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1. 3. 1. 3. 2. 2. Link Neighborhood. 4. 5. 6. 4. 5. 6. 9. 1. 8. 8. 7. 9. 7. 9. 18. 18. 7. 2. 17. 17. 23. 23. 10. 10. 24. 24. 16. 16. 5. 6. Sumit Rangwala, Apoorva Jindal, Ki-Young Jang, Konstantinos Psounis, and Ramesh Govindan - PowerPoint PPT Presentation
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Proposed Solution: Proposed Solution: Neighborhood-Centric TransportNeighborhood-Centric Transport
Evaluation: Evaluation: WCP fairer than TCP, WCPCap achieves max-min fairnessWCP fairer than TCP, WCPCap achieves max-min fairness
Understanding Congestion Control in Multi-hop Understanding Congestion Control in Multi-hop Wireless Mesh NetworksWireless Mesh Networks
Sumit Rangwala, Apoorva Jindal, Ki-Young Jang, Konstantinos Psounis, and Ramesh GovindanUniversity of Southern California
What is wrong with TCP? Congestion is a Neighborhood Phenomenon
WCP: AIMD Based Transport Protocol WCPCap: Explicit Rate Control Protocol
TCP starves the middle flow
All incoming and outgoing links from the sender, receiver, all the neighbors of sender, and all the neighbors of receiver
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Link Neighborhood
Problem Description: Problem Description: Congestion Control in 802.11x Wireless NetworksCongestion Control in 802.11x Wireless Networks
Stack Topology
Diamond Topology
Chain-cross Topology Simulations: Chain-cross Topology
Simulations: Diamond Topology
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Arbitrary Topology Real-world Experiments: Arbitrary Topology
Simulations: Stack Topology
Real-world Experiments: Stack Topology
Neighborhood congestion detection Any link in the link neighborhood is congested
Neighborhood RTT Maximum RTT of all flows traversing a link neighborhood
End-to-end behavior Reduce a flow’s rate if at least one of the traversed neighborhoods
is congested Use the maximum RTT among all traversed neighborhood RTTs
to “clock” the rate changes
Neighborhood per flow rate Calculates sustainable fair rate for each flow in a link
neighborhood Requires spare capacity calculation
End-to-end behavior Flows send at a rate that is minimum of the rate assigned at each
traversed neighborhood
Experimentation Setup Simulation
Qualnet 3.9.5 802.11b with default parameters
11Mbps , no rate adaptation, 512 byte data packet Zero channel losses Buffer size: 64 packets
Real World Experiments Click modular router on Linux Same code as in simulation
Link ≡ sender-receiver pair
