doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) MAC Extensions for Increasing Aggregate WLAN Throughput Notice: This document has been prepared to assist IEEE 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 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 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at. Date: Authors:

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) MAC Extensions for Increasing Aggregate WLAN Throughput Mathilde Benveniste Background:

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Introduction A MAC protocol that allows parallel use of multiple channels can boost WLAN aggregate throughput beyond what a link protocol can The CCC MAC achieves higher BSS/mesh aggregate throughput through the parallel use of multiple channels Multiple-radio stations enable higher throughput at traffic concentration points Both existing and new link technologies (11/11b/ 11g/11a/11n) can be used with CCC

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Multi-channel BSS/mesh AP WiFi phone HDTV Camcorder Desktop PDA Laptop Printer Dual WiFi/cell camera phone Multimedia games MP3 Player DVD Player Camera

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Description of Common Control Channel (CCC) MAC Protocol

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Basic protocol description One control and multiple data channels are available for use in a BSS or mesh CCC works with 1, 1.5, … or n radios Control Channel Stations reserve time on data channels by exchanging CC-RTS/CC-CTS on the control channel –CC-RTS/CC-CTS indicate channel being reserved –A dedicated radio (receiver) monitors reservations on control channel –Control channel may carry data Control channel can serve data channels of diverse PHYs (11b/a/g/n) Data Channels Data radio transmits/receives data on one of multiple data channels A device may have multiple data radios for higher node throughput Acknowledgements Acknowledgements may be sent on same channel as data or on control channel –CC-Ack needed for multiple-radio devices

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) time TXOP CC-RTS CC-CTS Radio Frequency DC 2 DC 1 CC DC 3 CC-RTS CC-CTS CC-RTS CC-CTS CC-RTS CC-CTS CCC MAC protocol

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Multi-channel BSS under CCC MAC Example: AP, WiFi phone and PDA have 1 radio All other devices have 1.5 (2) radios AP WiFi phone HDTV Camcorder Desktop PDA Laptop Printer 3 channels in use CC (control channel) DC (data channels) DVD Player Legacy APs and legacy non-AP stations can co-exist with CCC stations

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) WLAN traffic load concentration calls for multi-radio stations Infrastructure APs concentrate BSS traffic –A multi-radio AP will accommodate high aggregate BSS throughput For meshes, load increases (geometrically) with the number of mesh APs (hops) as paths converge toward the portal –The total load through the portal is the sum of the loads offered at the mesh APs –Multi-radio devices are needed closer to the portal of a mesh and at APs with heavy traffic loads Load =x Load =3x Load =7x Load =15x Portal Load =30x Mesh AP

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Multi-radio CCC AP serves CCC and legacy stations on multiple channels Multi-channel multi-radio BSS/mesh under CCC MAC Example: Some handheld devices have 1 radio AP has 2.5 (3) radios; other devices have 1.5 (2) radios AP WiFi phone HDTV Camcorder Desktop PDA Laptop Printer Dual WiFi/cell camera phone Multimedia games MP3 Player 4 channels in use CC (control channel) DC (data channels) PVR Camera

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Adjacent Channel Interference Multi-radio devices can suffer adjacent channel interference (ACI) while transmitting and receiving simultaneously on adjacent channels The number of available non-adjacent data channels is small –The available unlicensed RF spectrum has several segments of channels: one in 2.4 GHz range and 3 (or 4) in the 5 GHz range –Channels from different segments would not cause one another ACI Avoiding ACI by using only ‘non-adjacent’ channels lowers efficiency of channel use –Low channel re-use – only a few channels can be used by multi- radio MPs in the mesh

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Proposed Solution 1.The control and data channels are selected so that the control channel is not adjacent to any of the data channels 2.Data channels may be adjacent to one another, as long as there is no simultaneous transmission and reception by the same device on adjacent channels –A transmission is delayed if a station is receiving and there is no non-adjacent channel available –A reservation is declined if the request is for a channel adjacent to the one the station is transmitting on –Acknowledgements between end points involved in adjacent- channel transmissions must be sent on the control channel 1 Summary description of CCC features

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) Summary With the CCC MAC, stations in a BSS or mesh points can access in parallel a pool of channels, not just one channel At nodes of high traffic concentration, a device can operate on multiple radios at once without ACI Few radios can leverage the full capacity of a channel pool –High-throughput devices (multi-radio APs or mesh portals) can communicate with low throughput devices without loss of capacity CCC is backward compatible with existing devices –CCC stations can co-exist with legacy APs and non-AP stations CCC can be used with any mix of PHY channels, including 11n CCC used with 11n channels multiplies the throughput increase beyond what is attainable by 11n alone 1 Summary description of CCC features

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) References 1.M. Benveniste, "CCC Mesh MAC Protocol," IEEE s Document, DCN /0610r1, June 2005, 2.M. Benveniste, "CCC MAC Protocol Framework and Optional Features," IEEE s Document, DCN /0880r0, September 2005, M. Benveniste and Z. Tao, "Performance Evaluation of a MAC Protocol for s Mesh Networks," 2006 IEEE Sarnoff Symposium, Princeton, NJ, March 2006, M. Benveniste, “Avoiding Adjacent Channel Interference with Multi-Radio Mesh Points,” IEEE s Document, DCN /1123r0, November 2005, 1 Summary description of CCC features

doc.: IEEE /0408r2 Submission March 2006 M. Benveniste (Avaya Labs) CCC and 11n CCC can be added to n as an optional feature!