1. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 1 CoopMAC: A cooperative MAC compliant with IEEE 802.11 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 IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs 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: 2006-11-13 Authors:

2. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 2 Abstract This talk presents a new Cooperative MAC protocol called CoopMAC: CoopMAC takes advantage of the multi-rate capability of the current 802.11 standard and assists slow stations, improving the performance of the whole network. A slow station, instead of sending its packets using a slow one hop transmission, uses a helper, i.e. a station that is located between the transmitter and the receiver, and sends its packets by using a two fast hop transmission. CoopMAC can be applied with AND without physical layer cooperation, and achieves significant improvement in both cases. A preliminary demo shows that CoopMAC outperforms 802.11 in a real environment.

3. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 3 Motivation for Cooperation Wireless link is unreliable (broadcast channel + diversity) Solution: Use another mobile to relay information Optional function: The destination can process signals from both mobiles –Spatial diversity through relays antenna Results in –Higher reliability, higher data rates, increased battery life, extended coverage Source Helper Destination

4. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 4 STA1 STA2 Access point Motivation for Cooperation Leverage both the cooperation and multirate capabilities of 802.11 MAC Without Cooperation T 1 (STA1 AP) 11Mbps T 2 (STA2 AP) With Cooperation T 3 (STA1 STA2)T 4 (STA2 AP)T 5 (STA2 AP) 1Mbps 11Mbps

5. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 5 STA1 STA2 Access point Cooperative MAC (CoopMAC) Procedure for selecting a helper Look up the Cooperation Table Find the one that satisfies the following condition –Time [Direct Tx] > Time [Two-hop Relaying] If the information is not stale, use the helper. Data transmission procedure Handshake RTS (Ready To Send) HTS (Helper ready To Send) CTS (Clear To Send) Data transmission Acknowledgement RTS HTS CTS Data ACK

6. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 6 Performance I mprovement Cooperative MAC significantly improves the network performance (throughput). Simulation settings: –Saturation load, with frame size of 1500 bytes Network Capacity

7. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 7 Performance I mprovement Cooperative MAC significantly improves the network performance (delay). Simulation settings: –Saturation load, with frame size of 1500 bytes Channel Access Delay

8. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 8 Performance I mprovement Cooperative MAC significantly improves the network performance (energy efficiency). Simulation settings: –Saturation load, with frame size of 1500 bytes Energy Efficiency

9. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 9 Implementation approach Platform –Based upon HostAP driver on a Linux platform. Firmware limitations –Time sensitive functions (e.g. Ack transmission) are controlled by the firmware. Packet format –A new header is introduced. IEEE 802.11b PHY IEEE 802.11 DCF MAC Intersil Prism chipset Firmware on the chip HostAP Driver in Linux kernel Protocol stack 802.11 PHY Preamble & Header Src Addr Payload Cooperation Header 802.11 MAC Header Dest Addr Helper Addr New header format

10. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 10 Experimental Throughput Comparison UDP TCP Experiment settings: –1 source, 1 helper and 1 receiver. –No active traffic from the helper. Major finding: Both UDP and TCP traffic enjoy the benefit of CoopMAC Simulation settings: 1000 bytes payload size

11. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 11 Better to Give than to Receive UDP Experiment settings: –1 source, 1 helper and 1 receiver. –Helper is now active. Major finding: Helper enjoys the benefit of Cooperation

12. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 12 Network throughput Major finding: Overall Network throughput is very high in CoopMAC compared to 802.11

13. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 13 Demo A full functional video streaming demo shows the benefits of CoopMAC protocol. –The demo consists of 4 laptops (receiver, transmitter, 2 candidate helpers). –The helpers provide different transmission rates to the transmitter for the two hop. –The transmitter dynamically selects the best helper. –The video quality at the receiver varies, depending on the two hop rates.

14. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 14

15. doc.: IEEE 802.11-06-1642-00-0wng Submission November 2006 Thanasis Korakis, Polytechnic UniversitySlide 15 Conclusion The new Cooperative MAC protocol: –Significantly improves the performance of 802.11. –Can be combined to cooperative schemes on the Physical layer. –It is backward compatible with 802.11. –Can be applied on top of 802.11 as an assisting mechanism. –It is different from mesh networks multi-hop relying. –Easy to implemented by changing the driver and the firmware of the card. Any help available to further proceed with the implementation of the protocol?