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Wireless TCP Performance Issues

Wireless TCP Performance Issues. Slides originally from Carey Williamson CPSC 441. Hard to distinguish losses here from losses here. Example #1. Wireless TCP Performance Problems. Low capacity, high error rate. Wired Internet. High capacity, low error rate. Wireless Access.

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Wireless TCP Performance Issues

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  1. Wireless TCP Performance Issues Slides originally from Carey Williamson CPSC 441 CPSC 441

  2. Hard to distinguish losses here from losses here Example #1 • Wireless TCP Performance Problems Low capacity, high error rate Wired Internet High capacity, low error rate Wireless Access CPSC 441

  3. Example #1 (Cont’d) • Solution: “wireless-aware TCP” (I-TCP, ProxyTCP, Snoop-TCP, split connections...) CPSC 441

  4. DATA DATA Loss of ACK = Loss of DATA ACK ACK Example #2 • Wireless TCP Fairness Problems D Wired Internet Wireless Bottleneck AP U CPSC 441

  5. Example #3 • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  6. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  7. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  8. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  9. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  10. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  11. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  12. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  13. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  14. Example #3 (Cont’d) • Multi-hop “ad hoc” networking Kelly Carey CPSC 441

  15. Example #3 (Cont’d) • Two interesting subproblems: • Dynamic ad hoc routing: node movement can disrupt the IP routing path at any time, disrupting TCP connection; yet another way to lose packets!!!; possible solution: Explicit Loss Notification (ELN)? Handoff? Route prediction? • TCP flow control: the bursty nature of TCP packet transmissions can create contention for the shared wireless channel among forwarding nodes; collisions between DATA and ACKs possible solution: rate-based flow control? Burst mode? Spatial reuse of channels? CPSC 441

  16. Summary of Wireless TCP • TCP is the “four wheel drive” of TP’s • Wireless is a newly emerging technology with rapidly growing deployment popularity • “TCP” and “Wireless” don’t fit together all that well • Making TCP smarter about wireless helps! CPSC 441

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