1. 1 Proposal of the UL Pilot Pattern IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: IEEE C802.16m-08_977 Date Submitted: 2008-09-05 Source: Sungho Park, Bin-chul Ihm, Jinsoo Choi LG Electronic Inc. E-mail : {Park_SH, bcihm, emptylie}@lge.com Venue: TGm call for comments on IEEE 802.16m-08/003r4. Specific topic : “UL Pilot scheme” Base Contribution: N/A Purpose: To be discussed and adopted by TGm 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. 2 Introduction ◙Baseline  This contribution only treats the pilot structure on 6x6 tile  The simulation is based on documents C80216m-UL-PHY-08-003r6 and C80216mUL-PHY-08-018 ◙Evaluation points  Goodput / PER comparison between various pilot patterns  Consideration on frequency offset  Consideration on power limited environment ◙Performance Metric  Goodput / PER

3. 3 Simulation Parameters (1) ◙System Parameters  Link Type : Open-loop  Channel Model & Mobility Ped B (3km/h) Veh A (120km/h)  Modulation & Channel Coding Channel Coding : Turbo Code (R=½, ¾) Modulation Order: QPSK, 16QAM  Channelization LDRU (1 LDRU = 18 Subcarriers x 6 OFDMA Symbols) Data Allocation : 2 LDRUs  Frequency Offset : max. 2% of subcarrier spacing ◙MIMO Parameters  # of Transmit Antenna : 2  # of Receive Antenna : 2  MIMO Scheme : SM  Channel Estimator : 2-D WIENNER  MIMO Receiver Type : MMSE

4. 4 Simulation Parameters (2) ◙Pilot Structures  Pilot Boosting Level : 3dB (Pilot Only Boosting)  Group A Per Stream Pilot Density : 11.11% Related Contributions : LGE, MediaTek (New)  Group B Per Stream Pilot Density : 11.11% Related Contributions : Huawei, Intel, Cairo University, Wicreo, MeidaTek (Old) [Pattern A1][Pattern A2] [Pattern B1][Pattern B2]

5. 5 Simulation Parameters (3)  Group C Per Stream Pilot Density : 11.11% Related Contributions : NSN, Nortel [Pattern C1][Pattern C2]

6. 6 Link Performance – Goodput (1)

7. 7 Link Performance – Goodput (2)

8. 8 Link Performance – PER (1)

9. 9 Link Performance – Frequency offset (1) ◙Frequency Offset : 2% of subcarrier spacing per MS [-0.02, 0.02] A1A2B1 Pilot collision region due to frequency offset  Pilot power boosting problem  2% frequency offset doesn’t induce significant performance loss

10. 10 Link Performance – Frequency offset (2)

11. 11 Link Performance – Limited Total Tx Power (1) ◙Problem for Concentrated Pilot Subcarriers  In case of pilot structures in Group C, one OFDMA symbol has 6 pilot tones per stream in a LDRU.  This structures cause large symbol power fluctuation when pilot power is boosted.  In limited Tx power environment, it can be significantly affected by some methods such as back-off / clipping / data power stealing, etc [Concentrated pilot][Separated pilot] pilot overhead = 66.67% pilot overhead = 33.33%

12. 12 Link Performance – Limited Total Tx Power (2) [Pilot only boosting case]  Performance of pilot structure C1 is closed to A1 [Transmit power limited]  Performance of pilot structure C1 is decreased significantly due to relative lower data power rather than A1

13. 13 Conclusion ◙Pilot structure Summary  In our simulation results, B1 pilot structure outperforms than others for all cases and the next is A1.  Even though A2 pilot structure has similar to A1, it has lower channel estimation performance in selective fading environment due to different pilot offset per antenna.  A2, B2, C1 and C2 have lower performance. Because these have concentrated or leaning to one side pilot position.  Moreover, if pilot tones don’t disperse through OFDMA symbols such as pilot structure group C, the power efficiency goes down as if data power is lower relatively (  symbol power fluctuation problem).  Additionally, we verify the performance loss due to frequency offset. In our results, when the offset is assumed as maximum 2% of subcarrier spacing, the effect is negligible. Therefore, it is unnecessary that pilot structure should be optimized to avoid collision.

14. 14 Proposed SDD Text Insert the following into SDD Section 11.6.3 in IEEE 802.16m-08/003r4 11.6.3 Pilot Structure 11.6.3.1 Pilot Structure for 6x6 Tile of LDRU