Multi-rate Effects on Direct Link Setup Month Year doc.: IEEE 802.11-yy/xxxxr0 Multi-rate Effects on Direct Link Setup Date: 2007-07-17 Authors: 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 <http:// ieee802.org/guides/bylaws/sb-bylaws.pdf>, 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 <stuart.kerry@philips.com> 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 <patcom@ieee.org>. Y. Jeong, et al. John Doe, Some Company

Abstract This submission addresses the performance anomaly problem of DLS when it is under multi-rate capability Y. Jeong, et al.

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 Y. Jeong, et al.

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 Y. Jeong, et al.

Side Effects of Multi-rate Capability: “Performance Anomaly Problem” In single-rate environment, IEEE 802.11 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 Y. Jeong, et al.

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 Y. Jeong, et al.

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? Y. Jeong, et al.

Straw Poll Do you want to consider the Multi-rate DSL Environment? Yes/No/Abstain: Y. Jeong, et al.

Backup Slides Y. Jeong, et al.

Adaptation of the Number of Tx Frames* Month Year doc.: IEEE 802.11-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. Y. Jeong, et al. John Doe, Some Company

Adaptation of Maximum Transmission Unit* Month Year doc.: IEEE 802.11-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 802.11b," ICN, 2005. Y. Jeong, et al. John Doe, Some Company

Transmission Time Separation* Month Year doc.: IEEE 802.11-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. Y. Jeong, et al. John Doe, Some Company

Month Year doc.: IEEE 802.11-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