1 / 19

Enhancing QoS Support for Vertical Handoffs Using Implicit/Explicit Handoff Notifications

Enhancing QoS Support for Vertical Handoffs Using Implicit/Explicit Handoff Notifications. Ling-Jyh Chen, Guang Yang, Tony Sun, M. Y. Sanadidi and Mario Gerla Computer Science Department University of California, Los Angeles. QoS Enhancement for Vertical Handoffs.

kolton
Download Presentation

Enhancing QoS Support for Vertical Handoffs Using Implicit/Explicit Handoff Notifications

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Enhancing QoS Support forVertical Handoffs Using Implicit/Explicit Handoff Notifications Ling-Jyh Chen, Guang Yang, Tony Sun,M. Y. Sanadidi and Mario Gerla Computer Science DepartmentUniversity of California, Los Angeles QShine 2005, Orlando, Florida

  2. QoS Enhancement for Vertical Handoffs • Goal: Providing highly agile system for mobile applications. QShine 2005, Orlando, Florida

  3. Related Work • Conventional adaptive method: AIMD • TCP, RAP, … • TEAR, TFRC, … • They DO NOT perform well in vertical handoffs[Gurtov et al, MC2R ’04]. • Our solution: • Handoff Notifications: Implicit Handoff Notification and Explicit Handoff Notification • Enhanced Service Agility Schemes: Fast Rate Adaptation and Early Rate Reduction QShine 2005, Orlando, Florida

  4. Implicit Handoff Notification • Vertical handoffs usually result in drastic changes in the link capacity. • By monitoring the end-to-end capacity, one can identify the occurrence of a vertical handoff. • Passive capacity monitoring tools:TFRC Probe & TCP Probe (CapProbe based) QShine 2005, Orlando, Florida

  5. 20Mbps 10Mbps 5Mbps 10Mbps 20Mbps 8Mbps T1 Narrowest Link T2 T3 T3 T3 T3 Background on CapProbe Capacity = (Packet Size) / (Dispersion) QShine 2005, Orlando, Florida

  6. TFRC: TCP Friendly Rate Control • TFRC is an equation based unicast protocol. • TFRC mimics the TCP long-term throughput by utilizing the function: • The receiver is responsible for calculating the loss event rate p and sending it back to the sender once per round-trip time. • The sender is responsible for adjusting its sending rate Tactual to be close to T. QShine 2005, Orlando, Florida

  7. TFRC Probe • Embed CapProbe algorithm within TFRC by sending two packets back-to-back every n packets • TFRC Probe was assessed in [E2EMON’04]. QShine 2005, Orlando, Florida

  8. CapProbe: Delayed Ack TCP Probe: TCP Probe • TCP Probe was assessed in [GI’05]. QShine 2005, Orlando, Florida

  9. Implicit Handoff Notification • TCP/TFRC Probe continuously estimate the link capacity, using 50 samples per estimate. • A vertical handoff can be identified when a dramatic capacity change is observed. • An IHN is generated when • Cnew > αCpre or • Cnew < βCpre where α =5 and β=0.2. QShine 2005, Orlando, Florida

  10. Enhancing QoS using IHN • Fast Rate Adaptation (FRA) • FRA monitors the capacity. • When vertical handoff from LOW to HIGH is observed, FRA changes ssthresh of TCP/TFRC. • TCP/TFRC enter slow start, instead of staying in congestion avoidance. • FRA+IHN is end-to-end. • However, IHN does not work with HIGH to LOW handoff. • Decreasing ssthresh does not change TCP/TFRC behavior. QShine 2005, Orlando, Florida

  11. Explicit Handoff Notification • Need an “Intelligent Handoff Manager”. • EHN is generated prior tothe occurrence of handoff. • Smart Decision Model QShine 2005, Orlando, Florida

  12. Enhancing QoS using EHN • LOW-to-HIGH: • Fast Rate Adaptation (FRA) • HIGH-to-LOW: • Early Rate Reduction (ERR):Reduce rate in advance to prevent bulk packet losses. QShine 2005, Orlando, Florida

  13. Evaluation • Simulation Scenario (NS-2) • Vertical handoff between 802.11b (5.5Mbps) and 1xRTT (150kbps). QShine 2005, Orlando, Florida

  14. Evaluation • TFRC: vertical handoff from LOW to HIGH QShine 2005, Orlando, Florida

  15. Evaluation • TCP: vertical handoff from LOW to HIGH QShine 2005, Orlando, Florida

  16. Evaluation • TFRC: vertical handoff from HIGH to LOW • EHN (a): EHN when the handoff occurs • EHN (b): EHN one OWD before the handoff QShine 2005, Orlando, Florida

  17. Evaluation • TFRC: vertical handoff from HIGH to LOW QShine 2005, Orlando, Florida

  18. Summary • We have proposed IHN and EHN to notify the sender about the occurrence of vertical handoff. • We have proposed FRA (for IHN) and ERR (for IHN/EHN) for better QoS for vertical handoff. QShine 2005, Orlando, Florida

  19. Thank you • Questions are welcome. • For more info, please visit our web athttp://www.cs.ucla.edu/NRL/ QShine 2005, Orlando, Florida

More Related