1. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 1 Reservation and Management of Self-coexistence Windows for Inter-cell Discovery and Communications IEEE P802.22 Wireless RANs Date: 2007-09-16 Author: 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 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 2 Abstract We identify the potential problems with the current state of the Coexistence Beaconing Protocol (CBP). We then describe a mechanism for the reservation and management of Self-coexistence Windows that enables efficient and reliable co-existence communications based on the CBP.

3. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 3 Single Channel CBP: the current state WRAN cells on the same operating channel can transmit or receive CBP packets during the synchronized SCWs using a best effort (contention-based) protocol to communicate with one another. Collisions occur when the communicating cells are all in active mode; No CBP packet is captured when they’re all in passive mode (bandwidth wasted).

4. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 4 Cross Channel CBP: the Current State Similar to the single-channel CBP operation, during a SCW, CBP- enabled stations (BS or CPE) of a WRAN can either stay on their operating channel or tune to another channel occupied by a neighboring WRAN cell (receiving only when off-channel). Communications between two neighboring cells can succeed only –When at least two CBP-enable stations from different cell are tuned to the same channel during a SCW with one of them transmitting and the other receiving. –There is no collision occurs on the channel where the CBP packet is being transmitted. The problem: it is more difficult than the single channel case to capture CBP packets cross-channel if CBP packets are transmitted in non-deterministic instances.

5. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 5 Cross-Channel CBP: the Current State (cont’d) Communication failures due to co-channel CBP packet collisions are not shown in this figure

6. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 6 Reservation of SCWs Each co-existing WRAN cell acquires (reserves) on the operating channel a sequence of SCWs that are not occupied by any other co-channel WRAN cells. The acquired SCWs are refered to as the “Presentation SCW", in which only the cell made the reservation can talk. The acquired SCWs for a WRAN cell are allocated periodically (such as every 4/8/16 frames) in deterministic instances. Consequently, all WRAN cells on the same channel will make their reservation of Presentation SCWs within the duration of one period. For example, given a period a 16 frames, cell A reserves the SCW in frame 2, cell B in frame 5, and cell C in frame 6 in a super-frame, and so on. The SCW reservation pattern is repeated periodically (according to the specified period, e.g. 16 frames). The periodic repeated SCW reservation pattern is called a “CBP Frame” (see doc: 22-07-0274-02-0000)

7. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 7 Reservation of SCWs (cont’d) WRAN 1, 2, 3, and 4 reserve respectively a SCW within a reservation period (4 frames in this example)

8. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 8 Management of SCW Reservation Simultaneous cross-channel CBP transmissions –Require at least two pairs of face-to-face neighbor-cell CPEs. –What if such condition is not satisfied? Conflicts in SCW reservation –Two or more WRAN cells try to reserve the same SCW –Would need a arbiter Latency of WRAN discovery –Need to monitor at least one SCW reservation period in order to discover all WRAN cells on a particular channel –The same latency is needed for verifying the SCW reservation (CBP transmission scheduling) of all WRAN cells on a particular channel. Flexible and scalable management of SCW reservation is desirable –Managing a mixture of reserved SCWs, contention-based (free-to-talk) SCWs, SCWs for geo-location (and other new functions), etc… –Flexible and scalable scheduling of a mixture of different SCW types…

9. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 9 Managing SCW Reservations with CBP Framing CBP Framing provides a scalable and flexible management for CBP- based inter-cell communication. A CBP Frame is a group of CBP Windows in 16 (can be 8 or 4) consecutive data frames, and is piloted with a Hosting Beacon in a Announcement SCW (residing in a particular frame in a super-frame). Similar to a regular data frame, a CBP frame consists of a MAP (payload scheduling) and the Payload. The MAP of a CBP frame is carried by the Announcement Beacon and specifies the payload in the CBP frame. The Payload is the SCWs scheduled by the MAP in the CBP Frame (a series of 16 data frames). A CBP frame is a logical concept and needs no modification on the PHY.

10. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 10 CBP Framing

11. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 11 CBP Framing (cont’d)

12. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 12 Types of SCWs in a CBP Frame Announcement (hosting) SCW (H) –Reserved for the transmission of the Hosting CBP packet. –It is always at the beginning of a CBP frame. –Aggregating information of SCW scheduling (MAP) and other information facilitating efficient WRAN discovery. Presentation (reservation) SCW (P) –Reserved for a WRAN cell to perform contention-free CBP packet transmission –Other WRAN cells can received the packet during this slot. –Each WRAN cell can reserve its own P slot. Discussion (contention/free-to-talk) SCW (D) –Used for contention-based inter-cell communication and regular WRAN system maintenance (CBP based ranging, etc.). –Ensure backward compatibility with the current CBP mechanism.

13. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 13 Scheduling of SCWs in a CBP Frame P(x): Reserved Presentation Slot for CBP transmission of WRAN cell x.

14. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 14 Reservation Life-time of Presentation Slot To prevent a WRAN cell 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 a Channel expires at the end of a corresponding Reservation Life-time. Typically the Life-time is a (to be defined) number of super- frames. After the Life-time is expired, the Presentation Slot of a WRAN is removed.

15. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 15 Cross-channel Inter-cell Communication WRAN cell “A” to receive CBP packets from a nearby WRAN cell “B” –Tune to the operating channel of WRAN B – Ch(B) – during the hosting slot of Ch(B); –Receive and decode the CBP frame MAP of Ch(B) – H(B); –Identify the presentation slot of WRAN B – P(B); –If P(B) exists, receive CBP packets from WRAN B at slot P(B); –Else, try to receive CBP packets from WRAN B during the discussion slots on Ch(B) WRAN cell “A” to transmit CBP packet to a nearby WRAN “B” –If presentation slot is required for the CBP packet transmission, reserve one – P(A). –Transmit the CBP frame MAP – H(A) – on its operating channel – Ch(A) – during the hosting slot of Ch(A); –If there is presentation slot – P(A) – reserved for WRAN A, transmit the CBP packet during P(A); –Else, transmit the CBP packet during the discussion slot on Ch(A). Note – co-channel inter-cell communication is a special case of cross- channel communication, therefore the same protocol applies.

16. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 16 Cross-channel Inter-cell Communication

17. doc.: IEEE 802.22-07/0455r0 Submission September 2007 Wendong Hu, STMicroelectronicsSlide 17 Conclusion SCW Reservation and SCW management with CBP Framing –Reliable, collision-free CBP communications; –Efficient discovery of WRAN cells on a large set of channels One deterministic SCW is for discovering all WRAN cells on one channel. A sufficiently large set of channels can be discovered in just one super-frame. –Efficient and flexible management of CBP communications Enable conflict-free SCW reservations Efficient and flexible Management of a mixture of different SCW operations –Reserved SCWs (for collision-free talk), –Contention-based (free-to-talk) SCWs, –SCWs for CBP-based ranging (and other additional functions) Flexible and scalable scheduling of a mixture of different SCW types –Flexible and scalable pattern of SCW scheduling. –No fixed pattern required.