doc.: ieee 802.11-12/1104r2 submission 11ah interframe spacing values date: 2012-09-17 authors:...

doc.: IEEE 802.11-12/1104r2

Submission

11ah Interframe Spacing Values

Date: 2012-09-17

Authors:

September 2012

Tevfik Yucek, Qualcomm Inc.Slide 1

Name Affiliations Address Phone email Tevfik Yucek Qualcomm Inc +1 408 5074286 tyucek@qca.qualcomm.com

Harya Wicaksana Panasonic R&D center Singapore

Blk1022 Tai Seng Ave #06-3530 Singapore

+65-65505347 harya.wicaksana@sg.panasonic.com

Rojan Chitrakar Panasonic R&D center Singapore Rojan.Chitrakar@sg.panaso

nic.com

Ken Mori Panasonic Corp Mori.ken1@jp.panasonic.com

Hongyuan Zhang Marvell Hongyuan@marvell.com

Sudhir Srinivasa Marvell sudhirs@marvell.com

Yong Liu Marvell yongliu@marvell.com

Eldad Perahia Intel Corp. eldad.perahia@intel.com

Shahrnaz Azizi Intel Corp. shahrnaz.azizi@intel.com

Tom Tetzlaff Intel Corp. thomas.a.tetzlaff@intel.com

Thomas Kenney Intel Corp. thomas.j.kenney@intel.com

Yongho Seok LG Electronics LG R&D Complex Anyang-Shi, Kyungki-Do, Korea

+82-31-450-1947 yongho.seok@lge.com

Jinsoo Choi LG Electronics

Jeongki Kim LG Electronics

doc.: IEEE 802.11-12/1104r2

Submission

Authors:

September 2012

Tevfik Yucek, Qualcomm Inc.Slide 2

Name Affiliations Address Phone email Sameer Vermani Qualcomm

Eugene Baik Qualcomm

Lin Yang Qualcomm

Hemanth Sampath Qualcomm

Richard Van Nee Qualcomm

Allert Van Zelst Qualcomm

VK Jones Qualcomm

Sun, Bo ZTE sun.bo1@zte.com.cn

Lv, Kaiying ZTE lv.kaiying@zte.com.cn

Huai-Rong Shao Samsung hr.shao@samsung.com

Chiu Ngo Samsung chiu.ngo@samsung.com

Minho Cheong ETRI 138 Gajeongno, Yuseong-gu, Dajeon, Korea

+82 42 860 5635 minho@etri.re.kr

Jae Seung Lee ETRI jasonlee@etri.re.kr

Hyoungjin Kwon ETRI kwonjin@etri.re.kr

Heejung Yu ETRI heejung@etri.re.kr

Jaewoo Park ETRI parkjw@etri.re.kr

Sok-kyu Lee ETRI Sk-lee@etri.re.kr

Sayantan Choudhury Nokia

Taejoon Kim Nokia

Klaus Doppler Nokia

doc.: IEEE 802.11-12/1104r2

Submission

Authors:

September 2012

Tevfik Yucek, Qualcomm Inc.Slide 3

Name Affiliations Address Phone email Zander Lei I2R 1 Fusionopolis Way, #21-01

Connexis Tower, Singapore 138632

+65-6408 2000 leizd@i2r.a-star.edu.sg

Li Chia Choo I2R choolc@i2r.a-star.edu.sg

Zhou Yuan I2R yzhou@i2r.a-star.edu.sg

Sumei Sun I2R sunsm@i2r.a-star.edu.sg

Ser Wah Oh I2R swoh@i2r.a-star.edu.sg

George Calcev Huawei Rolling Meadows, IL USA

George.Calcev@huawei.com

Osama Aboul Magd Huawei Osama.AboulMagd@huawei.com

Young Hoon Kwon Huawei Younghoon.Kwon@huawei.com

Betty Zhao Huawei Betty.Zhao@huawei.com

David Yangxun Huawei David.Yangxun@huawei.com

Bin Zhen Huawei ZhenBin@huawei.com

ChaoChun Wang MediaTek chaochun.wang@mediatek.com

James Wang MediaTek james.wang@mediatek.com

Jianhan Liu MediaTek jianhan.liu@mediatek.com

Vish Ponnampalam MediaTek vish.ponnampalam@mediatek.com

James Yee MediaTek james.yee@mediatek.com

Thomas Pare MediaTek thomas.pare@mediatek.com

Kiran Uln MediaTek kiran.uln@mediatek.com

Ron Porat Broadcom

Nihar Jindal Broadcom

Vinko Erceg Broadcom

doc.: IEEE 802.11-12/1104r2

Submission

Introduction

• SIFS time and slot duration are important keeping the overhead small [1]

• We investigate the components that makes up SIFS and Slot durations and propose values that are suitable for 802.11ah

September 2012

Tevfik Yucek, Qualcomm Inc.Slide 4

doc.: IEEE 802.11-12/1104r2

Submission

Definitions

Slide 5 Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

Definitions

• SIFSTime = aRxRFDelay + aRxPLCPDelay + aMACProcessingDelay + aRxTxTurnaroundTime.

• SlotTime = aCCATime + aRxTxTurnaroundTime + aAirPropagationTime+ aMACProcessingDelay

Slide 6 Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

Values• aAirPropagationTime

– Twice the propagation time (in microseconds) for a signal to cross the maximum distance between the most distant allowable STAs that are slot synchronized.

– Assuming 300 and 900 meters range for 11n/ac and 11ah respectively, corresponding values are 2us and 6us.

• aRxPLCPDelay, aMACProcessingDelay, aTxPLCPDelay– These are digital processing delays and depend on the digital clock rate. Assuming 11n/ac

baseband is downclocked by 10, values need to be increased by 10.– MAC processing time / TxPLCPDelay for Slot is set to zero since the MAC calculation

can be done before transmission.

• aTxRampOnTime and aRxTxSwitchTime are assumed to be the same for 11n/ac and 11ah

• aTxRFDelay and aRxRFDelay– Assuming the same filter order, delay increases 10x due to 10x bandwidth scaling (2MHz

vs. 20MHz).– We assume 1MHz will use the same filter with 2MHz mode. If narrower filters are used,

we assume smaller digital delay of 1MHz will compensate the longer filter delay.Slide 7 Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

CCA Time: Theoretical considerations

• Due to 20x BW reduction, CCA time needs to be increased 20x compared to 11n/ac– For same SNR, 1MHz STF requires 2x the integration time of

2MHz (less number of samples per symbol).

• Furthermore, to improve the detection to an SNR supported by Rep2 packets, CCA time needs to be increased by 2– Required SNR is 3dB lower for MCS0 rep2

• However, STFs are power boosted by 3dB for rep2• This results in theoretical value of 4*20*2/2 = 80us CCA

duration

Slide 8 Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

CCA Time: Practical requirements

• 10% PER point for MCS0-Rep2 requires >8dB SNR at Urban Macro channel model

• Figures in the next page shows the ROC curves for detecting valid PPDU transmissions in– 11dB STF-SNR in SCM Urban Macro channel model– 0dB STF-SNR in AWGN channel– 3dB STF-SNR in AWGN channel

• Simple correlation algorithm based on STFs is used• It is possible to meet the 90% detection requirement using

40us CCA duration for both bases (fading and AWGN).– Values less then 40us can be used. However, 40us gives some room in

implementation error. For example, a single detection threshold is used across different channel conditions.

Slide 9 Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

CCA Results – Urban Macro

Slide 10

0 0.02 0.04 0.06 0.08 0.10.95

0.955

0.96

0.965

0.97

0.975

0.98

0.985

0.99

0.995

1

FA probability

Po

sitiv

e d

ete

ct p

rob

ab

ility

BW=1MHz, SNR=11dB, Urban Macro

20us22us24us26us28us30us32us34us36us38us40us

Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

CCA Results – AWGN

Slide 11

0 0.005 0.01 0.015 0.020.9

0.91

0.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

1

FA probability

Po

sitiv

e d

ete

ct p

rob

ab

ility

BW=1MHz, SNR=0dB, AWGN

20us22us24us26us28us30us32us34us36us38us40us

Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

CCA Results – AWGN

Slide 12

0 0.005 0.01 0.015 0.020.9

0.91

0.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

1

FA probability

Po

sitiv

e d

ete

ct p

rob

ab

ility

BW=1MHz, SNR=3dB, AWGN

20us22us24us26us28us30us32us34us36us38us40us

0 0.5 1 1.5 2

x 10-3

0.95

0.955

0.96

0.965

0.97

0.975

0.98

0.985

0.99

0.995

1

FA probability

Po

sitiv

e d

ete

ct p

rob

ab

ility

BW=1MHz, SNR=3dB, AWGN

Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

Slot Time

Slide 13

11ac 11ah

CCA Time 4 40

Air Propagation Time 2 6

aMACProcessingDelay 1 0

aRxTxTurnaroundTime (aTxPLCPDelay+aRxTxSwitchTime+aTxRampOnTime+aTxRFDelay

2 (1, 0.25, 0.25, 0.5)

5.5 (0+0.25+0.25+5)

SlotTime 9 51.5 52

Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

SIFS

Slide 14

11n/ac 11ah

aRxRFDelay .5 5

aRxPLCPDelay 12.5 125

aMACProcessingDelay 1 10

aRxTxTurnaroundTime (aTxPLCPDelay+aRxTxSwitchTime+aTxRampOnTime+aTxRFDelay

2 (1, 0.25, 0.25, 0.5)

15.5 (10+0.25+0.25+5)

SIFS 16 155.5 156

Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

SIFS: Multiple of symbol duration

• We propose to use 160us SIFS time which is a multiple of 40us symbol duration (normal GI)

• This is less efficient but it would allow to the NAV to be expressed in terms of symbol duration, allowing for compressed representation of Duration/NAV field in MAC/PHY fields.

• If any transmission in a TXOP uses short GI, the duration defined by 40us unit might be slightly longer than the actual transmission sequence, but the difference is less than 1 symbol; which should not cause big impact

• Note that 11ac short GI has similar issue

September 2012

Tevfik Yucek, Qualcomm Inc.Slide 15

doc.: IEEE 802.11-12/1104r2

Submission

Pre-motion

• Do you support the following proposed interframe spacing related values– SIFS=160us, – Slot time=52us– aCCATime = 40us– aAirPropagationTime = 6us

– Yes:– No:– ABS:

Slide 16 Tevfik Yucek, Qualcomm Inc.

doc.: IEEE 802.11-12/1104r2

Submission

References

• [1] IEEE 11-12-0362, On the 802.11ah Performance

Slide 17 Tevfik Yucek, Qualcomm Inc.