USHA: A Practical Vertical Handoff Solution

USHA: A Practical USHA: A Practical Vertical Handoff SolutionVertical Handoff Solution

Ling-Jyh Chen, Tony Sun, Mario GerlaLing-Jyh Chen, Tony Sun, Mario Gerla

Computer Science Department, UCLAComputer Science Department, UCLA

MSAN 2005 2June 14, 2005

IntroductionIntroduction The emerging network applications

Wireless & Mobility Multiple network interfaces

MobilityMobility

USHA: A Practical Vertical Handoff SolutionUSHA: A Practical Vertical Handoff Solution

MSAN 2005 3June 14, 2005

HandoffHandoff

A seamlessseamless handoff is defined as a handoff scheme that maintains the connectivity of all applications on the mobile device when the handoff occurs.

ChallengesChallenges: maintaining application sessions (e.g. TCP)


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Seamless HandoffSeamless Handoff

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:Question: Which one are you using? Which one are you using?


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802.11b GPRS

HandoffServer

Handoff

Mobility

Internet

USHA: a “simple” and “practical” handoff solution.

NAT ServerAll packets are encapsulated and transmitted using UDP

All packets are encapsulated and transmitted using UDP

NAT serverNAT server

Applications are bound to the tunnel and transparent to the handoff.

Applications are bound to the tunnel and transparent to the handoff.

Universal Seamless Handoff ArchitectureUniversal Seamless Handoff Architecture


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Experiment Scenario (1)Experiment Scenario (1)

Indoor mobility: Ethernet & 802.11b


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Experiment (1): LOW_to_HIGHExperiment (1): LOW_to_HIGH


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Experiment (1): HIGH_to_LOWExperiment (1): HIGH_to_LOW


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Experiment Scenario (2)Experiment Scenario (2)

Outdoor mobility: 802.11b & 1xRTT


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Experiment (2): LOW_to_HIGHExperiment (2): LOW_to_HIGH


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Experiment (2): HIGH_to_LOWExperiment (2): HIGH_to_LOW


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Handoff Server SelectionHandoff Server Selection 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


MSAN 2005 13June 14, 2005

USHA extensionsUSHA extensions

Mobile Host

IP Tunnel

InternetServer

HandoffServer

Real-time compression

Intelligent handoff: decide the “best” time and target interface to handoff

Account management and access control

Traffic encryption

Detecting handoff events and performing service adaptation

Transcoding according to available bandwidth and MH properties


MSAN 2005 14June 14, 2005

USHA extensionsUSHA extensions

Examples:Traffic encryption: IPsec [6]Real-time compression: LZO [8] Intelligent handoff: Wang [18], Chen

[ANWIRE’04]Service adaptation: Chen [QShine’05]


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Some results of service adaptationSome results of service adaptation

Vertical Handoff from LOW_to_HIGH


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Some results of service adaptationSome results of service adaptation

Vertical Handoff from HIGH_to_LOW


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ConclusionsConclusions

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.


MSAN 2005 18June 14, 2005

Thanks!Thanks!

http://www.cs.ucla.edu/NRL


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USHA: A Practical Vertical Handoff Solution