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Making the Quiet Channel Element Work for 11a/11n Clients

Making the Quiet Channel Element Work for 11a/11n Clients. Date: 2011-09-30. Slide 1. Overview. Situation Quiet Element in 11n quiets legacy devices throughout the BSS bandwidth when needed Quiet Chanel Element was added in 11ac [2] to allow quieting secondary80 channel Problem

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Making the Quiet Channel Element Work for 11a/11n Clients

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  1. Making the Quiet Channel Element Work for 11a/11n Clients Date: 2011-09-30 Slide 1 Brian Hart, Cisco Systems

  2. Overview • Situation • Quiet Element in 11n quiets legacy devices throughout the BSS bandwidth when needed • Quiet Chanel Element was added in 11ac [2] to allow quieting secondary80 channel • Problem • Quiet Channel element is paired with Quiet element, which unnecessarily quiets 11a/11n devices operating in primary and primary40 channels of a 80+80 MHz or 160 MHz BSS • Quiet Channel element has a redundant field • Solution • We propose to remove the need for pairing Quiet Channel element with Quiet element, in order to avoid quieting legacy devices unfairly • We propose required format changes

  3. Situation • TGac recently added Quiet Channel element to quiet secondary80 channel in 80+80 MHz or 160MHz BSS [2] • Quiet Channel element has the following structure and needs to be paired with Quiet element • The BSS Usable Channel Width field, which is 1 octet in length, indicates the only allowed channel bandwidth in use by STAs within the BSS during the intervals indicated by the Quiet element. The field value is set to 0 for primary 80MHz. Values in the range 1 to 255 are reserved. • The AP Quiet Mode field specifies STA behavior during the quiet intervals. When communications to the AP are allowed on the channel indicated by the BSS Usable Channel Width field, the AP Quiet Mode field is set to 1. Otherwise, it is set to 0.

  4. Problem • The recently-added Quiet Channel element is paired with Quiet element • Sending Quiet Channel element along Quiet element quiets legacy devices in the use case where AP can continue operation in the primary80 • In this use case, since AP continues operation in the primary80, the legacy devices can still continue operation in primary or primary40 channels, however as the result of transmission of Quiet element , the legacy devices unnecessarily and unfairly are quieted • Current frame format of Quiet Channel has a redundant field • During TGac meeting in September this issue was raised and it was agreed by the stakeholders to further improve the frame format

  5. Solution • We propose to a mode for the Quiet Channel element where it is sent standalone • This would only quiet the secondary80 channel of the BSS, without affecting legacy devices • 11ac and 11a/11n devices continue to use primary, primary40, and primary80 channels • We also propose to remove the redundant BSS Usable Channel Width field in Quiet Channel element in [2] • In our proposed solution, the Quiet Channel element is used to Either • Quiet secondary80, but all frames exchanges in primary80 are allowed (AP Quiet Mode = 1) • In this case Quiet Channel element(s) with AP Quiet Mode=1 are sent as standalone element(s); there is no need to also send Quiet element(s) for legacy devices (and they remain unaffected by quieting secondary80 channel) • This case is useful when concurrent transmit and radar detection is implemented in AP Or • Quiet the secondary80 and prohibit transmissions targeted to AP in primary80 (AP Quiet Mode=0) • In this case one Quiet Channel element with AP Quiet Mode=0 is paired with Quiet element(s). • This case is useful when concurrent transmit and radar detection is not implemented in AP. Clients are allowed to communicate by DLS or TDLS in primary80 Or a Beacon/Probe Response can simultaneously include both mechanisms

  6. Proposal for Quiet Channel Element Format • AP Quiet Mode = 0: Quiet Channel element is sent with Quiet element(s) • AP Quiet Mode = 1: Quiet Channel element(s) are sent standalone • Quiet Count: The Quiet Count field is set to the number of TBTTs until the beacon interval during which the next quiet interval for secondary80 starts. A value of 1 indicates the quiet interval starts during the beacon interval starting at the next TBTT. A value of 0 is reserved. • Quiet Period: The Quiet Period field is set to the number of beacon intervals between the start of regularly scheduled quiet intervals defined by this Quiet Channel element. A value of 0 indicates that no periodic quiet interval is defined. • Quiet Duration: The Quiet Duration field is set to the duration of the quiet interval for secondary80, expressed in TUs. • Quiet Offset: The Quiet Offset field is set to the offset of the start of the quiet interval for secondary80 from the TBTT specified by the Quiet Count field, expressed in TUs. The value of the Quiet Offset field is less than one beacon interval.

  7. Summary • We outlined details of the problem in the recently-added Quiet Channel element • We proposed to allow Quiet Channel element to be sent standalone in order to avoid unnecessarily quieting legacy devices • We provided the proposed changes to the frame format of the Quiet Channel element

  8. Straw Poll • Do you support to the changes proposed in slide 6 • Y • N • A

  9. Reference [1] 20101012r2 Cisco; FCC 5 GHz contiguous unlicensed spectrum [2] 11-11-1322-02-00ac-d1-comment-resolution-quiet-element LG

  10. Backup LG

  11. 2 W EIRP 5 GHz license-exempt spectrum details [1] China India Campus/Indoor 200 mW EIRP Campus/Indoor 200 mW EIRP Japan Indoor 200 mW EIRP Outdoor 1 WEIRP 5.875 5.725 USA/Canada Indoor Part 87F/80.375 DSRC250 mW Outdoor 1 WEIRP 4 W EIRP 5.725 5.470 Europe Indoor 200 mW EIRP Outdoor 1W EIRP 2 W EIRP/ DFS&TPC 5.100 5.300 5.400 5.500 5.600 5.700 5.800 5.900 5.200 DFS & TPC DFS & TPC required world wide Slide 11 Peter Ecclesine, Cisco

  12. Quieting in DFS Bands • Observing rules for DFS bands, AP usually quiets the whole band • E.g. by sending Quiet Element • However, in the case of 160MHz operation WLAN can continue operation by switching to 80MHz operation • The following shows the relevant cases 36 40 44 48 52 56 60 64 100 104 108 112 116 120 124 128 132 136 140 144 149 153 157 161 Primary80 Contiguous 160 MHz BSS Primary80 Primary80 Non-Contiguous 160 MHz Primary80 Primary80 Primary80 Primary80 Primary80 36 40 44 48 52 56 60 64 100 104 108 112 116 120 124 128 132 136 140 144 149 153 157 161 165 IEEE channel # 20 MHz 40 MHz 80 MHz 160 MHz UNII-2 DFS Band UNII-2 DFS Band UNII-1 UNII-3 Slide 12 Peter Ecclesine, Cisco

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