Leader based Multicast Date: 2007-1-18 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>. Yongho SEOK

Abstract This document proposes the leader based multicast mechanism. First, we introduce the problems of the current 802.11 multicast mechanism. Second, we propose the leader based multicast mechanism to improve the multicast performance. Third, we show the benefits of the leader based multicast mechanism with the experimental results. At the end of the presentation, there will be a motion to include normative text of this proposal in 802.11v draft. Yongho SEOK

Introduction Increasing quantity of WiFi enabled portable devices Growing availability of multimedia streaming Increasing WiFi coverage on public places The best option: Multicast Yongho SEOK

Problem Current implementation of Multicast: Open Loop Transmission No CW adaptation No rate adaptation No retransmission Multicast transmission starts Yongho SEOK

Proposed solution Leader-based Multicast: [Kuri and Kasera] -Choose one receiver as the Leader Send back ACK to the AP STA1 STA2 STA4 STA3 ACK STA5[Leader] Yongho SEOK

Proposed solution Leader Election Protocol Leader is elected using three Action frames Leader Selection Algorithm -It is possible to utilize IEEE 802.11v multicast diagnostic capability The station with the highest PER may be selected to the Leader New Leader Old Leader New Leader Old Leader New Leader Old Leader (a) Leader Request Action (b) Leader Response Action (b) Leader Release Action Yongho SEOK

Experimentation: Platform 5 Probes for data acquisition and traffic generation 1 Software-based Access Point Uniform Wireless Hardware (Atheros-based Proxim cards) Wireless Probe Wireless Probe Wireless Probe Wireless Probe Wireless Probe Yongho SEOK

Experimentation: Controlled conditions 4 Experiments: 5 tests of 5 minutes of VBR video streaming Legacy Multicast without background traffic Legacy Multicast with TCP background traffic Leader based without background traffic. Leader based with TCP background traffic Yongho SEOK

Results Video Goodput for both mechanisms Leader based Legacy Multicast Yongho SEOK

Results Packet Loss Correlation without retransmissions Uncorrelated Collision Collision Uncorrelated Yongho SEOK

Conclusion Leader based solution: Better throughput than Legacy multicast Can follow the VBR test video requirements Increases throughput with retransmissions on a loaded network Low complexity to be implemented Compatible with legacy 802.11 station Yongho SEOK

Motion Move to include normative text in document 11-07-0144-00-000v-normative-text-leader-based-multicast.doc into the TGv draft. Mover: Seconder: Result: Yongho SEOK