March 2012 doc IEEE 802 11 12349 r

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March 2012 doc. : IEEE 802. 11 -12/349 r 2 DFT spreading OFDM options

March 2012 doc. : IEEE 802. 11 -12/349 r 2 DFT spreading OFDM options for 11 ah PHY enhancement Authors: Masahiro Umehira et. al Submission Date: 2012 -3 -15 Slide 1

November 2011 doc. : IEEE 802. 11 -12/349 r 2 Abstract • This presentation

November 2011 doc. : IEEE 802. 11 -12/349 r 2 Abstract • This presentation proposes DFT spreading OFDM options for 11 ah PHY enhancement. Masahiro Umehira et. al Submission Slide 2

November 2011 doc. : IEEE 802. 11 -12/349 r 2 Overview • TGah decided

November 2011 doc. : IEEE 802. 11 -12/349 r 2 Overview • TGah decided to support 2/4/8/16 MHz signals based on the down clocked versions of 11 ac 20/40/80/160 MHz, and an 1 MHz signal based on 32 FFT. – Both 2 MHz and 1 MHz receptions are mandatory in TGah PHY. • DFT spreading OFDM (DFTS-OFDM) is adopted for the uplink in IMT-2000 LTE, and the concept of DFTSOFDM was presented in IEEE 802. 11 -11/0753 r 0. • We propose DFTS-OFDM options for 11 ah PHY enhancement for 1 MHz and 2 MHz signals, especially for the purpose of sensor applications in this presentation. – – Advantage of DFT-spreading OFDM Proposal of DFT spreading OFDM option. Masahiro Umehira et. al Submission Slide 3

doc. : IEEE 802. 11 -12/349 r 2 Why DFTS-OFDM ? • Battery driven

doc. : IEEE 802. 11 -12/349 r 2 Why DFTS-OFDM ? • Battery driven wireless terminals are used for sensor network applications • Basic Requirements for the use cases of 1 a/1 f and 2 d/2 e/2 f – – Relatively low transmission speed Long battery life time Reduced power consumption at wireless sensor terminals Higher efficiency at HPA, i. e. low output back-off operation • Computer simulation results on PAPR, Power spectrum after HPA and BER are shown in the following slides. – 56 points DFT spreading is assumed. Masahiro Umehira et. al Submission Slide 4

doc. : IEEE 802. 11 -12/349 r 2 Comparison of PAPR Cumulative Probability DFTS-OFDM

doc. : IEEE 802. 11 -12/349 r 2 Comparison of PAPR Cumulative Probability DFTS-OFDM achieved lower PAPR than OFDM. 10 0 10 -1 10 -2 10 -3 10 -4 10 -5 10 -6 Masahiro Umehira et. al Submission 56 subcarriers 56 point DFT spreading 64 point IFFT QPSK 2. 5 d. B @0. 1% : OFDM : DFTS-OFDM 0 2 4 6 8 Instantaneous Power [d. B] Slide 5 10

doc. : IEEE 802. 11 -12/349 r 2 Comparison of output spectrum after HPA

doc. : IEEE 802. 11 -12/349 r 2 Comparison of output spectrum after HPA • DFTS-OFDM achieved less ACL (adjacent channel power leakage) when output backoff is small. • DFTS-OFDM is more suitable for low output backoff operation. Note: 1/To=Subcarrier spacing 0 : OFDM : DFTS-OFDM -5 PSD [d. B] -10 -15 OBO=0 d. B -20 -25 -30 -35 -40 0 Masahiro Umehira et. al Submission OBO=3 d. B OBO=6 d. B Rapp model (smooth factor=2) 32 64 96 Normalized Frequency [1/To] Slide 6 128

doc. : IEEE 802. 11 -12/349 r 2 BER performance • DFTS-OFDM achieved better

doc. : IEEE 802. 11 -12/349 r 2 BER performance • DFTS-OFDM achieved better BER performance, when OBO=0 d. B-3 d. B. 100 QPSK Uncoded AWGN 10 -1 BER 10 -2 10 -3 : QPSK Theory : OFDM 0 d. B : OFDM 3 d. B : OFDM 6 d. B : DFTS-OFDM 0 d. B : DFTS-OFDM 3 d. B : DFTS-OFDM 6 d. B 10 -4 10 -5 10 -6 0 Masahiro Umehira et. al Submission 5 Eb/N 0 [d. B] 10 Slide 7 15

doc. : IEEE 802. 11 -12/349 r 2 Transmission flow for DFTS-OFDM options (1)

doc. : IEEE 802. 11 -12/349 r 2 Transmission flow for DFTS-OFDM options (1) • DFTS-OMDF options will be useful for 1 MH/2 MHz BPSK/QPSK signals. • It is desirable not to change the basic signal design and preamble of OFDM signals. – 1 MHz (32 FFT) • 24 Data tones, 2 Pilot tones, 5 Guard tones, and 1 DC tone – 2 MHz(64 FFT) • 52 Data tones, 4 Pilot tones, 7 Guard tones, and 1 DC tone AH-STF AH-LTF AH-SIG AHLTF 1 DFTSOFDM 2 … DFTSOFDM n DFT Spreading is applied in the data field only. Masahiro Umehira et. al Submission Slide 8

January 2012 doc. : IEEE 802. 11 -12/349 r 2 Transmission flow for DFTS-OFDM

January 2012 doc. : IEEE 802. 11 -12/349 r 2 Transmission flow for DFTS-OFDM options (2) : Additional functions for DFTS-OFDM enhancement Scrambler FEC Interleaver BPSK/QPSK mapper DFT IDFT GI & Window Analog & RF (a) Transmission side for DFTS-OFDM enhancement De. Scrambler FEC decoder Deinterleaver BPSK/QPSK De-mapper IDFT Frequency Domain Equalization DFT GI & Window Analog & RF (b) Reception side for DFTS-OFDM enhancement • DFT on the transmission side – 26 or 27 points DFT for 1 MHz, 56 or 57 points DFT for 2 MHz • IDFT and FDE on the reception side – 26 or 27 points IDFT for 1 MHz, 56 or 57 points IDFT for 2 MHz – FDE is performed using CSI Masahiro Umehira et. al Submission Slide 9 Hongyuan Zhang, et. Al.

November 2011 doc. : IEEE 802. 11 -12/349 r 2 Discussions • 57 DFT/IDFT

November 2011 doc. : IEEE 802. 11 -12/349 r 2 Discussions • 57 DFT/IDFT is the simplest approach for DFTS-OFDM, however FFT algorithm can not be applied for DFT/IDFT implementation since 57 is not power of two. – It needs large amount of signal processing for DFT/IDFT. • 56 DFT/IDFT is another simple approach for DFTS-OFDM. – 56 DFT/IDFT needs less amount of signal processing than 57 DFT/IDFT. – DC tone is replaced with one data tone. • Though 57/56 DFT/IDFT needs large amount of signal processing, it is worth employing DFTS-OFDM for 1 MHz/2 MHz signals for sensor network applications where low PAPR is strongly desired. – Direct DFT/IDFT will be possible because of its low symbol rate. – Other DFTS-OFDM based approaches can be employed based on the trade -off between PAPR and signal processing. Masahiro Umehira et. al Submission Hongyuan Zhang, et. Al. Slide 10

November 2011 doc. : IEEE 802. 11 -12/349 r 2 Straw Poll • Do

November 2011 doc. : IEEE 802. 11 -12/349 r 2 Straw Poll • Do you support DFTS-OFDM based options for 11 ah PHY enhancement for its advantage of low PAPR and better BER performance in non-linear HPA operation ? – Applied only for 1 MHz/2 MHz signals with BPSK/QPSK mode. – Needs further considerations on other approaches based on tradeoff between PAPR and signal processing. Masahiro Umehira et. al Submission Slide 11 Hongyuan Zhang, et. Al.

November 2011 doc. : IEEE 802. 11 -12/349 r 2 References [1] 011 -11

November 2011 doc. : IEEE 802. 11 -12/349 r 2 References [1] 011 -11 -0753 -00 -00 ah-dft-spread-ofdm-optimized-for 802 -11 ah [2] 11 -11 -1482 -00 -00 ah-preamble-format-for-1 -MHz [3] 11 -11 -1483 -00 -00 ah-11 ah-preamble-for-2 MHz-andbeyond [4] 11 -11 -1484 -06 -00 ah-11 ah-phy-transmission-flow Masahiro Umehira et. al Submission Slide 12 Hongyuan Zhang, et. Al.