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160 MHz Transmissions

160 MHz Transmissions. Authors:. Date: 2010-07-12. Background. TGac has adopted 160 MHz PHY transmission [1] R3.1.1.A: The draft specification shall include support for 160 MHz PHY transmission. R3.1.1.B: Tone allocation for 160 MHz operation shall consist of two 80 MHz tone allocations.

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160 MHz Transmissions

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  1. 160 MHz Transmissions Authors: Date: 2010-07-12 Youhan Kim, et al.

  2. Background • TGac has adopted 160 MHz PHY transmission [1] • R3.1.1.A: The draft specification shall include support for 160 MHz PHY transmission. • R3.1.1.B: Tone allocation for 160 MHz operation shall consist of two 80 MHz tone allocations. • R3.1.1.C: The draft specification shall include support for non-contiguous 160 MHz PHY transmission whose frequency spectrum consists two segments, each transmitted using any two 11ac 80 MHz channels, possibly non-adjacent in frequency. Contiguous and non-contiguous 160 MHz devices shall be capable of transmitting and receiving frames between each other when the two segments of the non-contiguous 160 MHz device are placed in frequency to match the tone allocation of the contiguous 160 MHz device. • Additional details for 160 MHz PHY transmissions are provided Youhan Kim, et al.

  3. Reference Oscillator • 11n • Transmit chain center frequency and symbol clock frequency for all transmit antennas shall be derived from the same reference oscillator • Propose for 11ac • Transmit chain center frequency and symbol clock frequency for all transmit antennas and frequency segments shall be derived from the same reference oscillator • Makes the center frequency and symbol clock frequency between frequency segments of non-contiguous transmitters be locked in frequency • Not practical for the two frequency segments in a single system to use separate reference oscillators anyhow Youhan Kim, et al.

  4. Phase of LO BetweenLower and Upper 80 MHz of 160 MHz (1) • Tone allocation of contiguous 160 MHz consists of two 80 MHz tone allocations • Identical to tone allocation of non-contiguous 160 MHz with two freq. segments placed next to each other • What else is needed for interoperability between contiguous and non-contiguous 160 MHz devices? • Suppose • TX: Non-contiguous 160 MHz device • RX: Contiguous 160 MHz device Non-Contiguous TX Contiguous RX D A C A D C 160 MHz D A C Segment 0 Segment 1 PLL PLL The non-contiguous TX placed its two frequency segments next to each other to communicate with contiguous RX PLL Ref. Osc. Ref. Osc. Youhan Kim, et al.

  5. Phase of LO BetweenLower and Upper 80 MHz of 160 MHz (2) • Unreasonable to assume that the two frequency segments from a non-contiguous TX have identical phase/phase noise (two separate PLLs) • To ensure that contiguous devices can properly receive signals transmitted from non-contiguous devices • Phase of LO shall not be assumed to be correlated between the lower and upper 80 MHz frequency portions of 160 MHz PPDUs being transmitted • Contiguous RX to perform phase tracking per lower and upper 80 MHz portions separately • 8 pilot tones per 80 MHz portions sufficient for separate phase tracking • Contiguous RX to not perform channel smoothing across the boundary of lower and upper 80 MHz portions • Already at least 3.75 MHz gap between the lower and upper 80 MHz anyhow 80 MHz 80 MHz 11 DC tones (3.75 MHz gap) Youhan Kim, et al.

  6. 160 MHz Reusing 80 MHz • Tone allocation for 160 MHz transmissions consists of two 80 MHz tone allocations repeated twice in frequency [1] • Propose to repeat 80 MHz preamble and pilot mapping twice in frequency for 160 MHz • 160 MHz tone allocation naturally paves way to reusing of 80 MHz HW to support 160 MHz transmissions 80 MHz 80 MHz 80 MHz tone allocation 80 MHz tone allocation Youhan Kim, et al.

  7. Preamble for 160 MHz Transmissions (1) • Extend 80 MHz preamble to 160 MHz preamble by simple repetition in frequency • Phase rotation per 20 MHz subchannel (from L-STF to VHT-SIG B) • 80 MHz : [1, -1, -1, -1] (see ref. [2]) • 160 MHz : [1, -1, -1, -1, 1, -1, -1, -1] • L-STF sequence • Repeat the 11n 20 MHz L-STF pattern given in Equation (20-8) in each 20 MHz subchannel • L-LTF sequence • Repeat the 11n 20 MHz L-LTF pattern given in Equation (20-11) in each 20 MHz subchannel Youhan Kim, et al.

  8. Preamble for 160 MHz Transmissions (2) • VHT-STF sequence • Repeat the 80 MHz VHT-STF sequence [3] twice in frequency where VHTSTF-122,122 is the VHT-STF sequence for 80 MHz [3] Youhan Kim, et al.

  9. Preamble for 160 MHz Transmissions (3) • VHT-LTF sequence • Repeat the 80 MHz VHT-LTF sequence [2] twice in frequency where VHTLTF-122,122 is the VHT-LTF sequence for 80 MHz [2] Youhan Kim, et al.

  10. Phase Rotation for Data Symbols • Apply the same phase rotation per 20 MHz subchannel used for preamble to the data symbols • [1, -1, -1, -1, 1, -1, -1, -1] Youhan Kim, et al.

  11. Pilot Sequence for Data Symbols (1) • Pilot tones in VHT-LTF has been proposed [4] • Same pilot sequence values for all space-time streams • Allows phase tracking during VHT-LTF for enhanced channel estimation quality • Needed to support higher order MIMO, 256-QAM, DL MU-MIMO • Pilot sequence for 20/40/80 MHz proposed in [5] • Same pilot sequence values for all space-time streams • Allows phase tracking w/o MIMO channel estimation for pilot tones • Repeat 80 MHz pilot sequence and mapping twice in frequency for 160 MHz transmissions Youhan Kim, et al.

  12. Pilot Sequence for Data Symbols (2) • The pilot tone mapping in 160 MHz where n is the 80 MHz pilot pattern [5], and n is the VHT-DATA symbol index • Including the pseudo random scrambling sequence, the pilot value for the kth tone, with k = {±25, ±53, ±89, ±117, ±139, ±167, ±203}, is pn+zPnk, where z = 4 for VHT, and where pn is defined in Section 17.3.5.9 of IEEE802.11 • This does not include the rotation per 20 MHz subchannel yet Youhan Kim, et al.

  13. Summary • Transmit chain center frequency and symbol clock frequency for all transmit antennas and frequency segments shall be derived from the same reference oscillator • All transmit chains and frequency segments are frequency locked • Phase of LO shall not be assumed to be correlated between the lower and upper 80 MHz frequency portions of 160 MHz PPDUs being transmitted • Ensure contiguous 160 MHz RX can receive 160 MHz PPDUs from non-contiguous 160 MHz TX • 160 MHz preamble constructed by repeating the 80 MHz preamble twice in frequency • 80 MHz L-STF, L-LTF, L-SIG, VHT-STF, VHT-LTF repeated twice • 80 MHz phase rotation per 20 MHz subband repeated twice • Extend the phase rotation per 20 MHz subband of the 160 MHz preamble to the 160 MHz data portion • 160 MHz pilot mapping obtained by repeating the 80 MHz pilot mapping twice in frequency Youhan Kim, et al.

  14. Straw Poll #1 • Do you support adding the following item into the specification framework document, 11-09/0992? • R3.X: Carrier (LO) and symbol clock frequencies for all transmit chains and frequency segments shall be derived from the same reference oscillator. Youhan Kim, et al.

  15. Straw Poll #2 • Do you support adding the following item into the specification framework document, 11-09/0992? • R3.X: Phase of carrier frequency shall not be required to be correlated between the lower and upper 80 MHz frequency portions of the transmitted signal for 160 MHz PPDUs. Youhan Kim, et al.

  16. Straw Poll #3 • Do you support adding the following items into the specification framework document, 11-09/0992?(Refer to slides 6-9) • 3.2.3 VHT preamble • The L-STF, L-LTF, L-SIG, VHT-STF and VHT-LTF portions of preamble for 160 MHz VHT transmissions shall be constructed by repeating the 80 MHz counterparts twice in frequency, once in the lower 80 MHz subchannel and one more time in the upper 80 MHz subchannel of the 160 MHz bandwidth. • 3.2.3.1.2 L-STF definition • The L-STF pattern for 160 MHz VHT transmissions shall repeat the 80 MHz L-STF pattern twice in frequency. This corresponds to repeating the 11n 20 MHz L-STF pattern in Equation (20-8) in each of the 20 MHz subchannel, then applying the following phase rotation per 20 MHz subchannel starting from the lowest 20 MHz subchannel in frequency: [c80 c80], where c80 is the phase rotation per 20 MHz subchannel for 80 MHz transmissions. Youhan Kim, et al.

  17. Straw Poll #3 (Cont’d) • 3.2.3.1.3 L-LTF definition • The L-LTF pattern for 160 MHz VHT transmissions shall repeat the 80 MHz L-LTF pattern twice in frequency. This corresponds to repeating the 11n 20 MHz L-LTF pattern in Equation (20-11) in each of the 20 MHz subchannel, then applying the following phase rotation per 20 MHz subchannel starting from the lowest 20 MHz subchannel in frequency: [c80 c80], where c80 is the phase rotation per 20 MHz subchannel for 80 MHz transmissions. • 3.2.3.1.4 L-SIG definition • L-SIG for 160 MHz VHT transmissions shall be constructed by repeating the L-SIG for 80 MHz VHT transmissions twice in frequency, once in the lower 80 MHz subchannel and one more time in the upper 80 MHz subchannel of the 160 MHz bandwidth. The following phase rotation per 20 MHz subchannel shall be applied starting from the lowest 20 MHz subchannel in frequency: [c80 c80], where c80 is the phase rotation per 20 MHz subchannel for 80 MHz transmissions. Youhan Kim, et al.

  18. Straw Poll #3 (Cont’d) • 3.2.3.2.3 VHT-STF definition • VHT-STF sequence for 160 MHz VHT transmissions shall be constructed by repeating the VHT-STF sequence for 80 MHz VHT transmissions twice in frequency as follows where VHTSTF-122,122 is the VHT-STF sequence for 80 MHz VHT transmissions. The following phase rotation per 20 MHz subchannel shall be applied starting from the lowest 20 MHz subchannel in frequency: [c80 c80], where c80 is the phase rotation per 20 MHz subchannel for 80 MHz transmissions. • 3.2.3.2.4 VHT-LTF definition • VHT-LTF sequence for 160 MHz VHT transmissions shall be constructed by repeating the VHT-LTF sequence for 80 MHz VHT transmissions twice in frequency as follows where VHTLTF-122,122 is the VHT-LTF sequence for 80 MHz VHT transmissions. The following phase rotation per 20 MHz subchannel shall be applied starting from the lowest 20 MHz subchannel in frequency: [c80 c80], where c80 is the phase rotation per 20 MHz subchannel for 80 MHz transmissions. Youhan Kim, et al.

  19. Straw Poll #4 • Do you support adding the following item into the specification framework document, 11-09/0992? • 3.2.4.3 OFDM modulation • For 160 MHz VHT transmissions, the same phase rotation per 20 MHz subchannel used for preamble portion of the VHT packet shall also be applied to the data symbols. Specifically, the following phase rotation per 20 MHz subchannel shall be applied to the data symbols, starting from the lowest 20 MHz subchannel in frequency: [c80 c80], where c80 is the phase rotation per 20 MHz subchannel for 80 MHz transmissions. Youhan Kim, et al.

  20. Straw Poll #5 • Do you support adding the following item into the specification framework document, 11-09/0992? • 3.2.4.2 Pilot subcarriers • The draft specification shall have 16 pilot subcarriers, with the subcarrier indices {±25, ±53, ±89, ±117, ±139, ±167, ±203}, for 160 MHz VHT transmissions. The pilot sequence and mapping for 160 MHz VHT transmissions shall be obtained by repeating the 80 MHz pilot sequence and mapping twice in frequency. Specifically, the pilot sequence for the nth symbol shall be as follows, where n is the 80 MHz pilot pattern: Including the pseudo random scrambling sequence, the pilot value for the kth tone, with k = {±25, ±53, ±89, ±117, ±139, ±167, ±203}, is pn+zPnk, where z = 4 for VHT, and pn is defined in Section 17.3.5.9 of IEEE802.11. Note that this does not include the phase rotation per 20 MHz subchannel yet. Youhan Kim, et al.

  21. References [1] Stacey, R. et al., Specification Framework for TGac, IEEE 802.11-09/0992r11, May 2010 [2] Vermani, S. et al, VHT-LTF sequence for 80 MHz, IEEE 802.11-10/0802r0, July 2010 [3] Zheng, J. et al., VHT-STF for 11AC, IEEE 802.11-10/0843r0, July 2010 [4] Shi, K. et al., Phase Tracking During VHT-LTF, IEEE 802.11-10/0771r0, July 2010 [5] Van Zelst, A. et al., Pilot Sequence for VHT-DATA, IEEE 802.11-10/0811r0, July 2010 Youhan Kim, et al.

  22. Backup Youhan Kim, et al.

  23. PAPR of 160MHz Preamble Each element in C is applied to one 20MHz segment C(1) is applied to most negative 20MHz segment

  24. CDF of Power of Data and VHT-LTF (160MHz)

  25. CDF of Power of Data and VHT-LTF (160MHz, zoomed)

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