1. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 1 Multi-rate Effects on Direct Link Setup Notice: This document has been prepared to assist IEEE 802.11. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures, including the statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the Chair as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at.http:// ieee802.org/guides/bylaws/sb-bylaws.pdfstuart.kerry@philips.compatcom@ieee.org Date: 2007-07-17 Authors:

2. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 2 Abstract This submission addresses the performance anomaly problem of DLS when it is under multi- rate capability

3. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 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

4. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 4 Remember this: “IEEE 802.11PHY 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 5.5Mbps2Mbps1Mbps

5. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 5 Side Effects of Multi-rate Capability: “Performance Anomaly Problem” IEEE 802.11 MAC guarantees the throughput fairness. –All nodes have the same probability of channel access –When slow node captures the channel, it holds the channel longer than faster node Degradation of overall network performance

6. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 6 What Do You Want to Define ? In an infrastructure network having STA-a and STA-b –Establish a session though AP to exchange frames –Exchange frames without intervention of AP –Teardown the session STA-a STA-b AP

7. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 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 one is better? –{STA-a, AP, STA-b} –{STA-a, STA-b} How do you know it?

8. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 8 Straw Poll Do you want to consider the Multi-rate DSL Environment? –Yes/No/Abstain:

9. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 9 Backup Slides

10. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 10 Adaptation of the Number of Tx Frames* ACK (without contention) … 11Mbps: 5 ~6 packets 5.5Mbps: 2~3 packets 2Mbps: 1 packet Backoff + RTS/CTS Channel access time Adjust the number of transmission frames –Higher-rate node sends more frames than lower-rate node *B. Sadeghi, V. Kanodia, A. Sabharwal, and E. Knightly, “Opportunistic Media Access for Multi-rate Ad Hoc Networks,” ACM MobiCom, 2002.

11. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 11 Adaptation of Maximum Transmission Unit* Adjust the frame sizes proportionally depending on data rate –Higher-rate node sends longer frames than lower-rate node 11Mbps 5.5Mbps2Mbps Channel access time *S. Yoo, J. Choi, J. Hwang, and C. Yoo, “Eliminating the Performance Anomaly of 802.11b," ICN, 2005.

12. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 12 Transmission Time Separation* Allocate different time intervals to each transmission rates Super-frame Sub-frame 1 Sub-frame 2 Sub-frame 3 Contention among nodes with rate 1 5.5Mbps2Mbps *T. Kuang, and Q. Wu, “MRMC: A Multi-Rate Multi- Channel MAC Protocol for Multi-Radio Wireless LANs,” IEEE WiNCS, 2005. 11Mbps

13. doc.: IEEE 802.11-07/2191r0 Submission July 2007 Y. Jeong, et al.Slide 13 Channel A : 11Mbps Channel B : 5.5Mbps Channel C : 2Mbps Channel Separation* Allocate different channels to each transmission rates –Channel separation *C. T. Im and D. H. Kwon, “A Rate Separation Mechanism for Performance Improvements of Multi-rate WLANs,” ICCSA, 2005.