1. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 1 [Simulation results on 2 or 3 repetitions of preamble structure] IEEE P802.22 Wireless RANs Date: 2007-03-12 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 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 2 Abstract In this presentation, we will show the simulation results for initial synchronization regarding the number of repetitions within frame preamble. Through the simulation results, we can find that the preamble with 2 repetitions has good performances in preamble detection and carrier frequency offset estimation.

3. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 3 TDD Frame Structure

4. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 4 CR-OFDMA PHY Simulator

5. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 5 Details of Synchronization Block

6. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 6 Algorithms of Initial Synchronization Timing synchronization –By using auto-correlation in time-domain between two received samples apart from NFFT/2 or NFFT/3 Fractional Frequency Offset Estimation –By calculating the phase at the point of optimum timing in time- domain Integer Frequency Offset Estimation –By using cross-correlation with PN sequences of NFFT/2 or NFFT/3 in frequency-domain

7. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 7 Timing Sync. using 2 Repetitions Auto-correlation of preamble with 2 repetitions

8. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 8 Timing Sync. using 2 Repetitions (Cont’d) Auto-correlation result –Acquisition range: -GI/2 ~ +GI/2

9. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 9 Timing Sync. using 3 Repetitions Auto-correlation of preamble with 3 repetitions

10. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 10 Concerns on Timing Sync. using 3 Repetitions 2048 FFT size is not divided by 3, i.e. 2048/3=682.666  =682+2/3 Therefore, preamble has 3 repetitions with timing offset of 2/3 sub-carrier spacing by birth It means that there will be no perfect repetitions in the time domain It will disturb the robust initial synchronization

11. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 11 Concerns on Timing Sync. using 3 Repetitions (Cont’d) 3 repetitions with timing offset of 2/3 sub-carrier spacing

12. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 12 Concerns on Timing Sync. using 3 Repetitions (Cont’d) 3 repetitions with timing offset of 2/3 sub-carrier spacing

13. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 13 Phase Margin in FFO Estimation

14. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 14 Simulation Conditions WRAN channel B, C Normalized frequency offset: 5.5 Symbol timing offset: 2560 samples 2K FFT, ¼ guard interval mode BPSK modulation Pilots in preamble are boosted to have equal power regardless of preamble structure

15. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 15 Simulation Results Preamble Missing Probability Mean-Squared Error of Symbol Timing Offset (STO) Mean-Squared Error of Fractional Frequency Offset (FFO) Mean-Squared Error of Carrier Frequency Offset (CFO, i.e. Fractional Frequency Offset and Integer Frequency Offset)

16. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 16 Correlation Result of Frame Sync

17. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 17 Preamble Missing Probability In the IEEE Std 802.11-1997 section 14.6.15.3, the detection is expected to be 90% accurate even in fairly good conditions

18. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 18 MSE of STO Estimate

19. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 19 MSE of FFO Estimate

20. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 20 MSE of CFO (FFO+IFO) Estimate In the IEEE Std 802.16-2004 section 8.4.14.1, CPE shall be synchronized to the BS with a tolerance of maximum 2% of sub-carrier spacing

21. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 21 Conclusions No. of repetitions Items 23Note SNR for 90% Preamble Detection -5 dB-3 dB In WRAN Channel C Estimation Range in Time-Domain -1.0  +1.0 1) -1.5  +1.5 Normalized to sub- carrier spacing SNR for 2% MSE of CFO Estimate 2 dB7 dB In WRAN Channel C, 2% of subcarrier spacing 1) Because the integer frequency offset estimation is performed in frequency-domain, the estimation range in time-domain is meaningless.

22. doc.: IEEE 802.22-07-0114-00-0000 Submission March 2007 Chang-Joo Kim, ETRISlide 22 Conclusions (Cont’d) Because integer frequency offset estimation is performed in frequency domain, the frequency offset estimation range in time-domain is meaningless Because 2 repetitions preamble has the largest phase margin (refer to slide 13), the accuracy (mean-squared error) of CFO estimation has the best performance. Because 3 repetitions preamble has the timing offset of 2/3 sub-carrier spacing by birth, all performances of initial synchronization are severely deteriorated