1 Proposal for IEEE m CQI Feedback Channel Design Document Number: IEEE C80216m-08/937r2 Date Submitted: Source: Hongmei Sun, Changlong Xu, Jong-Kae (JK) Fwu, {hongmei.sun, changlong.xu, jong-kae.fwu Jiacheng Wang, Senjie Zhang, Yang Gao, jiacheng.wang, senjie.zhang, yang.gao, Hujun Yin, Rath Vannithamby, Roshni Srinivasan, hujun.yin, rath.vannithamby, roshni.m.srinivasan, Sassan Ahmadi intel.com Intel Corporation Venue: IEEE Session #57, Kobe, Japan. Re: PHY: SDD Text cleanup; in response to the TGm Call for Contributions and Comments m-08/033 for Session #57 Base Contribution: N/A Purpose: For TGm discussion and adoption of m SDD text. Notice: This document does not represent the agreed views of the IEEE 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 IEEEs name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEEs 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 Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and. Further information is located at and.

2 Outline Requirements on CQI feedback Fast Feedback Channel Design –2-level primary/secondary feedback reporting protocol –Primary fast feedback channel structure –Secondary fast feedback channel structure –Performance and analysis Conclusions SDD Text

3 Primary/Secondary Fast Feedback Channel Protocol UL Primary Fast Feedback channel (PCQICH) –Wideband CQI reports with fixed robust rate periodically –Designed to cover all users –BS makes decision and regulates UEs CQI feedback behavior Resource allocation Feedback frequency –Non-coherent detection UL Secondary fast feedback channel (SCQICH) –To covers users needing narrowband CQI feedback –supports advance features efficiently with link adaptation Adaptation is coarse on users long term statistics Margin is added to guarantee reliability of adaptation –BS decides and schedule SCQICH whether to allocate, when to allocate, the amount of resource and corresponding index, transmission frequency, rate –Coherent detection

4 UL Fast Feedback channel & PHY Structure UL Fast feedback channels are carried in UL Control DRU

5 Fast feedback channel structure -- PCQICH Information Content –4~5 bits payload –Wideband CQI: 4bits Multiplexing: –PFBCH is FDM-ed with UL data and other control channels –Multiple users are FDM/TDM-ed within PCQICH PHY Structure –FMT (Feedback Mini-Tile, N sub x N sym): 2x6 –Each logical FBCH occupies 3 FMTs –Each LRU (18x6) can accommodate 3 FBCH –Coding: semi-orthogonal sequence with BPSK, w. repetition 3

6 UL Fast Feedback Channel Structure – Semi orthogonal sequence of PCQICH Max cross-correlation 4 Support payload bits up to 5 bits Non-coherent detection #sequence #sequence

7 UL Fast Feedback Channel Structure -- SCQICH Information Content –Up to 11/22 bits payload –Narrowband CQI (effective SINR, PMI, RI, indexing) Multiplexing: –SCQICH is FDM-ed with UL data and other control channels –Multiple users are FDM/TDM-ed within SCQICH PHY Structure –FMT size of 2x6 –Each logical SCQICH occupies 3 FMTs (diversity order = 3) –Coding/Modulation : information is encoded to 30bits by puncturing block codes (32, 11, 12), then modulated to 15 QPSK symbols Tile structure of 2x6 11bits payload (rep. 2) 22 bits payload

8 UL Fast Feedback Channel Structure-- SCQICH – Basis sequences for block code (32, 6K11) nS0,nS1,nS2,nS3,nS4,nS5,nS6,nS7,nS8,nS9,nS10,n

9 UL Fast Feedback Channel Structure--SCQICH – Basis sequences for block code (32, 6K11) nS0,nS1,nS2,nS3,nS4,nS5,nS6,nS7,nS8,nS9,nS10,n

10 Simulation Setting Note: identical transmit power per symbol is assumed Channel Bandwidth10MHz Over-sampling Factor28/25 FFT Size1024 Cyclic prefix (CP) ratio1/8 Channel conditionPedB 3km/h, PedA 3km/h The number of antennasTx:1, Rx:2, 4 ModulationBPSK/QPSK Channel estimation2-D MMSE Tile size2x6 Block size6x6 ReceiverPCQICH: non-coherent, MLD SCQICH: coherent MLD

11 Performance results : PCQICH with 4/5bits CQI 4/5bit: -9/-8dB SNR to achieve PER=10% (1x4) guarantees the 95% coverage up to 5km cell size PCQICH: 5bit payload has only 0.5dB loss than that of 4bits payload PCQICH can support very robust CQI transmission

12 Performance results : SCQICH with 11/22 bits CQI

13 Summary 2-level adaptive Primary/Secondary fast feedback channel framework UL Fast feedback channels are carried in UL Control DRU CQI Coding Block size: 6x6 (36 tones total) FMT size: 2x6, with diversity order = 3 for frequency diversity Coding: –PCQICH: semi-orthogonal code, support 4~5 payload bits –SCQICH: Block codes (32, 11, 12), support up to 11/22 payload bits Recommendation –UL Fast feedback channels are classified into 2 types: PCQICH and SCQICH –UL control DRU carries a fast feedback channel consists of 3 distributed tiles –FMT size of 2x6 –Semi-orthogonal sequences are used for PCQICH w/ BPSK –Block codes are used as channel coding scheme for SCQICH w/ QPSK

14 Text proposal to SDD Text Revise the text in red with following modified text in blue (Chapter 11 in [IEEE m- 08/003r4 ]) PHY Structure Replace The structure of the resource blocks, pilots and resource mapping for the UL fast feedback channel are TBD. with UL fast feedback channels are carried in UL control DRU, each feedback channel is 6x6 composed by 3 fast feedback mini-tiles (FMT). Each FMT is 2 contiguous subcarries by 6 OFDM symbols. Primary fast feedback channel uses semi-orthogonal sequences with BPSK modulation, while secondary fast feedback channel uses block codes with QPSK modulation. Adopt SCQICH block sequence shown in page 8,9 Adopt semi-orthogonal sequences shown in page 6 Adopt CQICH design text and figure shown on page 7

15 Backup Slides

16 UL Channel Feedback Design Requirements Overhead: Should reduce the overhead –less than 15% on average. Overhead for distributed is low, but for localized with MIMO would be high –CQI Feedback granularity: Tradeoff between accurate reporting vs. broader reporting; allow optimization for different scenarios; Coverage: CQICH design should be optimized for 1.5km/5km cell sizes with the assumed propagation models; Reliability: In 95% of coverage should be able to decode the relevant CQICH with less than 10% PER; Mobility: CQICH should be able to support optimal DL performance up to 10km/h. CQI feedback mechanism should support advanced PHY/MAC techniques: –frequency selective scheduling (FSS) –MIMO –Fractional frequency reuse (FFR) Error recovery: Error propagation possibility should be avoided or minimized; Complexity: The complexity involved in the CQI feedback scheme should be minimized

17 MIMO Feedback message information Distributed Mode: 4~6bits payload –OL SU-MIMO 5~6bits –Average CQI only: 4 bits 2x2/4x24x4 CQI (bits)44 Rank index (bits)12 Total (bits)56 Localized mode: ~10-21 bits payload –12 sub-bands (assuming RB size of 18x6 and each sub-band includes 4 RBs) –best-M based CQI reporting: M=3 (assuming 10 users) –MIMO modes: CL SU-MIMO, OL MU-MIMO, CL MU-MIMO 2x2, 4x2, 4x4 –Indexing: Format 2 of OL MU-MIMO: others:

18 MIMO Feedback message information (cont.) Narrow band feedback bits per user for different MIMO modes Inf. typeCL SU-MIMOOL MU-MIMOCL MU-MIMO Format 1Format 2 Long periodSubband Index88117 Rank index2~41x3=3n/a Total bits10~1211 2x2=4 Short periodCQI4x3=12 PMI (Transformed codebook) 3x3=9n/a3x3=9 Total bits Note: assuming best-M base

19 PCQICH: 4 bits: 2x6 vs. 3x6 tile size 2x6 is preferred than 3x6

20 SCQICH: 11 bits, 2x6 vs. 3x6 2x6 is preferred compared with 3x6 due to more freq. diversity gain

21 SCQICH: 22 bits, 2x6 vs. 3x6 2x6 has 1dB gain over 3x6