USHA:%20A%20Practical%20Vertical%20Handoff%20Solution

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USHA A Practical Vertical Handoff Solution

• Ling-Jyh Chen, Tony Sun, Mario Gerla
• Computer Science Department, UCLA

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USHA A Practical Vertical Handoff Solution
Introduction

• The emerging network applications
• Wireless Mobility
• Multiple network interfaces

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Handoff
USHA A Practical Vertical Handoff Solution
A seamless handoff is defined as a handoff scheme
that maintains the connectivity of all
applications on the mobile device when the
handoff occurs.
Challenges maintaining application sessions
(e.g. TCP)
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Seamless Handoff
USHA A Practical Vertical Handoff Solution

• Two goals low latencies and few packet losses
• Related Work
• Network Layer Approaches
• MIPv4, IPv6
• Upper Layer Approaches
• End-to-End Approaches (e.g. Dynamic DNS)
• New Session Layer Protocols (e.g. MSOCKS)
• Transport Layer Protocols (e.g. TCP-MH and SCTP)
• Question Which one are you using?

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Universal Seamless Handoff Architecture
USHA A Practical Vertical Handoff Solution

• USHA a simple and practical handoff solution.

NAT server
NAT Server
All packets are encapsulated and transmitted
using UDP
Applications are bound to the tunnel and
transparent to the handoff.
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Experiment Scenario (1)
USHA A Practical Vertical Handoff Solution

• Indoor mobility Ethernet 802.11b

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Experiment (1) LOW_to_HIGH
USHA A Practical Vertical Handoff Solution
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Experiment (1) HIGH_to_LOW
USHA A Practical Vertical Handoff Solution
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Experiment Scenario (2)
USHA A Practical Vertical Handoff Solution

• Outdoor mobility 802.11b 1xRTT

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Experiment (2) LOW_to_HIGH
USHA A Practical Vertical Handoff Solution
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Experiment (2) HIGH_to_LOW
USHA A Practical Vertical Handoff Solution
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Handoff Server Selection
USHA A Practical Vertical Handoff Solution

• k network interfaces on the mobile host
• n available HS
• Di,j the round-trip delay from the i-th
  interface to the j-th handoff server
• Ci,j the capacity of the link from the i-th
  interface to the j-th handoff server

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USHA extensions
USHA A Practical Vertical Handoff Solution
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USHA extensions
USHA A Practical Vertical Handoff Solution

• Examples
• Traffic encryption IPsec 6
• Real-time compression LZO 8
• Intelligent handoff Wang 18, Chen ANWIRE04
• Service adaptation Chen QShine05

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Some results of service adaptation
USHA A Practical Vertical Handoff Solution

• Vertical Handoff from LOW_to_HIGH

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Some results of service adaptation
USHA A Practical Vertical Handoff Solution

• Vertical Handoff from HIGH_to_LOW

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Conclusions
USHA A Practical Vertical Handoff Solution

• We proposed a practical vertical handoff
  approach, called USHA.
• We evaluated USHA via a set of testbed
  experiments.
• Future Work
• Extending USHA to support more dynamic network
  scenarios (e.g. MANET), in which the vertical
  handoff may occur on application servers,
  clients, and/or intermediate hosts.

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USHA A Practical Vertical Handoff Solution

• Thanks!
• http//www.cs.ucla.edu/NRL