PHY Structure for UL Fast Feedback Channel in 802.16m Systems IEEE 802.16 Presentation Submission Template (Rev. 9) Document Number: C80216m-08/1037 Date Submitted: 2008-09-05 Source: Chih-Yuan Lin (chihyuan.lin@mediatek.com), Pei-Kai Liao (pk.liao@mediatek.com ), Yu-Hao Chang (yuhao.chang@mediatek.com), Ciou-Ping Wu (ciouping.wu@mediatek.com), and Paul Cheng (paul.cheng@mediatek.com) MediaTek Inc. No.1, Dusing Road 1, Science-Based Industrial Park, Hsinchu, Taiwan 300, R.O.C. Re: PHY: SDD Session 56 Cleanup; in response to the TGm Call for Contributions and Comments 802.16m-08/033 for Session 57. Base Contribution: This is the base contribution Purpose: Propose to be discussed and adopted by TGm for the use in Project 802.16m SDD 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: <http://standards.ieee.org/guides/bylaws/sect6-7.html#6> and <http://standards.ieee.org/guides/opman/sect6.html#6.3>. Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and <http://standards.ieee.org/board/pat >.

Outline Introduction Proposed UL control tile Analysis results Conclusion Text proposal

Introduction UL control channel types CQI feedback channel Precoder matrix index (PMI) feedback MIMO mode selection ACK/NACK channel This contribution focuses on UL fast feedback channel, which includes above feedback channels except ACK/NACK UL fast feedback control tile Corresponding pilot pattern

UL Control Tile (1/2) Considerations of determining UL control tile UL tile size should be multiple of UL control tile Convenient to partition control and data channels in a subframe No data tones would be wasted Tile size Since CQI is in general small information, tile size should not be too large Smaller tile size can provide larger frequency diversity gain

UL Control Tile (2/2) Proposed control tile Pilot location Two subcarriers and six OFDM symbols Other sizes are FFS Pilot location CQI feedback is in general supposed to be used for closed-loop transmission It would be better to design pilot pattern to cover low and medium mobility cases We propose that each tile contains two pilots for channel estimation Pilots are located such that average distance between each data and pilots is minimized Pilot density: 16.7 % P Freq. Time

Analysis Results (1/3) PER performance Simulation parameters One MS TX and four BS RX Receiver type: maximal ratio combiner Channel estimator: 2D-MMSE Doppler spread matches 100 km/hr MCS: QPSK ½ Channel model: PB 3 km/hr and VA 120 km/hr SNR (dB) SNR (dB) 2.5 5 7.5 10 12.5 2.5 5 7.5 10 12.5 PER 0.891 0.852 0.840 0.841 2.17e-3 1.17e-3 PER 0.886 0.861 0.860 0.862 2.31e-3 1.71e-3 PB3 VA120

Analysis Results (2/3) UL control example Considered feedback information CQI: 5 bits MIMO mode: 2 bits PMI: 3 bits Number of repetitions: 2 (repetition code is used) MCS: QPSK ½ Num of CQICH+MIMO mode + PMI Num of Tiles Num of CQICH Num of Tiles 1 1 1 2 2 2 2 4 3 3 3 6 4 4 4 8 5 5 5 10 6 6 6 12 7 7 7 14 8 8 8 16 9 9 9 18 10 10 10 20

Analysis Results (3/3) Based on above analysis we have following discussions Considered scenarios : each subframe is allocated to 8 users under 10 MHz bandwidth Case 1: each user feedbacks one CQI per frame Case 2: each user feedbacks 5 CQI values for five subbands per frame and feedback MIMO mode index and PMI every two frames For case 1, UL control overhead is about 2% For case 2, UL control overhead is about 19.29 % Note that multiuser MIMO requires relatively larger UL feedback overhead trading DL spectral efficiency Note that above results are derived without considering any overhead reduction techniques

Conclusion In general case, proposed UL control tile structure can efficiently support UL channel quality feedback For advanced multi-user case, feedback overhead is largely increased, and thus it is suggested to utilize overhead reduction technique to eliminate the incurrence

Text Proposal 11.9.2.1.2 PHY Structure The UL control tile and corresponding pilot pattern are as Figure X. P Freq. Time Figure X. UL control tile.