Preamble for 120MHz Date: 2010-11-10 Authors: Nov, 2010 Month Year doc.: IEEE 802.11-yy/xxxxr0 Nov, 2010 Preamble for 120MHz Date: 2010-11-10 Authors: Sun Bo, ZTE Corporation John Doe, Some Company

Month Year doc.: IEEE 802.11-yy/xxxxr0 Nov, 2010 Abstract In R3.1.E: The draft specification shall include support for an efficient channelization in China’s (5,725 ~ 5,850 MHz) spectrum. 802.11ac is supposed to provide very high throughput, which requires to use wideband as much as possible. Following the Chinese spectrum and the existing 11ac tone allocations, we propose 802.11ac to support the 120 MHz PHY transmission. Preamble have been defined for 80MHz and 160MHz (see ref. [1]). To support potential 120MHz transmission, this proposal put forward some preamble designs for 120MHz transmission. Sun Bo, ZTE Corporation John Doe, Some Company

120MHz PHY Transmission Nov, 2010 Month Year doc.: IEEE 802.11-yy/xxxxr0 Nov, 2010 120MHz PHY Transmission Two feasible options for 120MHz PHY transmission: Option 1: Tone allocation for 120 MHz transmissions consists of one 80 MHz tone and one 40 MHz tone allocation in frequency. Option 2: Tone allocation for 120 MHz transmissions consists of a single120 MHz tone allocation in frequency. To acquire more data tones and higher throughput, we prefer a single120 MHz tone allocation in frequency. Sun Bo, ZTE Corporation John Doe, Some Company

Non-VHT portion of VHT mixed format preamble (1) Nov, 2010 Non-VHT portion of VHT mixed format preamble (1) Cyclic shift definition The CSD (Cyclic Shift Diversity) values for up to 4 antennas in L-STF, L-LTF, and L-SIG are the same as the CSD values for the non-HT portion of the packet defined in Table 20-8 of Std 802.11n-2009. L-STF definition The 20 MHz L-STF pattern in the VHT preamble is as defined in 20.3.9.3.3 of Std 802.11n-2009. The L-STF pattern for 120 MHz VHT transmissions shall repeat 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: [c120], where c120 is the phase rotation per 20 MHz subchannel for 120 MHz transmissions and explained in the slide 13 . Slide 4 Sun Bo, ZTE Corporation

Non-VHT portion of VHT mixed format preamble (2) Nov, 2010 Non-VHT portion of VHT mixed format preamble (2) L-LTF definition The 20 MHz L-LTF pattern in the VHT preamble is as defined in 20.3.9.3.4 of Std 802.11n-2009. The 20 MHz L-LTF pattern in the VHT preamble is as defined in 20.3.9.3.3 of Std 802.11n-2009. The L-LTF pattern for 120 MHz VHT transmissions shall repeat the 11n 20 MHz L-LTF pattern 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: [c120]. L-SIG definition The 20 MHz L-SIG pattern in the VHT preamble is as defined in 20.3.9.3.3 of Std 802.11n-2009. The L-SIG for 120 MHz VHT transmissions shall repeat the 11n 20 MHz L-SIG pattern 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: [c120]. Slide 5 Sun Bo, ZTE Corporation

VHT portion of VHT mixed format preamble Nov, 2010 VHT portion of VHT mixed format preamble Cyclic shift definition The CSD (Cyclic Shift Diversity) values for up to 4 antennas in VHT-SIG-A are the same as the CSD values for the non-HT portion of the packet defined in Table 20-8 of Std 802.11n-2009. The CSD (Cyclic Shift Diversity) values for more larger than 4 antennas in VHT-SIG-A are the same as the CSD values for the VHT portion of the packet defined as3.2.3.2.1 in [1]. VHT-SIG-A definition The content of VHT-SIG-A is same as 3.2.3.2.2 in [1] except to increase 1 reserved bit for 120MHz bandwidth indication (see ref. [3]). Slide 6 Sun Bo, ZTE Corporation

VHT-STF of 120MHz preamble Nov, 2010 VHT-STF of 120MHz preamble VHT-STF definition The 20 MHz L-STF pattern in the VHT preamble is as defined in 20.3.9.3.3 of Std 802.11n-2009. The frequency domain sequence used to construct the VHT-STF in 20 MHz transmission is identical to the L-STF; in 120 MHz transmission, the VHT-STF is constructed from the 20 MHz version by replicating it in each 20 MHz band, frequency shifting, and applying the following phase rotation per 20 MHz subband starting from the lowest 20 MHz subchannel in frequency: [c120] . VHT-STF frequency sequence without rotating phase : VHT-STF-186,186={L-STF-58，58，0，0，0，0，0，0，0，0，0，0，0，VHT-STF-122，122} Slide 7 Sun Bo, ZTE Corporation

VHT portion of VHT mixed format preamble Nov, 2010 VHT portion of VHT mixed format preamble VHT-LTF definition The 20 MHz L-LTF pattern in the VHT preamble is as defined in 20.3.9.3.3 of Std 802.11n-2009. The frequency domain sequence used to construct the VHT-LTF in 20 MHz transmission is identical to the L-LTF; 120MHZ VHT-LTF use all 11n20 tones on both 20 MHz subchannels with filling of missing tones and applying a phase rotation on each 20MHz subchannel . Slide 8 Sun Bo, ZTE Corporation

VHT LTF sequence structure Nov, 2010 VHT LTF sequence structure Assume that the VHT-LTF sequence is constructed by Slide 9 Sun Bo, ZTE Corporation

VHT LTF sequence structure Nov, 2010 VHT LTF sequence structure Assuming the VHT-LTF structure of previous slide, to minimize the PAPR, we need to optimize Missing tone values 20 MHz phase rotations, [c1 c2 c3 c4 c5 c6] where S are 20MHz phase rotations, and interp120NullL, interp120NullR are LTF sequences for all possible missing tone values. For VHT-LTF, pilot tones are multiplied by an R value, while other tones are multiplied by a P value. P, R is defined in [2]. Missing tones interp40NullL(3 tones), interp120ExtraL (4 tones), interp120ExtraR (4 tones) , interp40NullR(3 tones) interp40NullL= interp40NullR=[1 -1 1], as defined in 20.3.9.3.3 of Std 802.11n-2009. [c1 c2 c3 c4 c5 c6] is the phase rotation pattern consisting of {1, -1, j, -j} values。 Slide 10 Sun Bo, ZTE Corporation

Optimal Phase rotation and VHT-LTF sequence Nov, 2010 Optimal Phase rotation and VHT-LTF sequence The parameters which result in the optimal VHT-LTF Phase rotation [c1 c2 c3 c4 c5 c6] = [1 j -1 –j -1 j]; [interp120ExtraL, interp120ExtraR] = [1 1 -1 -1, 1 1 1 -1] Phase Rotations per 20 MHz band PAPR (2x oversampled) L-STF L-LTF VHT-LTF120 [c1 c2 c3 c4 c5 c6] = [1 1 1 1 1 1] 9.87 dB 11.36 dB 10.18 dB [c1 c2 c3 c4 c5 c6] = [1 j 1 j 1 j] 6.86 dB 8.56 dB 8.30 dB [c1 c2 c3 c4 c5 c6] = [1 -1 -1 -1 1 j] 4.33 dB 6.12 dB 6.43 dB [c1 c2 c3 c4 c5 c6] = [1 j -1 -j -1 j] 3.47 dB 5.5 dB 4.86 dB Slide 11 Sun Bo, ZTE Corporation

Optimal VHT-LTF sequence Nov, 2010 Optimal VHT-LTF sequence Optimal VHT-LTF frequency sequence (excluding phase rotation per 20 MHz subchannel) is Slide 12 Sun Bo, ZTE Corporation

Phase Rotation for preamble and data tones Nov. 2010 Phase Rotation for preamble and data tones In all elements of an 120 MHz VHT PPDU , i.e., the L-STF, L-LTF, L-SIG, VHT-SIG-A, VHT-LTFs, VHT-SIG-B and the Data, subcarrier k, where , shall be multiplied by the following function of k, prior to transmission: Slide 13 LvKaiying, ZTE Corporation

Nov, 2010 References [1] Stacey, R. et al., Specification Framework for TGac, IEEE 802.11-09/0992r11, May 2010. [2] IEEE Std 802.11n-2009. [3] 10/XXXXr0, “signal fields design for 120MHz bandwidth”. Slide 14 Sun Bo, ZTE Corporation

Nov, 2010 Thank you! Sun Bo, ZTE Corporation