related work: how to achieve seamless
vertical handoff ?
Challenge and Contribution




How to pass NAT gateway ?
How to adapt TCP behavior ?
Experiments
Conclusion
System Implementation- Linux Kernel
2.6.11
Applications
User Mode
Kernel Mode
TCP
UDP
CWND-restore
Connection Manager
Handoff Detection
IP
Ethernet
Driver
WLAN
Driver
3G
Experimental Platform
Fixed Host
Mobile Host
CPU
AMD XP 2600+
Intel Pentium M 1.4GHz
RAM
512 MB
256 MB
NIC #1
100Mbps Ethernet
100Mbps Fast Ethernet
Ethernet
NIC #2
Philips 802.11g WLAN
miniPCI Adapter
NIC #3
Novatel UMTS/WCDMA
USB Adapter
Experiment 2/2
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Experiments

TCP handoff verification

Handoff latency

TCP handoff performance

UDP handoff verification
Experiment 2/2
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Experiments

TCP handoff verification

Handoff latency

TCP handoff performance

UDP handoff verification
TCP Handoff Verification 1/7
Internet
NAT
Switch
BS
NAT
AP
C
Fixed Host
Mobile Host
B
Ethernet
A
WCDMA
WLAN
Experiment environment
TCP Handoff Verification 2/7

LAN to WLAN
11000
"LAN"
"WLAN"
10000
Sequence Number (KB)
9000
Handoff
8000
7000
6000
5000
4000
3000
2000
1000
0
0
1
2
3
4
5
Time (sec)
6
7
8
9
10
TCP Handoff Verification 3/7
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WLAN to LAN
11000
"LAN"
"WLAN"
Sequence Number (KB)
10000
9000
8000
7000
Handoff
6000
5000
4000
3000
2000
3
3.5
4
Time (sec)
4.5
5
TCP Handoff Verification 4/7
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LAN to WCDMA
6000
"LAN"
"WCDMA"
Handoff
Sequence Number (KB)
5000
4000
3000
2000
1000
0
0
50
100
Time (sec)
150
200
TCP Handoff Verification 5/7

WCDMA to LAN
6000
"LAN"
"WCDMA"
Sequence Number (KB)
5000
4000
Handoff
3000
2000
1000
0
0
50
100
150
Time (sec)
200
250
TCP Handoff Verification 6/7
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WLAN to WCDMA
6000
"WLAN"
"WCDMA"
Sequence Number (KB)
5000
Handoff
4000
3000
2000
1000
0
0
50
100
150
Time (sec)
200
250
TCP Handoff Verification 7/7

WCDMA to WLAN
6000
"WLAN"
"WCDMA"
Sequence Number (KB)
5000
4000
Handoff
3000
2000
1000
0
0
50
100
150
Time (sec)
200
250
Experiment 2/2

Experiments

TCP handoff verification

Handoff latency

TCP handoff performance
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UDP handoff verification
Handoff Latency 1/2
Internet
Switch
NAT
BS
Mobile Host
AP
Fixed Host
B
A
Ethernet
WLAN
Experiment environment
C
WCDMA
Handoff Latency 2/2
Handoff Latency (ms)
LAN to WLAN
LAN to WCDMA
WLAN to LAN
WLAN to WCDMA
3
438
1
503
WCDMA to LAN
1
WCDMA to WLAN
3
Experiment 2/2

Experiments

TCP handoff verification

Handoff latency

TCP handoff performance

UDP handoff verification
TCP Handoff Performance 1/8
Internet
Switch
NAT
BS
Mobile Host
AP
Fixed Host
B
A
Ethernet
WLAN
Experiment environment
C
WCDMA
TCP Handoff Performance 2/8
Original (KB/s)
CWND Freeze (KB/s)
WLAN to LAN
6154.8
7690.84
LAN to WLAN
177.58
244.87
WCDMA to LAN
2886.36
5059.62
WCDMA to WLAN
138.34
237.77
LAN to WCDMA
3.64
3.98
WLAN to WCDMA
3.47
4.12
TCP handoff performance 3/8

LAN to WLAN
100
"Original"
"CWND Freeze"
90
Handoff
Congestion Windows
80
70
60
50
40
30
20
10
0
9
9.5
10
Time (sec)
10.5
11
TCP handoff performance 4/8

WLAN to LAN
Handoff
100
"Original"
"CWND Freeze"
90
Congestion Windows
80
70
60
50
40
30
20
10
0
9
9.5
10
Time (sec)
10.5
11
TCP handoff performance 5/8

LAN to WCDMA
100
"Original"
"CWND Freeze"
90
Congestion Windows
80
70
60
Handoff
50
40
30
20
10
0
8
8.5
9
9.5
10
Time (sec)
10.5
11
11.5
12
TCP handoff performance 6/8

WCDMA to LAN Handoff
100
"Original"
"CWND Freeze"
90
Congestion Windows
80
70
60
50
40
30
20
10
0
9
9.5
10
Time (sec)
10.5
11
TCP handoff performance 7/8

WCDMA to WLAN
100
"Original"
"CWND Freeze"
90
Handoff
Congestion Windows
80
70
60
50
40
30
20
10
0
9
9.5
10
Time (sec)
10.5
11
TCP handoff performance 8/8

WLAN to WCDMA
100
"Original"
"CWND Freeze"
90
Handoff
Congestion Windows
80
70
60
50
40
30
20
10
0
9
9.5
10
Time (sec)
10.5
11
Experiment 2/2

Experiments

TCP handoff verification

Handoff latency

TCP handoff performance

UDP handoff verification
UDP Handoff Verification 1/3

Experiment environment
Internet
Switch
2. LAN
FH
AP
1. WLAN
MH
UDP Handoff Verification 1/3
Internet
Switch
AP
Mobile Host
B
A
WLAN
Fixed Host
Ethernet
WLAN
UDP Handoff Verification 2/3

LAN to WLAN
Sequence Number (KB)
25
"LAN"
"WLAN"
Handoff
20
15
10
5
0
0
2
4
6
8
10
Time (sec)
12
14
16
18
20
UDP Handoff Verification 3/3

WLAN to LAN
25
"LAN"
"WLAN"
Sequence Number (KB)
Handoff
20
15
10
5
0
0
2
4
6
8
10
Time (sec)
12
14
16
18
20
Outline

Introduction



Challenge






Hierarchy Overlay Network
Horizontal v.s. Vertical Handoff
How to achieve seamless vertical handoff ?
How to pass NAT gateway ?
How to adapt TCP behavior ?
How to adapt application behavior ?
Experiments
Conclusion
Conclusion

A Vertical Handoff framework

Support NAT while follows the end-to-end discipline


Without an modification to infrastructure
Improve TCP performance


CWND Freeze
At most 2.3 times the original TCP