1. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 1 On-demand EOBS for hidden incumbent reporting IEEE P802.22 Wireless RANs Date: 2006-06-15 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 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 2 Abstract We propose an extension to the EOBS (Explicit Out- Band Signaling) scheme so that the out-band signaling is turned on only upon occurrence of the hidden incumbent situation. This is to avoid periodic out-of- band broadcast in candidate channels. Thus, candidate channels could be used for other purposes.

3. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 3 Content Overview of the hidden incumbent situation Overview of the EOBS scheme On-demand EOBS Calculation on signaling overhead saving

4. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 4 Overview of the hidden incumbent situation (1/2) Incumbent receivers are not interfered by BS CPEs in the dot-shaded region are interfered by the incumbent transmission BS cannot detect the incumbent transmission directly CPEs in the slash-shaded region are able to detect and report the incumbent transmission Incumbent Rx (incumbent receivers are located inside this contour) BS/CPE Rx BS/CPE Sensing Incumbent Tx Incumbent Rx CPE Rx BS Tx Affected CPEs (interfered by incumbent transmission) Normal detection region No interference to incumbent receivers

5. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 5 Overview of the hidden incumbent situation (2/2) Incumbent receivers in horizontal-line-shaded region are interfered by BS CPEs in the slash-shaded region are able to detect and report the incumbent transmission, but if this region is small as shown there might not be any CPE in this region, and the incumbent receivers continue to be interfered by the BS BS/CPE Rx BS Sensing Incumbent Rx CPE Rx BS Tx Affected CPEs Incumbent receivers interfered by BS Normal detection region Incumbent Tx Incumbent Rx (incumbent receivers are located inside this contour) Interference to incumbent receivers

6. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 6 Overview of the EOBS scheme BS to transmit control messages in several out-of- operating-bands (“out-bands”) periodically: –When a CPE finds that it loses synchronization with the BS, and that it sensed an incumbent transmission (“affected CPE”), it looks for the out-band broadcasts to gain synchronization and then send the report The EOBS proposal defines these functionalities: –Searching and synchronizing to an out-band channel upon hidden incumbent detection –Method of acquiring uplink resource for sending report, e.g. pre- assigned US resource during network entry, or by contention –Report format

7. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 7 On-demand EOBS To reduce the signaling overhead of periodic transmission of out-band broadcasts, we propose to turn on EOBS only on-demand The BS is signaled by the affected CPEs to turn on the out-band broadcasts (EOBS) in this way: –The affected CPEs send out a special tone in one of the unused channels (list as specified by BS) –The BS picks up this signal during its out-of-band sensing. Upon detecting that it is the special tone, the BS turns on EOBS. EOBS takes over from here –The affected CPEs will switch off after a timeout if they do not hear the EOBS broadcast EOBS is switched off after BS makes decision in response to the report If there is no unused channel, the tone is sent in-band. The BS picks up the signal during in-band sensing. In this case EOBS is not turned on, the BS has to make decision without detail report

8. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 8 On-demand EOBS (at the CPE)

9. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 9 On-demand EOBS (at the BS)

10. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 10 Calculation on signaling overhead saving Number of candidate channels = x Mean arrival rate of a hidden incumbent = a Broadcast message time length = c Inter-EOBS broadcast time = s Average tone duration before EOBS is turned on = b Average total signaling time from arrival of an hidden incumbent to transmission of report for EOBS and OD-EOBS = t EOBS, t OD-EOBS

11. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 11 Calculation on signaling overhead saving If x = 3, c = 10ms, s = 1s, a = 1/day, b = 1s, overhead_saving = 99.96%

12. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 12 Discussions Why not just transmit the special tone in-band in all cases? –If unused channels are available, transmitting the special tone out- of-band will not disrupt ongoing WRAN communications, and of course will not cause interference to the incumbent users Do we need to maintain a second channel? –Maintaining a second channel is akin to running the WRAN in channel aggregation mode. If a WRAN is to operate in channel aggregation mode the hidden incumbent report can be easily sent in the other operating channels –If a WRAN operates only in one channel, then there is no need to maintain a second channel. The WRAN will switch to another channel upon detection of an incumbent

13. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 13 Discussions The occurrence of a TV hidden incumbent is rare –This is the reason why we propose to make EOBS out-of-band broadcasting on-demand Wireless microphone transmission might not cause a nearby CPE to lose synchronization with the BS, because the BW is small compared to a full TV channel –Wireless microphone BW of 200kHz will affect about 60 subcarriers (200kHz/(6MHz/2048) = 68.3). And this may affect many subchannels if distributed subcarrier allocation is used. This can affect part of the frame preamble and DS/US MAPs and may eventually affect synchronization

14. doc.: IEEE 802.22-06/0099r1 Submission June 2006 Ang Chee Wei, Institute for Infocomm ResearchSlide 14 Proposal Text Change Add text to existing section 6.16.4.1 to help explain the hidden incumbent situation in greater detail. Add a new subsection “6.16.4.3 On-Demand EOBS” to describe the scheme that activates EOBS on demand.