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A nticipatory Wireless Bitrate Control for Blocks

A nticipatory Wireless Bitrate Control for Blocks. X iaozheng Tie, Anand Seetharam, Arun Venkataramani, Deepak Ganesan, Dennis Goeckel U niversity of Massachusetts Amherst. Wireless bitrate control. Goal: To optimize goodput by adapting effective sending rate to channel quality. 6M bps.

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A nticipatory Wireless Bitrate Control for Blocks

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  1. Anticipatory Wireless Bitrate Control for Blocks Xiaozheng Tie, Anand Seetharam, Arun Venkataramani, Deepak Ganesan, Dennis Goeckel University of Massachusetts Amherst

  2. Wireless bitrate control • Goal: To optimize goodput by adapting effective sending rate to channel quality 6Mbps Bad channel Data packet 1Mbps Channel feedback Good channel 2Mbps Good channel 

  3. Blocks reduce overhead • Blocks = Large batch of packets • E.g., 64KB MAC block in 802.11n • 1MB block in Hop transport [NSDI’09] DIFS DIFS Backoff Backoff Packet X SIFS X X X Ack Timeout SIFS Backoff DIFS Backoff  Block transmission Packet transmission

  4. Responsiveness vs. overhead 6Mbps 6Mbps 6Mbps 6Mbps 6Mbps X 6Mbps 1Mbps X 6Mbps X 6Mbps 2Mbps Can we have both high responsiveness and low overhead? • Block transmission • Low responsiveness • Low overhead • Packet bitrate control • High responsiveness • High overhead

  5. Outline • Why anticipatory bitrate control • BlockRate design and implementation • Evaluation • Conclusion

  6. Overhead vs. responsiveness (1) 1.6x [Mobisys’08] (Block-based) (Packet-based) (Block-based) Overhead matters more in static settings

  7. Overhead vs. responsiveness (2) • Both overhead and responsiveness matter in mobile settings Data 30mph   2x 6Mbps 6Mbps 6Mbps 6Mbps 1.7x 12Mbps 6Mbps 12Mbps 6Mbps 12Mbps   Oracle+Block Charm+Block

  8. Outline • Why anticipatory bitrate control • BlockRate design and implementation • Evaluation • Conclusion

  9. Anticipatory bitrate control • Anticipatory = Selecting multiple bitrates predictive of future channel conditions. 6Mbps 6Mbps 6Mbps 6Mbps 12Mbps 6Mbps Good channel 12Mbps 6Mbps 12Mbps 12Mbps Anticipatory bitrate control for blocks Bitrate control for packets

  10. Predict SNR trend: Slow-changing • Linear regression model • Assumes SNR linearly varies with time in slow-changing scenarios Pedestrian (1m/s) Static

  11. Predict SNR trend: Fast-changing • Path loss model • Assumes SNR logarithmically varies with distance in fast-changing scenarios SNR(d)= SNR(d0) – 10αlog(d/d0) 30mph

  12. BlockRate design summary Slow mobility? 30dB No 6Mbps Yes Linear regression 6Mbps 40dB 12Mbps Path loss 12Mbps  1. Predict future SNR based on mobility pattern 2. Lookup SNR-Bitrate table to select anticipatory bitrate

  13. SNR-Bitrate table • Maintains bitrate that maximizes goodput at each SNR

  14. Outline • Why anticipatory bitrate control • BlockRate design and implementation • Evaluation • Conclusion

  15. Experimental setup Pedestrian Vehicular Static V-to-V: 20 buses 2 mobile laptops Mesh:16 MacMini nodes Pedestrian ns3 simulation V-to-AP: 2 cars

  16. Performance in V2V testbed 1.3x

  17. Performance in V-to-AP testbed Data 30mph 1.6x

  18. Performance in pedestrian mobility • Pedestrian mobility trace-driven simulation in ns-3 (Uses PHY-hint) (Uses movement-hint)

  19. Conclusion • State-of-the-art bitrate control schemes must pick one: low overhead or high responsiveness • BlockRate achieves both benefits • Anticipatory bitrate control using blocks reduces overhead while being responsive Thank you!

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