March 2006 doc IEEE 802 11 -06 0408

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 802. 11 MAC Extensions for Increasing Aggregate WLAN Throughput Mathilde Benveniste benveniste@ieee. org Background: http: //pubs. research. avayalabs. com/pdfs/CCC_High_throughput_MAC. pdf Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 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 (11/11 b/ 11 g/11 a/11 n) can be used with CCC Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 Multi-channel BSS/mesh Dual Wi. Fi/cell camera phone DVD Player HDTV Wi. Fi phone PDA MP 3 Player AP Desktop Multimedia games Laptop Camcorder Submission Printer Camera M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 Description of Common Control Channel (CCC) MAC Protocol Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 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 (11 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 – Needed for multiple-radio devices Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 CC-RTS CC-CTS CCC MAC protocol CC DC 1 DC 2 DC 3 TXOP time Radio Frequency Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 Multi-channel BSS under CCC MAC Example: AP, Wi. Fi phone and PDA have 1 radio All other devices have 1. 5 (2) radios PDA DVD Player Wi. Fi phone HDTV AP Legacy APs and Desktop legacy non-AP stations can co-exist with CCC stations 3 channels in use CC (control channel) DC Laptop Camcorder Printer (data channels) Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 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 =30 x Load =15 x Load =7 x Load =3 x Portal Mesh AP Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 Multi-channel multi-radio BSS/mesh under CCC MAC Example: Wi. Fi phone and PDA have 1 radio AP has 2. 5 (3) radios; all other devices have 1. 5 (2) radios Dual Wi. Fi/cell camera phone DVD Player HDTV Wi. Fi phone PDA MP 3 Player AP Desktop Multi-radio CCC AP Multimedia games serves CCC and legacy stations 4 channels in use CC (control channel) DC (data channels) Submission Laptop Camcorder Printer Camera M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 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 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 multiradio MPs in the mesh Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 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 – – – Submission 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 adjacentchannel transmissions must be sent on the control channel M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 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 – • CCC is backward compatible with existing 802. 11 devices – • • High-throughput devices (APs or mesh portals) can communicate with low throughput devices without loss of capacity CCC stations can co-exist with legacy APs and non-AP stations CCC can be used with any mix of PHY channels, including 11 n CCC used with 11 n channels multiplies the throughput increase beyond what is attainable by 11 n alone Submission M. Benveniste (Avaya Labs)

March 2006 doc. : IEEE 802. 11 -06/0408 r 0 References 1. 2. 3. 4. M. Benveniste, "CCC Mesh MAC Protocol, " IEEE 802. 11 s Document, DCN 802. 11 -05/0610 r 1, June 2005, https: //802 wirelessworld. com M. Benveniste, "CCC MAC Protocol Framework and Optional Features, " IEEE 802. 11 s Document, DCN 802. 11 -05/0880 r 0, September 2005, https: //802 wirelessworld. com M. Benveniste and Z. Tao, "Performance Evaluation of a MAC Protocol for 802. 11 s Mesh Networks, " 2006 IEEE Sarnoff Symposium, Princeton, NJ, March 2006, www. research. avayalabs. com/user/benveniste M. Benveniste, “Avoiding Adjacent Channel Interference with Multi-Radio Mesh Points, ” IEEE 802. 11 s Document, DCN 802. 11 -05/1123 r 0, November 2005, https: //802 wirelessworld. com Submission M. Benveniste (Avaya Labs)