Sounding Sequences Comparison for IEEE 802.16m

IEEE 802.16 Presentation Submission Template (Rev. 9)Document Number: IEEE C80216m-09/2232Date Submitted: 2009-11-06Source:

Ying Li, Yen-Wen Huang E-mail: eeyli@saturn.yzu.edu.twYuan Ze University

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Venue: IEEE Session #64, Atlanta, GeorgiaRe: IEEE 802.16-09/0057, “IEEE 802.16 Working Group Letter Ballot Recirc #30a, on P802.16m/D2” Base Contribution: N/APurpose: To be discussed in TGm for the IEEE P802.16m/D2 Draft.Notice:

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Introduction

• Existing sounding sequence adopted for 802.16m– Sequence I (C80216m_09/0771): 802.16e sequence

based on BPSK Golay Sequence

– Intel proposed, compared with Samsung proposed poly-phase sequences in C80216m_09/1121

• Proposed sounding sequence: 802.16e compatible sequences based on QPSK Golay sequences

• Comparison: PAPR, cross correlation, complexity

2 3 4 5 6 7 8 9 10 11 12 130

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PAPR [dB]

CD

F

seq.1, P = 4seq.1, P = 8seq.1, P = 16seq.1, P = 32seq.2, P = 4seq.2, P = 9seq.2, P = 18seq.2, P = 32

PAPR Analysis: CDM (Cyclic Shift Separability)

• 1024 FFT Nused=865 Loading size 864 tones (12 subbands)

Seq. 1: Existing Seq (Intel)Seq. 2: Samsung (not adopted)PAPR 4~9dB（ from C80216m_09/1121)

YZU Proposed Sounding Seq.PAPR <= 3.0103 dBPAPR variance small

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PAPR [dB]

CD

F

seq.1, D = 4seq.1, D = 8seq.1, D = 16seq.1, D = 32seq.2, D = 4seq.2, D = 9seq.2, D = 18seq.2, D = 32

PAPR Analysis: FDM (Decimation Separability)

• 1024 FFT Nused=865 Loading size 864 tones (12 subbands)

Seq. 1: Existing Seq (Intel)Seq. 2: Samsung (not adopted)PAPR 2~9dB（ from C80216m_09/1121)

YZU Proposed Sounding Seq.PAPR <= 3.0103 dBPAPR variance small

Cross Correlation Analysis

• Table and Figures are from Samsung’s report (C80216m_09/0849) Seq. 1 (802.16e, Intel) Seq. 2(Samsung)

16e Proposed Gain

PAPR 5dB ~ 7dB 3dB ~ 7dB 0dB ~ 4dB*

Probability of zero correlation

40% 85% 45%*

Sounding SNR 5dB ~ 6dB 6dB~10dB 1dB ~ 4dB*

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Correlation

pdf

(%)

Cross Correlation of 16e Sequence, P = 18

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Correlation

pdf

(%)

Cross Correlation of Proposed Sequence, P = 18

Cross Correlation Analysis

• Probability of zero cross correlation high (greater than 90% in FDM)

• Maximum cross correlation <0.5 • (Maximum cross correlation=1 for Intel and Samsung’s

sequences)

Proposed Sounding Sequences

• Performance overview– Max PAPR higher for larger D (PAPR=6.72dB, D=16,

1024-FFT ), but not for larger P

– Max Cross Correlation for larger D, P

– Total No. of Seq. U*D or U*P, for large FFT U can increase

Complexity Analysis

• Existing sounding sequence adopted for 802.16m– Alphabet size

• 2 for FDM• lcm(2, P) for CDM

– BPSK Golay Sequence of length 1024 stored in lookup table (table corruption error in 2004 standard, corrected in 2006, updated in standard in 2009)

• Proposed sounding sequence– Alphabet size (moderate Increase in alphabet size)

• lcm(2, D) for FDM• lcm (4, P) for CDM

– QPSK Golay sequence from recursive construction (no need for lengthy lookup tables, prevent errors)

Conclusion

• Existing Seq. have >3dB PAPR and large PAPR variance due to length mismatch/ puncturing

• Proposed Seq. based on QPSK Golay Seq. are compatible with 802.16e, have 3dB PAPR (higher power efficiency), Lower Cross Correlation (less interference), with moderate complexity increase

• Recommendation: Adopt proposed Seq. for 802.16m uplink sounding