PPT

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PPT

  1. 1. Adaptive Video Streaming in Vertical Handoff: A Case Study Ling-Jyh Chen, Guang Yang, Tony Sun, M. Y. Sanadidi, Mario Gerla Computer Science Department, University of California at Los Angeles
  2. 2. Adaptive Video Streaming in Vertical Handoff: A Case Study Outline of the Talk  The problem: the performance of video streaming may degrade due to wireless channel errors and vertical handoffs.  Key idea:  Adaptive video delivery can improve the end user’s perceived quality.  Seamless handoff can provide uninterrupted services even with the presence of mobility.  The results: we show that the combination of adaptive video streaming and seamless handoff can go a long way in providing better video streaming in mobile computing scenarios. Aug. 24, 2004 MobiQuitous 2004 2
  3. 3. Adaptive Video Streaming in Vertical Handoff: A Case Study Introduction  Mobile Computing Scenarios Mobility Aug. 24, 2004 MobiQuitous 2004 3
  4. 4. Adaptive Video Streaming in Vertical Handoff: A Case Study Introduction (cont.)  Three issues: 1. Seamless mobility across heterogeneous networks. 2. Adaptation to network dynamics such as wireless channel errors and congestion. 3. Application adaptation to maximize the end user’s perceived quality. Aug. 24, 2004 MobiQuitous 2004 4
  5. 5. Adaptive Video Streaming in Vertical Handoff: A Case Study Background – Seamless 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. Aug. 24, 2004 MobiQuitous 2004 5
  6. 6. Adaptive Video Streaming in Vertical Handoff: A Case Study Background – Seamless 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)  Middleware Approach (e.g. USHA) Q: Which seamless handoff solution are you using? Aug. 24, 2004 MobiQuitous 2004 6
  7. 7. Adaptive Video Streaming in Vertical Handoff: A Case Study Proposed Approach: USHA  Universal Seamless Handoff Architecture NAT server NAT Server All packets are encapsulated and transmitted using UDP Applications are bound to the tunnel and transparent to the handoff. Aug. 24, 2004 MobiQuitous 2004 7
  8. 8. Adaptive Video Streaming in Vertical Handoff: A Case Study Background – Video Streaming Best-effort streaming Real-time streaming adapt sending rate adapt sending rate and stream quality SCP Helix RAP Microsoft TEAR VTP TFRC Aug. 24, 2004 MobiQuitous 2004 8
  9. 9. Adaptive Video Streaming in Vertical Handoff: A Case Study Proposed Approach: VTP  Video Transport Protocol 1. Bandwidth Estimation k 1 dj l Achieved Rate Measurement: bj l 0 tj tj ( k 1) bj bj 1 Available Bandwidth Estimation: B j Bj 1 (1 ) 2 Assume we use packet trains of length k to measure the achieved rate. Denote di as the number of bytes in packet i, ti as the time when packet i arrives at the client. Aug. 24, 2004 MobiQuitous 2004 9
  10. 10. Adaptive Video Streaming in Vertical Handoff: A Case Study Proposed Approach: VTP (cont.) 2. Rate Adaptation: Multiple streams of the same content are encoded at different rates. DR: Decreasing Rate State IR: Increasing Rate State Q0: Lowest Quality Video (56Kbps) Q1: Normal Quality Video (150Kbps) Q2: Highest Quality Video (500Kbps) Aug. 24, 2004 MobiQuitous 2004 10
  11. 11. Adaptive Video Streaming in Vertical Handoff: A Case Study Proposed Approach: VTP (cont.) 3. Variable Bit Rate (VBR) Video  VTP divides a video clip into a number of segments.  For each segment, VTP computes a target rate, at which neither buffer overrun or underrun should occur.  Since video streams are pre-stored, instantaneous sending rates are available beforehand, and so are the target rates of the segments.  VTP applies these target rates to the finite state machine for rate adaptation. Aug. 24, 2004 MobiQuitous 2004 11
  12. 12. Adaptive Video Streaming in Vertical Handoff: A Case Study Experiments  VTP server/client are implemented on Linux.  USHA system is set up on Linux, with custom configured NAT and IP tunneling.  VTP client is connected to the Internet via 802.11b and 1xRTT, which is provided by Verizon Wireless.  Two vertical handoff scenarios are tested: 1. From 1xRTT to 802.11b 2. From 802.11b to 1xRTT Aug. 24, 2004 MobiQuitous 2004 12
  13. 13. Adaptive Video Streaming in Vertical Handoff: A Case Study Experiments: 1xRTT to 802.11b  Non-adaptive Video Streaming Frame Rate received at the Mobile Host Sending Rate at the Video Server Aug. 24, 2004 MobiQuitous 2004 13
  14. 14. Adaptive Video Streaming in Vertical Handoff: A Case Study Experiments: 1xRTT to 802.11b  Adaptive Video Streaming Video Qualityreceivedthe the Mobile Host Frame Rate sent at at Video Server Sending Rate at the Video Server Aug. 24, 2004 MobiQuitous 2004 14
  15. 15. Adaptive Video Streaming in Vertical Handoff: A Case Study Experiments: 802.11b to 1xRTT  Non-adaptive Video Streaming Frame Rate received at the Mobile Host Sending Rate at the Video Server Aug. 24, 2004 MobiQuitous 2004 15
  16. 16. Adaptive Video Streaming in Vertical Handoff: A Case Study Experiments: 802.11b to 1xRTT  Adaptive Video Streaming Frame Rate received at the Video Server Video Quality sent at the Mobile Host Sending Rate at the Video Server Aug. 24, 2004 MobiQuitous 2004 16
  17. 17. Adaptive Video Streaming in Vertical Handoff: A Case Study Discussion  Drastic changes in the link capacity are often associated with vertical handoffs.  Most traditional streaming algorithms incorporate the well-known slowly-responsive congestion control (SlowCC) and thus cannot take aggressive advantage of the rapid change of resources in emerging vertical handoff scenarios. Aug. 24, 2004 MobiQuitous 2004 17
  18. 18. Adaptive Video Streaming in Vertical Handoff: A Case Study Discussion (cont.)  For a handoff from LOW to HIGH, VTP can properly and rapidly adapt its sending rate and video quality to available bandwidth, and hence is successful in handling vertical handoffs.  For a handoff from HIGH to LOW, application performance would benefit if the server could predict the handoff and thus adapt its sending rate in advance. Aug. 24, 2004 MobiQuitous 2004 18
  19. 19. Adaptive Video Streaming in Vertical Handoff: A Case Study Conclusion  We studied the need and evaluated the performance of adaptive video streaming in vertical handoff scenarios.  Experiments with handoffs from 1xRTT to 802.11b and vice versa have been carried out to evaluate the performance of our proposed solution.  Such a combination of adaptive video streaming and seamless vertical handoff will become desirable in the emerging ubiquitous mobile computing environment. Aug. 24, 2004 MobiQuitous 2004 19
  20. 20. Adaptive Video Streaming in Vertical Handoff: A Case Study Thanks! Aug. 24, 2004 MobiQuitous 2004 20

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