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80MHz/160MHz Protection

80MHz/160MHz Protection. Date: 2010-09-07. Authors:. HT TXOP Protection and Truncation. 802.11n introduces features that a legacy 802.11 STAs can not understand: 40MHz transmission, frame aggregation, short GI etc . 40MHz non-HT duplicate mode is used to protect the 11n transmission:

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80MHz/160MHz Protection

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  1. 80MHz/160MHz Protection Date: 2010-09-07 Authors: L. Chu et al

  2. HT TXOP Protection and Truncation • 802.11n introduces features that a legacy 802.11 STAs can not understand: 40MHz transmission, frame aggregation, short GI etc. • 40MHz non-HT duplicate mode is used to protect the 11n transmission: • Non-HT duplicate frames (e.g. RTS/CTS) are used to establish protection of its TXOP in two 20MHz channels, and • Non-HT duplicate CF-End frame are used to truncate the protect TXOP protected by non-HT duplicate frames. • To get a 40MHz EDCA based TXOP, a STA does EDCA backoff procedure in the primary channel, and detects the second channel being idle during PIFS interval before the TXOP. FC HT-STA1 RTS ch0 A-MPDU (HT frame) FC HT-AP1 ch0+ch1 RTS ch1 CTS ch0 BLKACK 11a-STA3 ch0+ch1 FC HT-AP1 11a-AP2 FC HT-STA1 11a-AP3 CTS ch1 11a-STA2 ch0 ch1 ch0+ch1 11a –STA2 NAV ch0 “ch0(primary channel)+ch1” is a 40MHz channel. ch0 is a 20MHz channel. 11a –STA3 NAV ch1 ch1 is a 20MHz channel.

  3. 802.11ac TXOP Protection and Truncation • 802.11ac uses 80/160 MHz channels. • 802.11ac introduces new features that legacy 802.11a STAs and 802.11n STAs can not understand: DL-MU MIMO, new 802.11ac preamble etc. • 802.11ac TXOP should be protected by frames which can be understood by 802.11a STAs and 802.11n STAs in each 20MHz channel. • 80MHz/160MHz non-HT duplicate frames are used for such TXOP protection/truncation: • 80MHz/160MHz non-HT duplicate frame duplicates 20 MHz non-HT transmission in each 20 MHz channel of a 80MHz/160MHz channel. • 80MHz/160MHz Non-HT duplicate frames (e.g. RTS/CTS) are used to establish protection of its TXOP in four 20MHz channels or in eight 20MHz channels, and • 80MHz/160MHz Non-HT duplicate CF-End frame is used to truncate the protect TXOP protected by non-HT duplicate frames in four 20MHz channels or in eight 20MHz channels.

  4. 802.11ac TXOP Protection and Truncation (Cont’d) • To get a 80MHz/160MHz EDCA based TXOP, a STA does EDCA backoff procedure in the primary channel, and detects the other 20MHz channels being idle during PIFS interval before the TXOP. CTS ch3 CTS RTS A-MPDU (VHT frame) ch2 ch3 CTS ch1 RTS ch2 ch0+ch1+ch2+ch3 CTS ch0 RTS ch1 VHT-AP1 RTS ch0 VHT-STA1 BLKACK FC HT-STA3 Ch0+ch1+ch2+ch3 VHT-STA1 VHT-AP1 11a-AP2 FC HT-AP3 11a-STA2 ch3 ch0+ch1 ch0+ch1+ch2+ch3 11a–STA2 NAV “ch0(primary channel)+ch1+ch2+ch3” is a 80MHz channel. ch3 “ch0(primary channel)+ch1” is a 40MHz channel. FC HT–STA3 NAV ch0 ch3 is a 20MHz channel.

  5. 80MHz/160MHz non-HT Duplicate Transmission • 80MHz/160MHz Non-HT duplicate transmission is used to transmit to 802.11a, 802.11n STAs that nay be present in a 20MHz/40MHz channel covered by 80MHz/160MHz channel. • The L-STF, L-LTF and L-SIG shall be transmitted in the same way as in the 802.11ac 80MHz/160MHz VHT transmission. • The VHT-SIG, VHT-STF, VHT-LTF are not transmitted.

  6. Straw Poll • Do you support adding the following item into the specification framework document, 11-09/0992? • R5.X: 80MHz/160MHz duplicate mode shall be included in the specification to protect 80MHz/160MHz transmission.

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