1. Multi-rate Effects on Direct Link Setup
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doc.: IEEE yy/xxxxr0
Multi-rate Effects on Direct Link Setup
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2. Abstract
This submission addresses the performance anomaly problem of DLS when it is under multi-rate capability
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3. Outline Remember this: “IEEE 802.11PHY has Multi-rate Capability”
Side Effects of Multi-rate Capability: “Performance Anomaly Problem”
What Do You Want to Define ?
Straw Poll
Backup Slides
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4. Remember this: “IEEE 802.11 PHY has Multi-rate Capability”
Supports various data rate depending on modulation schemes
802.11a: 6, 9, 12, 18, 24, 36, 48, 54 Mbps
802.11b: 1, 2, 5.5, 11 Mbps
802.11g: 1, 2, 5.5, 6, 9, 11, 12, 18, 22, 24, 33, 36, 48, 54 Mbps
The longer transmission distance is required the lower data rates
11Mbps
5.5Mbps
2Mbps
1Mbps
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5. Side Effects of Multi-rate Capability: “Performance Anomaly Problem”
In single-rate environment, IEEE MAC guarantees the throughput fairness
All nodes have the same probability of channel access
However, under multi-rate environment
When slow node captures the channel, it holds the channel longer than faster node
Broke the throughput fairness
Degrade the overall network performance
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6. What Do You Want to Define ?
In an infrastructure network, DSL having STA-a and STA-b
Establish a session through AP to exchange frames
Exchange frames without intervention of AP
Teardown the session AP
STA-a
STA-b
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7. In Multi-rate Direct Link Setup Environment
The “Performance Anomaly Problem” has been more serious if there are slow links
Degrade network throughput
Which path is better?
Indirect: {STA-a, AP, STA-b}
Direct: {STA-a, STA-b}
Sometimes, indirect path may have good performance according to the link qualities (e.g. distance, BER…)
How do you know it?
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8. Straw Poll Do you want to consider the Multi-rate DSL Environment?
Yes/No/Abstain:
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9. Backup Slides
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10. Adaptation of the Number of Tx Frames*
Month Year
doc.: IEEE yy/xxxxr0
Adaptation of the Number of Tx Frames*
Adjust the number of transmission frames
Higher-rate node sends more frames than lower-rate node
ACK (without contention)
Backoff + RTS/CTS …
Channel
access time
11Mbps:
5 ~6 packets
5.5Mbps:
2~3 packets
2Mbps:
1 packet
*B. Sadeghi, V. Kanodia, A. Sabharwal, and E. Knightly, “Opportunistic Media Access for Multi-rate Ad Hoc Networks,” ACM MobiCom, 2002.
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11. Adaptation of Maximum Transmission Unit*
Month Year
doc.: IEEE yy/xxxxr0
Adaptation of Maximum Transmission Unit*
Adjust the frame sizes proportionally depending on data rate
Higher-rate node sends longer frames than lower-rate node
Channel
access time
11Mbps
5.5Mbps
2Mbps
*S. Yoo, J. Choi, J. Hwang, and C. Yoo, “Eliminating the Performance Anomaly of b," ICN, 2005.
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12. Transmission Time Separation*
Month Year
doc.: IEEE yy/xxxxr0
Transmission Time Separation*
Super-frame
Allocate different time intervals to each transmission rates
11Mbps
5.5Mbps
2Mbps
Sub-frame1
Sub-frame2
Sub-frame3
Contention among
nodes with rate1
*T. Kuang, and Q. Wu, “MRMC: A Multi-Rate Multi-Channel MAC Protocol for Multi-Radio Wireless LANs,” IEEE WiNCS, 2005.
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13. Month Year
doc.: IEEE yy/xxxxr0
Channel Separation*
Allocate different channels to each transmission rates
Channel separation
Channel A : 11Mbps
Channel B : 5.5Mbps
Channel C : 2Mbps
*C. T. Im and D. H. Kwon, “A Rate Separation Mechanism for Performance Improvements of Multi-rate WLANs,” ICCSA, 2005.
Y. Jeong, et al.
John Doe, Some Company