1. Proposed 802.11 MAC Extensions for 11n/s/p
May 2006
Proposed MAC Extensions for 11n/s/p
Date:
Authors:
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 < 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 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
M. Benveniste (Avaya Labs)

2. Proposed Multi=Purpose 802.11 MAC Extensions
May 2006
Proposed Multi=Purpose MAC Extensions
Mathilde Benveniste
Background:
M. Benveniste (Avaya Labs)

3. May 2006
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 shorter delays and higher BSS/mesh aggregate throughput through the parallel use of multiple channels
facilitates multiple-radio station operation with higher throughput to avoid bottlenecks at traffic concentration points
Both existing and new link technologies (11/11b/ 11g/11a/11n) can be used together with CCC
M. Benveniste (Avaya Labs)

4. Multi-channel BSS/mesh
May 2006
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
M. Benveniste (Avaya Labs)

5. Description of Common Control Channel (CCC) MAC Protocol
May 2006
Description of Common Control Channel (CCC) MAC Protocol
M. Benveniste (Avaya Labs)

6. Basic protocol description
May 2006
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
M. Benveniste (Avaya Labs)

7. CCC MAC protocol May 2006 TXOP TXOP TXOP TXOP time Radio Frequency
CC-RTS
CC-CTS
CC-RTS
CC-CTS
CC-RTS
CC-CTS
CC-RTS
CC-CTS
DC 2
DC 1 CC
DC 3
TXOP
TXOP
TXOP
TXOP
time
Radio
Frequency
M. Benveniste (Avaya Labs)

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

9. on both data and control channel on both data and control channel
May 2006
Multi-channel multi-radio BSS/mesh under CCC MAC Example: Some handheld devices have 1 radio AP and other devices have 1.5 (2) radios
PVR
WiFi phone
Dual WiFi/cell
camera phone
PDA
MP3 Player
AP communicates
on both data and control channel
DLS transmissions
on both data and control channel
HDTV AP
Desktop
CCC AP
serves CCC
and legacy stations
on multiple channels
Multimedia
games
4 channels in use
CC (control channel) DC
(data channels)
Laptop
Printer
Camcorder
Camera
M. Benveniste (Avaya Labs)

10. WLAN traffic load concentration calls for multi-radio stations
May 2006
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
M. Benveniste (Avaya Labs)

11. Adjacent Channel Interference
May 2006
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
Using ‘non-adjacent’ channels only to avoid ACI lowers efficiency of channel use
Low channel re-use – only a few channels can be used by multi-radio MPs in the mesh
M. Benveniste (Avaya Labs)

12. CCC solution to avoid ACI
1 Summary description of CCC features
May 2006
CCC solution to avoid ACI
The control and data channels are selected so that the control channel is not adjacent to any of the data channels
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 control channel
M. Benveniste (Avaya Labs)

13. 802.11n – CCC in High Throughput
May 2006
802.11n – CCC in High Throughput
HT will provide high link and aggregate network throughput
CCC enables
Use of multiple-radio devices to increase link throughput; the control channel can be used simultaneously with another channel
Any one of multiple channel(s) can be used by different streams in BSS to increase aggregate throughput, even beyond what’s possible with current TGn proposal
M. Benveniste (Avaya Labs)

14. 802.11s – CCC in ESS Mesh (Extended Service Set Mesh)
May 2006
802.11s – CCC in ESS Mesh (Extended Service Set Mesh)
ESS Mesh – Wireless distribution system for multiple APs and coverage extension
High aggregate throughput and high link rates
The traffic of multiple APs is conveyed
CCC capabilities
Multiple-channel access – continuous asynchronous access of different channels on different links, based on availability
Multiple-radio devices transmit/receive over multiple non-adjacent or adjacent channels simultaneously, without adjacent-channel interference – to avert bottlenecks near portal
M. Benveniste (Avaya Labs)

15. 802.11p – CCC in WAVE (Wireless Access in Vehicular Environment)
May 2006
802.11p – CCC in WAVE (Wireless Access in Vehicular Environment)
WAVE – Communications between roadside APs and vehicles and between vehicles
Very short latencies
Some applications must complete multiple data exchanges within 4 to 50ms
CCC enables
Quick short reservation on control channel – high priority access
Choice of one of many data channels to perform the data exchange
M. Benveniste (Avaya Labs)

16. 1 Summary description of CCC features
May 2006
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 (CCA and Virtual Carrier Sense observed)
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 (e.g. audio/video applications)
CCC is an optional feature; implementation poses no requirements on non-CCC devices
M. Benveniste (Avaya Labs)

17. 1 Summary description of CCC features
May 2006
References
M. Benveniste, "CCC Mesh MAC Protocol," IEEE s Document, DCN /0610r1, June 2005,
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,
M. Benveniste (Avaya Labs)