1. Preamble and Cell Search Design for 802.16m System IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE S802.16m-08/470r1 Date Submitted: 2008-05-05 Source: Mingyang Sun, Yunsong Yang, Xueqin Gu, Chongli Liu, Xin Chang E-mail: xin.chang@huawei.com Huawei Venue: IEEE 802.16 Session #55, Macao, China Base Contribution: IEEE C802.16m-08/470 Purpose: For discussion and approval by IEEE 802.16 Working Group Notice: This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who 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 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. Outline Requirements for Cell Search Proposed preamble features Structure of the super-frame header Synchronization Sequences Design Simulation Results

3. Requirements for Cell Search Fast system access, support fast cell select and reselect; Good cell detection performance; Low overhead; Low complexity; Support large cell average; Large cell ID set to support femto cell and Relay station; Support multi-bandwidth; Support CP detection; Low PAPR; Support multi-carrier fast handover; Assistant channel measure; Assistant channel estimation; Support MIMO;

4. Why do we need new preamble? System access latency –16e preamble can not support fast system access System access latency: 300ms B3G system desired value: 20-80ms and below Cell coverage –16e preamble PAPR is not enough low 3.65~4.36dB –16e preamble cross-correlation is not enough good –Sector specific 16e preamble sequence limit cell edge MS system access performance In cell edge the property of repetition of 3 is destroyed MS capability support –16e preamble can not support different capability MS access pure 16m system support MIMO support

5. Proposed preamble features Low PAPR sequence and larger cell coverage –PAPR is almost 0 dB –Good cross correlation Large cell ID set than 16e to support femto cell and Relay station 16e: 114 Proposed scheme: 417 Low cell search time and complexity –300ms->20ms –Simple cell detection algorithm and one FFT operation can detect multiple cell IDs –Proposed sequence provide better cell detection performance –Same OFDM waveform on P-SCH in all cells –Coarse time synchronization in time domain –Hierarchical SCH structure P-SCH and S-SCH

6. 16m super frame header location

7. The super frame header is transmitted one or more times every 20 ms super frame –The transmission period of SCH and BCH may be different Different level of error protection –preamble is placed in DL last sub frame The interval between 16m preamble and 16e preamble is fixed The SCH and BCH is transmitted only in the central part of the overall transmission band of the cell –Enable bandwidth Identification –Enable multi-bandwidth MS access Fixed CP length on P-SCH and S-SCH and specific preamble structure –Enable CP Identification

8. Multiplexing of SCH and BCH The multiplexing of P-SCH and S-SCH is TDM –The design provides enough power to guarantee cell search performance The multiplexing of SCH and BCH is TDM The multiplexing of P-BCH and S-BCH is TDM –If the system bandwidth is big enough, the retaining bandwidth may carry other data or control channel

9. Purposes of the 16m preamble P-SCH –Same OFDM waveform in all cells –Used for SCH symbol timing and frequency acquisition S-SCH –Cell specific OFDM waveform –Used for determining the cell ID P-BCH –network-wide common and Static system parameter and information to decode S-BCH –CP length, DL/UL FFT size, S-BCH frequency reuse indication, S-BCH location, S-BCH hopping seed, antenna configuration information S-BCH –Cell specific system parameter

10. CP Identification CP length is fixed for the OFDM symbols carried P- SCH and S-SCH –Enable CP Identification –After decoding P-SCH and S-SCH, P-BCH is decoded and CP length information is acquired

11. Transmit diversity for SCH and BCH transmission P-SCH and S-SCH –the CSD transmission interval is same as the CP length P-BCH Default: STBC/SFBC/Co-STBC/Co-SFBC (Matrix A) Optional: CDD 、 PSD 、 TSTD 、 FSTD S-BCH Default: STBC/SFBC/Co-STBC/Co-SFBC (Matrix A) Optional: CDD 、 PSD 、 TSTD 、 FSTD

12. Synchronization Sequences Design

13. Preamble Transmission Structure After P-SCH sequences and S-SCH sequences are generated, P-SCH and S-SCH sequences firstly are processed with DFT operation and then are mapped on sub- carriers.

14. Non-CAZAC SCH sequence The proposed synchronization sequences are based on a particular sequences The proposed sequences have very low PAPR (lower than the PN sequence based 16e preambles) and better cross correlation in frequency domain between any pair of the sequences Specific and simple cell detection algorithm to provide better cell detection performance

15. Sequence definition The P-SCH sequence is defined: The S-SCH sequences are defined: NG is desired sequence length The integer “u” is referred to as class index – A different “u” will also act as a cell ID

16. The P-SCH and S-SCH are transmitted only on the central part of the overall transmission band of the cell Because sequence inherent characteristic, SCH time domain sequence is composed of two repeated sequences though SCH is transmitted on continuous subcarriers Better performance because longer sequence Larger cell ID set Low cell search time Coarse time synchronization in time domain SCH sequence sub-carrier mapping

17. S-SCH –Scrambled by 2 bits LSBs of frame index and P-SCH sequence Determine the superframe boundary Determine the frame in which P-BCH is carried in despite of transmission period of SCH and BCH P-BCH carries all the bits of system time These two bits can also be used to seed PHY algorithms like hopping/scrambling etc P-BCH –P-BCH is scrambled by SFN ID S-BCH –Scrambled by Cell ID P-SCH –when only P-SCH is present, P-SCH is scrambled by 2 bits LSBs of frame index. Scramble for SCH and BCH

18. Fast cell search process Obtain time and frequency synchronization; Take N-point FFT to the receives data to get the frequency domain data at N G sub-carriers; denote the N G frequency data with Y(m), m=1,…, N G ; The peak position n max of Y(m) gives information about u: The identified u is the integer closest to calculated by the above formula;

19. System Acquisition Procedure

20. Simulation Assumptions This section provides several simulations to illustrate the performance of the proposed synchronization sequences. The simulation parameters are set as in Table 1. Carrier frequency2.5GHz Sub-carrier spacing10.94kHz Channel modelPB3, VA30 System bandwidth10MHz P-SCH bandwidth5MHz (420 sub-carriers) S-SCH bandwidth5MHz (420 sub-carriers) Power boostno CP length128 Cell ID number417

21. Their PAPRs of all 417 sequences are almost 0dB, i.e. almost constant amplitude. Noted the sequence index is the number of sequences. PAPR

22. Coarse Search with proposed sequence

23. frequency offset≤2% of the sub-carrier spacing at 0 dB in the case of no power boost Decimal FO Estimation with proposed sequence

24. Integer FO Estimation with proposed sequence

25. Fine Search with proposed sequence

26. One FFT can separate multiple cells ID VA30, SNR=-2dB, proposed sequences cell detection performance (200 Monte-Carlo simulation)

27. PB3, SNR=-2dB, proposed sequences cell detection performance (200 Monte-Carlo simulation)

28. False alarm probability