IEEE 802.11-19/1072r0 NGV 20MHz OFDM Numerology Discussions
Dive into the discussions on 20MHz OFDM numerology within IEEE 802.11-19/1072r0, evaluating spectrum masks and transmitter structures. Explore the feasibility of 20MHz waveform designs for DSRC devices meeting class C mask requirements.
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July 2019 doc.: IEEE 802.11-19/1072r0 NGV 20MHz OFDM Numerology Discussions Date: 2019-07-15 Authors: Name Affiliations Address Phone email Rui Cao Marvell 5488 Marvell Ln, Santa Clara, CA 95054 ruicao@marvell.com Sergey Timofeev timoffev@marvell.com hongyuan@marvell.com Hongyuan Zhang Rachel Lim leylim@marvell.com Submission Slide 1 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Introduction 20MHz OFDM numerology was discussed in previous meetings [1]. The OFDM numerology will depend on the corresponding 20MHz spectrum mask definition. We will first discuss the 20MHz spectrum mask for 11bd. Then evaluate the feasibility of two 20MHz OFDM numerology designs using off-the-shelf PA. 11ac 40MHz DC2 11bd 10MHz + 10MHz. Submission Slide 2 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 20MHz Spectrum Mask (Class C) Spectrum Mask (Class C) 0 11p 10MHz Mask 11p 20MHz Mask Potential NGV 20MHz Mask -10 power spectrum density -20 -30 -40 -50 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 frequency (MHz) 11p 20MHz spectrum mask is relatively relaxed than 10MHz mask. 11bd may define a new tighter 20MHz spectrum mask. Similar power leakage as 10MHz mask better adjacent channel operation. Submission Slide 3 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Transmitter Structure Tx Digital Waveform Tx Digital Filter Power Amplifier @5.9GHz LO To the best of our knowledge, DSRC market is looking for devices meeting class C mask. With state-of-art techniques, 11p 10MHz class C mask can be met. Spectrum at band edges can be guaranteed by transmitter digital filter. Spectrum leakage levels at 15MHz and 20MHz is mostly determined by the PA nonlinearity. For 20MHz waveform spectrum, The spectrum leakage to adjacent 10MHz channel (PA non-linearity) will be more severe due to wider signal bandwidth. Need to evaluate feasibility of 20MHz waveform design. Slide 4 Submission Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Spectrum Mask Evaluation Pre-generated digital waveform RF Signal Generator @5.9GHz Spectrum Analyzer Power Amplifier @5.9GHz Evaluate the spectrum of 20MHz signal Pre generate 20MHz digital waveform from simulator Generate the RF waveform through LitePoint VSG. Pass the RF signal to off-the-shelf Skyworks PA (DSRC channels). Analyze the spectrum of the output waveform 20MHz waveform design [1] Waveform 1: 11ac 40MHz DC2 Waveform 2: 11ac 20MHz DC2 + 11ac 20MHz DC2 Submission Slide 5 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Spectrum: 11ac 40MHz DC2 Spectrum of 11ac 40MHz OFDM DC2 waveform 0 -10 -20 power spectrum density -30 -40 -50 11ac 40MHz DC2 Spectrum (20dBm PA output) 11p 20MHz Mask (class C) Potential NGV 20MHz Mask (class C) -60 -70 -50 -40 -30 -20 -10 0 10 20 30 40 50 frequency (MHz) Good margin compared to 11p 20MHz mask. Difficult to meet the tight mask @+/-20MHz frequency. Need >6dB more suppression from PA to temperature sweep and max-hold measurment. Submission Slide 6 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Spectrum: 10MHz + 10MHz Spectrum of 10in20MHz waveform 0 -10 -20 power spectrum density -30 -40 -50 -60 10in20MHz spectrum (20dBm PA output) 11p 20MHz Mask (class C) Potential NGV 20MHz Mask (class C) -70 -50 -40 -30 -20 -10 0 10 20 30 40 50 frequency (MHz) With off-the-shelf PA, the tight spectrum mask can be met with sufficient margin using 10MHz + 10MHz design. Submission Slide 7 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Summary Discussed new 20MHz spectrum mask definition. Measured the spectrum of two different 20MHz signal generation methods using off-the-shelf PA. Option 1: 11p 20MHz spectrum mask Both (11ac 40MHz DC2) and (11bd 10MHz + 11bd 10MHz) can meet. Option 2: a new tight 20MHz spectrum mask with same leakage level as 10MHz spectrum mask. 11ac 40MHz DC2 is very challenging with exiting PA, most at 20MHz. Need to choose 10+10MHz OFDM numerology with two-PA design. May design single-PA system when better PA is available in the future. Option 3: a compromised 20MHz spectrum mask with similar leakage level as 10MHz spectrum mask, but relaxed at +/-20MHz. For example, -45dBr. Submission Slide 8 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Reference [1] Rui Cao and etc., PHY Numerology Discussions , IEEE 802.11-19/0686. Submission Slide 9 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Straw Poll 1 Do you agree that 11bd shall define 20MHz spectrum mask as follows? Option A: 11p 20MHz spectrum mask Option B: A new tight spectrum mask with the same leakage level as 10MHz spectrum mask? Option C: A new tight spectrum mask with similar leakage level as 10MHz spectrum mask, but with xdB relaxed at +/-20MHz from center frequency? Option A: Option B: Option C: Abstain: Submission Slide 10 Rui Cao and etc., Marvell
July 2019 doc.: IEEE 802.11-19/1072r0 Straw Poll 2 Do you agree that 11bd 20MHz PPDU Data symbol shall use the following OFDM design? 11ac 40MHz downclock by 2 11bd 10MHz + 11bd 10MHz. Option A: Option B: Abstain: Submission Slide 11 Rui Cao and etc., Marvell
