IEEE C802.16m-08/937r2

Transcript IEEE C802.16m-08/937r2

Proposal for IEEE 802.16m CQI Feedback Channel Design

Document Number: IEEE C80216m-08/937r2 Date Submitted: 2008-09-05 Source: Hongmei Sun, Changlong Xu, Jong-Kae (JK) Fwu, Email: {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 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 802.16m-08/033 for Session #57 Base Contribution: N/A Purpose: For TGm discussion and adoption of 802.16m SDD text.

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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 2

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 UE’s 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 3

UL Fast Feedback channel & PHY Structure

(1) Distribute PRU to Freq. Partitions (2) Distribute PRUs to localized and distributed groups

Localized Distributed group Data Control Data

(3) Distribute subcarriers to subchannels (LRUs)

Tile permutation [or hopping] 00 01 02 03 04 05 06 07 08 09 ...

Outer Permutation of PRU to Freq. partitions Localized Data Control Tile permutation [or hopping] Distributed group Data Inter-cell (semi static) Resource groups Single resource Intra-cell (potentially dynamic)

UL Fast feedback channels are carried in UL Control DRU

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 5

UL Fast Feedback Channel Structure

–

Semi orthogonal sequence of PCQICH

# 0 6 7 8 9 1 2 3 4 5 10 11 12 13 14 15 sequence 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 0 1 1 1 0 0 0 1 0 1 0 0 1 0 1 1 1 0 0 0 1 1 1 0 0 1 0 1 1 1 0 0 0 1 0 1 0 0 1 0 1 1 1 0 0 1 0 0 1 0 0 1 0 1 1 1 0 1 0 0 0 1 0 0 1 0 1 1 1 1 1 0 0 0 1 0 0 1 0 1 1 1 1 1 0 0 0 1 0 0 1 0 1 1 1 1 1 0 0 0 1 0 0 1 0 1 0 1 1 1 0 0 0 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 0 0 1 1 1 1 1 1 0 0 1 1 0 1 0 0 0 1 0 0 0 1 0 1 0 0 1 0 0 0 1 0 1 1 0 0 0 0 1 0 1 0 0 0 0 0 1 1 • Max cross-correlation ≤ 4 • Support payload bits up to 5 bits • Non-coherent detection # 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 sequence 0 0 1 0 1 1 0 1 1 1 1 1 0 1 0 0 0 1 1 1 1 0 0 1 0 1 0 0 1 0 1 1 1 1 1 1 0 1 0 0 1 1 0 0 0 0 1 0 0 1 0 1 1 0 0 0 1 0 0 0 0 1 1 0 0 0 0 1 0 1 0 0 0 1 1 1 0 1 0 1 1 1 1 0 0 0 0 1 0 0 0 1 0 1 1 0 0 1 1 0 0 0 1 0 0 0 1 0 0 1 1 1 1 1 0 0 1 1 0 1 0 0 0 0 1 0 0 1 1 0 0 1 0 0 0 0 1 0 1 0 0 1 1 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 1 1 0 0 0 0 0 0 1 1 0 0 0 1 0 0 0 1 6

• • •

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 6 OFDM sysmbols A1 A3 2x6 A1 A4 2x6 P A2 A1 2x6 Tile structure of 2x6 P A3 A2 2x6 11bits payload (rep. 2) A2 A3 A5 A6 2x6 2x6 one coded block 22 bits payload 7

UL Fast Feedback Channel Structure-- SCQICH – Basis sequences for block code (32, 6≤K≤11)

7 8 9 10 1 2

0 3 4 5 6 11 12 13 14 15

S0,n

1 0 1 1 0 0 0 1 0 0 1 1 0 1 1 0 0 1 0 0

S1,n

0 1 0 1 1 0 0 1 1 0 1 1 0 0 1 0

S2,n

0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1

S3,n

0 0 0 0 0 0 0 0 1 1 0 0

S4,n

0 0 0 1 0 1 1 0 0 0 1 0 0 1 1 0

S5,n

0 0 1 0 1 1 0 0 0 1 0 0 1 1 0 1 1 0 0 0

S6,n

0 0 0 0 1 0 1 1 0 0 1 1 1 1 0 0

S7,n

0 0 0 0 0 1 0 0 1 0 0 1 0 1 1 0

S8,n

0 0 0 0 0 0 1 0 0 1 0 0

S9,n

0 0 0 0 0 0 0 1 0 1 1 0 0 0 1 0

S10,n

0 0 0 0 0 0 0 0 1 0 1 1 0 0 0 1 8

UL Fast Feedback Channel Structure--SCQICH – Basis sequences for block code (32, 6≤K≤11)

S0,n

1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 1 23 24 25 26

16 17 18 19 20 21 22 27 28 29 30 31 0 0 0 0

S1,n

0 1 0 1 0 1 0 0 0 0 0 1 1 0 1 0

S2,n

1 0 0 1 1 0 1 1 0 1 0 1 1 1 0 1

S3,n

0 1 0 0 1 1 0 0 1 0 1 1

S4,n

1 1 0 1 0 1 0 1 0 0 0 0 0 0 0 1

S5,n

1 0 1 0 1 0 1 0 0 0 0 0 0 0 0 1 0 1 0 0

S6,n

0 1 1 0 1 0 1 0 0 0 0 1 1 0 1 0

S7,n

1 0 1 1 0 1 0 0 0 0 0 1 0 1 0 1

S8,n

1 1 0 1 1 0 1 0 0 0 0 1

S9,n

0 1 1 0 1 1 0 1 0 1 0 1 0 0 0 1

S10,n

0 0 1 1 0 1 1 0 1 0 1 0 1 0 0 1 9

Simulation Setting

Channel Bandwidth Over-sampling Factor FFT Size Cyclic prefix (CP) ratio Channel condition The number of antennas Modulation Channel estimation Tile size Block size Receiver 10MHz 28/25 1024 1/8 PedB 3km/h, PedA 3km/h Tx:1, Rx:2, 4 BPSK/QPSK 2-D MMSE 2x6 6x6 PCQICH: non-coherent, MLD SCQICH: coherent MLD

Note: identical transmit power per symbol is assumed

Performance results : PCQICH with 4/5bits CQI

PPBCH: 4~5bits: PB3 10 0 10 -1 4bits: 1x2 5bits:1x2 4bits: 1x4 5bits: 1x4 10 -2 10 -3 • • 10 -4 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 SNR (dB) 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 11

Performance results : SCQICH with 11/22 bits CQI

10 0 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 -8 -6 -4 SFBCH: 2x6, 11/22bit (PB3) (non-ideal CE) -2 0 2 SNR (dB) 4 6 8 11bits: 1x2 11bits: 1x4 22bits: 1x2 22bits: 1x4 10 12 12

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 13

Text proposal to SDD Text

Revise the text in red with following modified text in blue (Chapter 11 in [IEEE 802.16m 08/003r4 ])

•

11.9.2.1.2 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 14

Backup Slides

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 16

MIMO Feedback message information

• Distributed Mode: 4~6bits payload – OL SU-MIMO 5~6bits – Average CQI only: 4 bits CQI (bits) Rank index (bits) Total (bits) 2x2/4x2 4 1 5 • 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: log 2 (

3 24 ) • others: log 2 (

3 12 ) 4x4 4 2 6 17

MIMO Feedback message information (cont.)

• Narrow band feedback bits per user for different MIMO modes Inf. type Long period Short period Subband Index Rank index Total bits CQI PMI (Transformed codebook) Total bits CL SU-MIMO 8 2~4 10~12 4x3=12 3x3=9 OL MU-MIMO Format 1 Format 2 8 1x3=3 11 n/a 11 4x3=12 n/a 11 4x3=12 3x3=9 21 12 21 CL MU-MIMO 7 2x2=4 4x3=12 3x3=9 21

Note: assuming best-M base

PCQICH: 4 bits: 2x6 vs. 3x6

10 0 10 -1 PPBCH: 4bits, 2x6 vs. 3x6 (PB3) 2x6: 4bits, 1x2 3x6: 4bits, 1x2 2x6: 4bits: 1x4 3x6: 4bits: 1x4 10 -2 10 -3 10 -4 10 -5 -10 -9 -8 -7 -6 -5 SNR (dB) -4 • tile size 2x6 is preferred than 3x6 -3 -2 -1 0 19

SCQICH: 11 bits, 2x6 vs. 3x6

PB3 - 11 bits - 1x2 10 0 2x6: ideal 2x6: CE 3x6: ideal 3x6: CE 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 -10 -8 -6 -4 -2 0 2 SNR (dB) 4 6 8 10 12 14 15 • 2x6 is preferred compared with 3x6 due to more freq. diversity gain 20

SCQICH: 22 bits, 2x6 vs. 3x6

PB3 - 22 bits - 1x2 10 0 10 -1 10 -2 10 -3 10 -4 10 -5 2x6: Ideal 2x6: CE 3x6: ideal 3x6: CE 10 -6 -10 -8 -6 -4 -2 • 2x6 has 1dB gain over 3x6 0 2 SNR (dB) 4 6 8 10 12 14 15 21