1. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 1 Interference-free CPE Scheduling (Comments #131, #149, and #150) IEEE P802.22 Wireless RANs Date: 2008-11-09 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 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 2 Interference-free CPE scheduling WRAN Self-coexistence considerations Spectrum Etiquette Interference-free scheduling Adaptive on-demand channel contention Dynamic resource renting/offering Different TV channel selection Frame allocation signalled by the Superframe Control Header (SCH) MAC self-coexistence schemesPHY coexistence mechanisms New

3. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 3 WRAN Self-coexistence considerations The 802.22 WRAN standard needs to allow for coexistence of overlapping co-channel cells with proper capacity sharing to avoid abrupt system failure caused by ‘self-interference’ This new self-coexistence mode will need to be as efficient as possible while allowing for adaptive channel capacity allocation among co-channel WRAN cells Capacity will be allocated to overlapping cells on a frame basis and signalled by the SCH for the next 16 frames of the superframe Coexistence scheme should allow for concurrent transmission of frames if these frames are not directed to CPEs in overlap areas (collisions would occur in overlap area but the traffic is not destined to these CPEs) Interference-free scheduling is to allocate capacity to the right CPEs to reduce collisions and maximize frame concurrence

4. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 4 Impact of interference-free CPE scheduling BS1BS2 Distance between BS’s 100% 50% Capacity per BS 0% with interference- free scheduling without interference- free scheduling

5. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 5 Inter-frame capacity allocation The Superframe Control Header (SCH) will carry information about: 1)the frame allocation to the various ovelapping WRAN cells 2)the location of the inter-frame and intra-frame quiet periods, and 3)the location of the Self-Coexistence Windows (SCW) The frame allocation could be signalled by a 16-bit pattern per overlapping WRAN cell: –Since a superframe contains 16 frames, the number of overlapping WRAN cells in one area that could be accommodated if a minimum of one frame per superframe is to be assigned for each BS is 16 –In practice, less than 16 cells are likely to mutually overlap in one area but interdependency may involve a large number of cells (e.g., ring of 16 cells that partially overlap with each other) –16 overlapping cells seems to be a reasonable cluster size

6. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 6 Inter-frame capacity allocation (Cont’d) Minimum pace for frame multiplexing: –To keep time sync at the CPE: minimum one per superframe –To provide QoS: every two frames but not practical => compromise on QoS will be needed in self-coexistence situation: “best effort” The output of the MAC coexistence algorithms will be the assignment of the 16 frames in a superframe to the local co-channel overlapping BSs based on their claims: –special QoS requirements for specific applications, e.g., trPS, nrtPS, BE (see section 6.9.8.10.11 Service Flow Scheduling Type) –their respective capacity loading (based on most critical CID stack size at BS and/or CPE) –whether the frame to be transmitted is addressing CPEs where no objectionable frame collision will occur or CPEs in overlap areas (i.e., the mutual BS incompatibility for each frame)

7. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 7 Inter-frame capacity allocation (Cont’d) Example

8. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 8 Self-coexistence capacity allocation scheme The capacity allocation scheme will include frames that can be transmitted concurrently by non-overlapping WRAN cells as well as cells that are overlapping if the traffic carried during these frames address CPEs outside the overlap areas. –Collisions would occur in the overlap areas but no CPE would be listening in those areas since it is not addressed to it. When the traffic is directed to CPEs in an overlapped area, only one of the overlapped WRAN BSs will be allowed to transmit during a given frame to avoid frame collision at the CPE in the downstream and at the BSs in the upstream. It will be very important to precisely identify the CPEs in the overlapped areas to maximize the transmission capacity –A method to precisely quantify the state of WRAN cells’ overlap at each CPE based on RSSI is proposed in 22-08-0137-03-0000-wran- coexistence-considerations.ppt

9. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 9 Frame incompatibility table at BS3 This Table will be generated at each BS and include all CPEs associated with it (e.g., BS3) that will be affected by transmissions from other specific BSs. –An incompatible CPE is added to the Table if the difference between the RSSI of the desired BS and that of the undesired BS is less than x dB depending on the modulation used for the communication. When a BS needs to communicate with one of these CPEs, an incompatibility flag will be included in the 16 bit array that will be transmitted in the CBP burst exchanged among BSs so that concurrent frame transmission is avoided by the two BSs involved. BS1BS2BS3BS4BS5… BS3CPE1 CPE4 CPE7 -(void)CPE5 CPE8 CPE5 CPE7 CPE8

10. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 10 Self-coexistence capacity allocation scheme Frame capacity will be assigned among overlapping cells based on a distributed algorithm operating at each BS Information on the capacity loading of each BS and special QoS requirements will be transmitted among BSs through the CBP burst Each frame request from each overlapping BS will be accompanied with the 16-bit incompatibility array depending on the CPEs served by this frame so that concurrent frame transmissions are avoided by the specific incompatible BSs involved Based on this information, all BSs will develop a common frame assignment that will be signalled by the upcoming SCH broadcast by all BSs for the coming superframe Note: The signalling among BSs will need to transmit sufficient information within the given time frame (a superframe) to make sure that all the algorithms at all BSs converge on the same frame scheduling.

11. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 11 Self-coexistence capacity allocation scheme Capacity loading for the critical CID (stack size) Most critical service flow scheduling (rtPS, nrtPS, BE, …) 16-bit incompatibility array Frame scheduling for the upcoming superframe transmitted in the SCH by the 16-bit pattern for each BS Interference-free scheduling Adaptive on-demand channel contention Dynamic resource renting/offering Scheduling of non-concurrent probing frames Self-coexistence capacity allocation algorithm at each BS Interference-free scheduling Adaptive on-demand channel contention Dynamic resource renting/offering Scheduling of non-concurrent probing frames Self-coexistence capacity allocation algorithm at each BS Interference-free CPE scheduling Dynamic resource renting/offering Adaptive on-demand channel contention Scheduling of non-concurrent probing frames Self-coexistence capacity allocation algorithm at each BS Inter-BS communication using the CBP bursts Information to be exchanged among all overlapped BSs in preparation for the next 16-frame capacity allocation Information to be transmitted by all overlapped BSs in their superframe header For each frame requested by each BS

12. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 12 Exchange of information among BSs for self-coexistence A sufficient number of Self-Coexistence Windows (SCW) will need to be allocated per superframe to exchange the information necessary to make sure that the distributed capacity allocation algorithms in each BS always converge to a common frame allocation for the upcoming superframe Transmission mechanism: Coexistence Beacon Protocol (CBP) burst Note: Transmission of the SCH content of the next superframe may be needed to confirm that it is common to all BSs in the cluster. Not needed if convergence at each BS is reliable enough.

13. doc.: IEEE 802.22-08/0307r0 Submission November 2008 Gerald Chouinard, CRCSlide 13 Conclusion Interference-free CPE scheduling is needed to maximize the channel capacity by allowing concurrent frame transmission in case of partially overlapping WRAN cells when addressing CPEs outside the overlap area The MAC section needs to be modified for the right information to be transmitted by the CPB bursts Distributed frame scheduling among BSs will need to operate fast with its inter-BS communications taking place in the previous superframe so that the new schedule can be broadcast in the upcoming superframe header At least one feasible distributed frame allocation algorithm needs to be demonstrated for feasibility and documented At least one example of a feasible exchange of information among a group of overlapping BSs using the CBP burst needs to be demonstrated and documented