1. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 1 Multi-Channel CBP for Efficient Inter-Cell Communications in IEEE 802.22 IEEE P802.22 Wireless RANs Date: 2007-05-03 Authors: Notice: This document has been prepared to assist IEEE 802.22. 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 802.22. Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures http://standards.ieee.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 Chairhttp://standards.ieee.org/guides/bylaws/sb-bylaws.pdf Carl R. StevensonCarl R. Stevenson 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 802.22 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at patcom@iee.org.patcom@iee.org >

2. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 2 Abstract This document is to provide a suggested remedy to resolve comments related to inter-cell communications

3. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 3 Abstract (cont’d) This presentation describes a Multi-Channel Coexistence Beaconing Protocol (CBP) that allows efficient, scalable, and backward-compatible inter-cell communications for IEEE 802.22 systems. These techniques include 1) Conference Channel 2) Slotted CBP Window 3) Channel Hosting 4) Anchor CBP Window 5) CBP Window Breathing 6) CBP Window Framing 7) Modulo Scheduling of Channel Hosting

4. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 4 Co-channel CBP – the state of the art WRAN cells on the same operating channel can transmit or receive CBP packets during the synchronized CWs using the best effort contention-based protocols to communicate with one another. Analogy: Professors share the same office and discuss with one another

5. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 5 Multi-Channel CBP – an issue to be resolved Multiple requirements to communicate among neighboring cells that are operating on different channels: –Sensing quiet period coordination; Spectrum sharing coordination. Similar to the single-channel CBP operation, during a CW, the CBP-participating CPEs of a WRAN can either stay on their operating channel or tune to another channel occupied by a neighboring WRAN cell. Communications between two neighboring cells can succeed only when at least two CBP-participating CPEs from each cell are tuned to the same channel during a CW where one of them is transmitting and the other is receiving.

6. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 6 Multi-Channel CBP: the problem An analogous problem: University professors visit one another’s offices in a non-deterministic manner (asynchronously).

7. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 7 Multi-Channel CBP using a common Conference Channel Analogy: Professors meet together in an well agreed office of one of the professors.

8. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 8 Multi-Channel CBP using a common Conference Channel (cont’d) The Conference Channel is the communication channel selected by the neighboring WRAN cells in order to exchange coexistence information efficiently. To ensure efficient inter-cell communication, the neighboring WRAN cells should communicate with one another using the Conference Channel. Every single channel occupied by a WRAN cell can be selected to be the Conference Channel.

9. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 9 Slotted CBP Window Instead of being utilized as contention windows, CBP windows are slotted. Each slot is one OFDMA symbol. A typical size of a slotted CBP window is 3 slots. The advantage of CBP Window Slotting is to enable efficient management of CBP communications.

10. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 10 Channel Hosting To facilitate channel discovery and multi-channel CBP management Every channel occupied by WRAN shall have a Hosting CBP packet transmitted periodically in one of the CW slots by a WRAN cell that occupying the channel. The selected slot for Channel Hosting on a specific channel (the Hosting Slot) shall be well-known to all WRAN cells so that channel discovery becomes easy. The well-known position of the Hosting Slot can be determined by Modulo Scheduling. For example, Slot Number == Channel Number mod (16x3).

11. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 11 Channel Hosting (cont’d) Analogy: Every professor schedules a weekly office hour in which he stays in his own offices and announces his existence.

12. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 12 Anchor CBP Window To enable efficient and backward compatible channel discovery and other management tasks (such as CBP based ranging and geo- location support). The “Anchor CW” is the base CW that shall be scheduled at the end of every frame by a WRAN cell on the occupying channel. Analogy: The office hours of a professor in which hosting section and discussion sections are scheduled.

13. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 13 Anchor CBP Window (cont’d) The size of an Anchor CW is typically 3 slots. There are two types of CW slots in the Anchor CW: the Hosting Slot and the Discussion Slot. A Discussion Slot (D) is a contention window and used for contention based inter-cell communication and regular WRAN system maintenance (CBP based ranging, etc.). Similar to the non-slotted CW, a WRAN during D slots can either stay on its own operating channel or tune to another channel occupied by a neighboring WRAN cell.

14. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 14 CBP Window Breathing Initially, a fixed size Anchor CBP Window is scheduled at the end of every data frame. CBP Window Breathing – the CW size can be expanded from or shrunk back to the size of the Anchor Window according to the communication demand of CBP communications. The Breathing CW is only scheduled on the Conference Channel to facilitate efficient inter-cell communication. The CBP slot that is grown on top of the Anchor CW is called the “Presentation Slot (P)”.

15. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 15 CBP Window Breathing (cont’d) The Presentation Slot is reserved for CBP transmission for a WRAN that utilized the Conference Channel for inter-cell communications. Other WRAN cells can tune to the conference channel to receive CBP packets transmitted by a WRAN during its reserved Presentation Slot. To achieve collision-free inter-cell communication

16. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 16 CBP Window Breathing for Multi-channel CBP Analogy: the professors’ meeting agenda can be revised with presentation slots and the meeting duration extended or reduced.

17. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 17 Reservation Life-time of Presentation Slot To prevent a WRAN from holding a Presentation Slot, a Reservation Life-time of the Presentation Slot shall be initialized. The reservation of the Presentation Slot of a WRAN on the Conference Channel expires at the end of a Reservation Life-time. Typically the Life-time expires at the end of a super- frame. After the Life-time is expired, the Presentation Slot of a WRAN is recycled (by the host) and size of the breathing CBP Window is reduced by 1.

18. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 18 CBP Framing CBP Framing provides a scalable mechanism for multi- channel CBP-based inter-cell communication. A CBP Frame is a group of CBP Windows in a number of consecutive data frames, and is piloted with a Host Beacon in a Hosting Slot. A CBP Frame is a logical Frame, therefore requires no modification on the Physical Layer. Similar to a regular data frame, a CBP frame consists of a MAP and the Payload. The MAP of a CBP frame is carried by the Hosting Beacon, and specifies the payload in the frame. The Payload is the CW slots scheduled by the MAP in the CBP Frame.

19. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 19 CBP Framing (cont’d) The CBP frame size (i.e. the periodicity of the Hosting slots) shall be fixed to be either 1, 2, 4, 8, or16 frames (16 frames is recommended). Analogy: the professor who hosts the meeting sets the meeting schedule and announces the meeting agenda (presentation slots and discussion slots) for the upcoming meeting period.

20. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 20 Scheduling of Channel Hosting It’s important that the Hosting CBP packets for a particular channel are transmitted and received reliably in a well-known CW slot. A simple way: schedule all Hosting CBP packets to be transmitted in a fixed Anchor Slot on all channels

21. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 21 Scheduling of Channel Hosting (cont’d) Limitations of the Fixed Slot scheduling: –Host CBP packets transmitted at the same time instant requires that at least two pairs of CBP links available between any two neighboring cells

22. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 22 Modulo Scheduling of Channel Hosting Enable conflict-free channel hosting without the limitation of the fixed-slot scheduling scheme. Based on a common reference point in time, the Channel Hosting is scheduled at Slot s == (Channel Number) mod (Modulo Factor). Modulo Factor: total number of Anchor slots in one CBP frame (possible slots can be used for scheduling of channel hosting). For a CBP frame size of 16 frames, Modulo Factor =16x3=48 The basic common reference point: the super-frame boundary

23. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 23 Modulo Scheduling of Channel Hosting For modulo factor of m, a WRAN operating on channel N can detect channel hosting on channels N+-(m-1) without transmission conflict. The examples in the next two slides respectively shows the case of having a modulo factor m=3 (a CBP frame size of one data frame) and m=6 (a CBP frame size of two frames).

24. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 24

25. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 25 Modulo Scheduling of Channel Hosting

26. doc.: IEEE 802.22-07/0244r0 Submission May 2007 Wendong Hu, STMicroelectronicsSlide 26 Conclusion This presentation describes a Multi-Channel Coexistence Beaconing Protocol (CBP) that allows efficient, scalable, and backward-compatible inter-cell communications for IEEE 802.22 systems.