1. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 1 MAC Management Message for Efficient Sensing With Supplements on Pages 17 – 22 (June 08) IEEE P802.22 Wireless RANs Date: 2006-06-01 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 Authors:

2. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 2 Co-Authors:

3. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 3 MAC Management Messages for Efficient Sensing

4. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 4 Outline Motivation: WRAN: limited resource for sensing More sensing resource (sensing period and number of sensing CPEs) should be allocated to “urgent” channels To facilitate this, BS needs to specify discontiguous channels for CPE to sense Three parts: I.The need to specify the discontiguous channels (Why “urgent”?) What do we mean by “urgent” Why some channels are more “urgent” than the others Why those “urgent” channels can be discontiguous II.The proposed changes to existing MAC messages (“Channel list”) III.Simulation results

5. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 5 Why “urgent”? --- example 1 What are “urgent” channels? –“Urgent” channels are those that requires considerably more resources to perform reliable sensing –Some channels are more “urgent” than others since the density of CPEs is not uniform in the cell. Some region requires more resource to detect incumbents –E.g.: Incumbent detection at proximity of CPE1 is more difficult due to low local CPE-density. –Since Channel A is being used by CPE1 but CPE1 alone is not efficient enough to sense the Channel A reliably, it is more urgent than Channels B and C.

6. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 6 Why “urgent”? --- example 1 What if insufficient resource is allocated to sensing Channel A? –Either the detection capability of incumbent presence is unsatisfactory, or –System false alarm rate is too high –E.g. One system false alarm leads to 10 minutes prohibited use of Channel A. P dec = 0.9, P false = 0.1, T detect = 2sec false alarm per minute = (1-0.9^(60/2)) = 96%  a false alarm will trigger 10-minutes Non-Occupation Period.  Channel can hardly be used.

7. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 7 Why “urgent”? --- example 1 Solution: –Allocate more CPEs to spend more periods sensing urgent channels. (e.g. assign CPE 2-4 to help CPE 1 to sense Ch A) Urgent channels change dynamically and generally will not appear contiguous. The BS needs to have efficient mechanism to specify discontiguous channels for CPEs to sense.

8. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 8 Why “urgent”? --- example 2 Channels 3, 4, and 5 are less “urgent”, probably due to –TV signals present (database or site survey) –Temporarily strong incumbent signal (e.g. TV station’s remote -news van) Difference between “channel aggregation” –CPE shall not only sense the channels it is using, but need to sense channels used by some other (but may not be all) CPEs and channels not used by the cell.

9. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 9 A flexible and efficient sensing scheme is needed for BS to specify discontiguous channels for the CPEs to sense. The current spec imposes a severe overhead punishment on the deployment of such schemes.

10. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 10 Proposed changes --- “channel list” Current Bulk Measurement Request SyntaxSize BLM-REQ_Message_Format() { Management Message Type = 398 bits Transaction ID16 bits Starting Channel Number8 bits Number of Channels8 bits Confirmation Needed1 bit Number of Single Measurement Requests 3 bits Single Measurement RequestsVariable } Proposed Bulk Measurement Request SyntaxSize BLM-REQ_Message_Format() { Management Message Type = 398 bits Transaction ID16 bits Interval-basis Channel ListVariable Confirmation Needed1 bit Number of Single Measurement Requests 3 bits Single Measurement RequestsVariable }

11. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 11 Proposed changes --- “channel list” SyntaxSizeNotes Interval_basis_Channel_List_Format () { Starting Channel Number8 bitsThe index of the starting channel Number of Channels8 bitsThe number of channels in the current interval Linker1 bit1: The next 17 bits follow the interval-basis structure 0: The Channel List structure is terminated here } Interleaved-based channel list* * The Beacon Measurement Report and Consolidated Spectrum Occupancy Measurement Report should also be changed accordingly, please refer to our report for the details. Same as original scheme Only one bit overhead is added even if the channel is contiguous

12. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 12 Simulation result

13. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 13 Simulation result

14. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 14 Simulation result

15. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 15 Simulation result

16. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 16 Conclusion We have proposed a flexible and efficient “channel list” structure to reduce the overhead for the BS to specifies discontiguous channels for CPEs to sense. Significant overhead savings have been shown through the numerical results.

17. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 17 As per our proposal one-bit overheadonly contiguous (a) an one-bit overhead when only contiguous channels are sensed; save hundred of bitsdiscontiguous (b) save hundred of bits when discontiguous channels are sensed. An Example Scenario of Discontiguous Channels [1]CPEs need to do in-band sensing; [2]BS holds a backup channel list and it askes CPEs to sense these channels [3] In order to avoid adjacent channel interference, the channels in the backup list should be as far away from the current channel as possible (this is mentioned in page 167 of Draft v0.1)  It is very possible that CPEs need to sense discontiguous channels Supplement: Summary & Example

18. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 18 Supplement: Comments & Technical Difficulties Comments: Simulations should be performed to figure out how often (a) and (b) appear in WRAN systems. Technical DifficultiesTechnical Difficulties how likely deployment, probability distribution  It is almost not possible to simulate how likely a system will have discontiguous channels for sensing. It is because it depends on deployment, probability distribution that the number of discontiguous channels occur, and the like. implementation-specific / vendor-dependent issues sensing scheduling, sensing algorithm  Given a particular sensing list of discontiguous channels, there are a lot of implementation-specific / vendor-dependent issues that are not well- defined, such as sensing scheduling, sensing algorithm, and the like. Our concern is how we can figure out our conjecture / guess on some parameters such that all members can feel that these make sense.

19. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 19 Simulations are performed based on our example scenario. Consolidated Spectrum Occupancy Measurement Report (CSOMR): – Periodic Transmit from CPE to BS, we shall study the average overhead per transmission. Beacon Measurement Request : – May not need periodic transmission, event driven instead. When some incumbents appear in the sensing channels, BLM_REQ is transmitted. Assumptions: –Suppose CPE can sense N channels (CPE Sensing Capability): one in-band sensing and (N-1) out- band sensing channels selected from backup channels –TV channels are randomly distributed –Part 74 incumbents appear with a probability P in each channel –The CPE report once 2 seconds –The BS sends the BLM_REQ when any of the reported sensing channels is blocked –Presence state of Part 74 incumbents in each channel slowly changes: the probability of an incumbent user detected in the channel which is clean in last report is P_chg. Supplement: Simulation Settings

20. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 20 Supplement: Simulation Results – CSOMR Figure 1 Figure 2 Total Channels: 100 CPE Sensing Capability: 10 Total Channels: 100 Number of channels occupied by incumbent users on average: 50

21. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 21 Supplement: Simulation Results – BLM_REQ (1) Figure 3Figure 4 Total Channels: 100 CPE Sensing Capability: 10 P_chg: 0.1 Total Channels: 100 Number of channels occupied by TV stations on average: 50 P_chg: 0.1

22. doc.: IEEE 802.22-06/0084-02-0000 Submission June 2006 Jianwei Zhang, Huawei Slide 22 Supplement: Simulation Results – BLM_REQ (2) Figure 5 Total Channels: 100 Number of channels occupied by TV stations on average: 50 CPE Sensing Capability: 10