1. 80MHz/160MHz Protection Date: 2010-09-14 Authors: Date: September 2010
Feb, 2008
doc.: IEEE /xxxx
Date: September 2010
80MHz/160MHz Protection
Date:
Authors:
L. Chu et al
Liwen Chu, STMicroelectronics

2. HT TXOP Protection and Truncation
Date: September 2010
HT TXOP Protection and Truncation
802.11n introduces features that a legacy 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
ch1
ch0+ch1
ch0
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
Date: September 2010
802.11ac TXOP Protection and Truncation
802.11ac uses 80/160 MHz channels.
802.11ac introduces new features that legacy a STAs and n STAs can not understand: DL-MU MIMO, new ac preamble etc.
802.11ac TXOP should be protected by frames which can be understood by a STAs and n 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)
Date: September 2010
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.
RTS
A-MPDU
(VHT frame)
ch3
RTS
ch2
ch0+ch1+ch2+ch3
RTS
ch1
VHT-AP1
RTS
ch0
VHT-STA1
CTS
ch0
ch1
ch2
ch3
BLKACK
FC HT-STA3
Ch0+ch1+ch2+ch3
VHT-STA1
VHT-AP1
11a-AP2
FC HT-AP3
11a-STA2
ch0+ch1
ch0+ch1+ch2+ch3
ch3
11a–STA2
NAV
ch3
“ch0(primary channel)+ch1+ch2+ch3” is a 80MHz channel.
“ch0(primary channel)+ch1” is a 40MHz channel.
FC HT–STA3
NAV
ch0
ch3 is a 20MHz channel.

5. Negotiation of Used Channel Bandwidth (TBD)
Date: September 2010
Negotiation of Used Channel Bandwidth (TBD)
The TXOP holder and the TXOP responder notify the peer STA of the usage of channels for the following frame transmission through non-HT duplicate frame handshake. We call the two frames the non-HT duplicate initiating frame, the non-HT duplicate responding frame.
The selection of non-HT duplicate frames will allow legacy a, n device to set the NAV correctly.
The legacy devices will not delete the received frames per their frame receiving rules.
The TXOP holder transmits CF-End frame to truncate the TXOP through the same channel set that it transmits the non-HT duplicate initiating frame. And the TXOP responder transmits CF-End frame to truncate the TXOP through the same channel set that it transmits the non-HT duplicate responding frame.
The TXOP responder may transmit the non-duplicate responding frame by the subset of the channels that the TXOP holder transmits the non-HT duplicate initiating frame for TXOP-protection.

6. Updated RTS/CTS method (TBD)
Date: September 2010
Updated RTS/CTS method (TBD)
A RTS includes the candidate subchannel set in the reserved bits of Service field or PHY padding.
The TXOP holder selects the candidate subchannel set from the idle 20MHz operating channels that it detects.
A CTS includes final subchannel set in the reserved bits of Service field or PHY padding.
The final subchannel set must be the same as or subset of the candidate subchannel set. The final subchannel set must only include the idle 20MHz operating channels that the TXOP responder detects.
The final subchannel set is used for the following frame transmission in the TXOP.

7. Updated RTS/CTS method (Cont’d)(TBD)
Date: September 2010
Updated RTS/CTS method (Cont’d)(TBD)
A new control frame (VHT-RTS?) that uses non-HT duplicate format to initiate the TXOP includes candidate subchannel set.
The TXOP holder selects the candidate subchannel set from the idle 20MHz operating channels that it detects.
If the TXOP holder does not receive the responding control frame, it transmits CF-End to reset the neighbor STA’s NAV timer.
A new control frame (VHT-CTS?) that uses non-HT duplicate format to respond the initiating frame of the TXOP which includes final subchannel set.
The TXOP responder does not transmit respond frame if its NAV timer is not 0 or all the channels in the candidate subchannel set are busy.
If a VHT STA can not receive the non-HT duplicate responding frame, it will reset the NAV timer set by the non-HT duplicate initiating frame.
The final subchannel set must be the same as or subset of the candidate subchannel set. The final subchannel set must only include the idle 20MHz operating channels that the TXOP responder detects.
The final subchannel set is used for the following frame transmission in the TXOP.

8. Vender specific action/ACK method (TBD)
Date: September 2010
Vender specific action/ACK method (TBD)
A new Vender specific action frame that uses non-HT duplicate format to initiate the TXOP includes candidate subchannel set.
The TXOP holder selects the candidate subchannel set from the idle 20MHz operating channels that it detects.
If the TXOP holder does not receive the responding ACK/vender specific responding frame, it transmits CF-End to reset the neighbor STA’s NAV timer.
Option 1 of non-HT duplicate responding frame: An ACK that uses non-HT duplicate format to respond the initiating frame of the TXOP includes final subchannel set.
The TXOP responder does not transmit respond frame if its NAV timer is not 0 or all the channels in the candidate subchannel set are busy. This is the change to ACK rules.
If a VHT STA can not receive the non-HT duplicate responding frame, it will reset the NAV timer set by the non-HT duplicate initiating frame.
The final subchannel set must be the same or subset of the candidate subchannel set. The final subchannel set must only include the idle 20MHz operating channels that the TXOP responder detects.
The final subchannel set is used for the following frame transmission in the TXOP.

9. Vender specific action/ACK method (Cont’d) (TBD)
Date: September 2010
Vender specific action/ACK method (Cont’d) (TBD)
Option 2 of non-HT duplicate responding frame: A new Vender specific action frame that uses non-HT duplicate format to respond the initiating frame of the TXOP includes final subchannel set.
The TXOP responder does not transmit respond frame if its NAV timer is not 0 or all the channels in the candidate subchannel set are busy.
If a VHT STA can not receive the non-HT duplicate responding frame, it will reset the NAV timer set by the non-HT duplicate initiating frame.
The final subchannel set must be the same or subset of the candidate subchannel set. The final subchannel set must only include the idle 20MHz operating channels that the TXOP responder detects.
The final subchannel set is used for the following frame transmission in the TXOP.

10. 80MHz/160MHz non-HT Duplicate Transmission
Date: September 2010
80MHz/160MHz non-HT Duplicate Transmission
80MHz/160MHz Non-HT duplicate transmission is used to transmit to a, n 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 ac 80MHz/160MHz VHT transmission.
The VHT-SIG, VHT-STF, VHT-LTF are not transmitted.

11. Date: September 2010
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.