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USHA: A Practical Vertical Handoff Solution Ling-Jyh Chen, Tony Sun, Mario Gerla Computer Science Department, UCLA USHA: A Practical Vertical Handoff Solution Introduction The emerging network applications Wireless & Mobility Multiple network interfaces Mobility June 14, 2005 MSAN 2005 2 USHA: A Practical Vertical Handoff Solution Handoff 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) June 14, 2005 MSAN 2005 3 USHA: A Practical Vertical Handoff Solution Seamless Handoff Two goals: low latencies and few packet losses Related Work Network Upper Layer Approaches MIPv4, IPv6 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? June 14, 2005 MSAN 2005 4 USHA: A Practical Vertical Handoff Solution Universal Seamless Handoff Architecture USHA: a “simple” and “practical” handoff solution. Internet NAT Server All packets are encapsulated NAT server Handoff Server and transmitted using UDP IP el n Applications are bound Ttounthe n Handoff u ne tunnel T l P transparent to the handoff. Iand Mobility 802.11b June 14, 2005 GPRS MSAN 2005 5 USHA: A Practical Vertical Handoff Solution Experiment Scenario (1) Indoor mobility: Ethernet & 802.11b June 14, 2005 MSAN 2005 6 USHA: A Practical Vertical Handoff Solution Experiment (1): LOW_to_HIGH June 14, 2005 MSAN 2005 7 USHA: A Practical Vertical Handoff Solution Experiment (1): HIGH_to_LOW June 14, 2005 MSAN 2005 8 USHA: A Practical Vertical Handoff Solution Experiment Scenario (2) Outdoor mobility: 802.11b & 1xRTT June 14, 2005 MSAN 2005 9 USHA: A Practical Vertical Handoff Solution Experiment (2): LOW_to_HIGH June 14, 2005 MSAN 2005 10 USHA: A Practical Vertical Handoff Solution Experiment (2): HIGH_to_LOW June 14, 2005 MSAN 2005 11 USHA: A Practical Vertical Handoff Solution Handoff 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 June 14, 2005 MSAN 2005 12 USHA: A Practical Vertical Handoff Solution USHA extensions Detecting handoff events and performing service adaptation Handoff Server Transcoding according to available bandwidth and MH properties Traffic encryption Mobile Host June 14, 2005 IP l e n n Tu Internet Server Account management and access control Real-time compression Intelligent handoff: decide the “best” time and target interface to handoff MSAN 2005 13 USHA: A Practical Vertical Handoff Solution USHA extensions Examples: Traffic encryption: IPsec [6] Real-time compression: LZO [8] Intelligent handoff: Wang [18], Chen [ANWIRE’04] Service adaptation: Chen [QShine’05] June 14, 2005 MSAN 2005 14 USHA: A Practical Vertical Handoff Solution Some results of service adaptation Vertical Handoff from LOW_to_HIGH June 14, 2005 MSAN 2005 15 USHA: A Practical Vertical Handoff Solution Some results of service adaptation Vertical Handoff from HIGH_to_LOW June 14, 2005 MSAN 2005 16 USHA: A Practical Vertical Handoff Solution Conclusions 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. June 14, 2005 MSAN 2005 17 USHA: A Practical Vertical Handoff Solution Thanks! http://www.cs.ucla.edu/NRL June 14, 2005 MSAN 2005 18