doc.: IEEE 802.11-12/1302r0

Submission

November 2012

Yongho Seok, LG ElectronicsSlide 1

TXOP Truncation

Date: 2012-11-12Authors:

Name Affiliations Address Phone Email

Yongho Seok LG ElectronicsLG R&D Complex

Anyang-Shi, Kyungki-Do, Korea

+82-31-450-1947 yongho.seok@lge.com

Minyoung Park Intel Hillsboro, OR +1 503 712 4705 minyoung.park@intel.comMatthew Fischer Broadcom mfischer@broadcom.comJinsoo Choi LG ElectronicsJeongki Kim LG ElectronicsHangyu Cho LG ElectronicsEric Wong Broadcom Sunnyvale, CA +1 408 922 6672 ewong@broadcom.comTom Tetzlaff IntelEmily Qi IntelSimone Merlin Qualcomm San Diego, CA +1 858 845 1243 smerlin@qualcomm.comAmin Jafarian QualcommBin Tian QualcommSantosh Abraham QualcommMenzo Wentink QualcommHemanth Sampath QualcommVK jones Qualcomm

doc.: IEEE 802.11-12/1302r0

Submission Slide 2

Name Affiliations Address Phone EmailYong Liu Marvell Hongyuan Zhang MarvellSudhir Srinivasa MarvellGeorge Calcev Huawei Rolling Meadows, IL,

USAGeorge.Calcev@huawei.com

Osama Aboul Magd HuaweiYoung Hoon Kwon HuaweiBetty Zhao HuaweiDavid Yangxun Huawei

Bin Zhen Huawei

ChaoChun Wang MediaTekJames Wang MediaTekJianhan Liu MediaTekVish Ponnampalam MediaTekJames Yee MediaTekHuai-Rong Shao   Samsung ElectronicsChiu Ngo Samsung ElectronicsMinho Cheong ETRIJae Seung Lee ETRIHyoungjin Kwon ETRIJaewoo Park ETRISok-kyu Lee ETRISun, Bo         ZTELv, Kaiying         ZTE

Authors:

November 2012

Yongho Seok, LG Electronics

doc.: IEEE 802.11-12/1302r0

Submission Yongho Seok, LG ElectronicsSlide 3

Authors:Name Affiliations Address Phone Email

Sayantan Choudhury NokiaKlaus Doppler NokiaChittabrata Ghosh NokiaEsa Tuomaala NokiaKen Mori PanasonicRojan Chitrakar PanasonicHaiguang Wang I2RShoukang Zheng I2RYeow Wai Leong I2RZander Lei I2RJaya Shankar I2RAnh Tuan Hoang I2RJoseph Teo Chee Ming I2RAnna Pantelidou Renesas MobileJuho Pirskanen Renesas MobileTimo Koskela Renesas MobileLiwen Chu STMicroelectronicsGeorge Vlantis STMicroelectronics

November 2012

doc.: IEEE 802.11-12/1302r0

Submission

Channel Access in Restricted Access Window

Beacon Interval

Restricted Access Window (RAW)

Slot Boundary

Slot Boundary

Slot Boundary

Slot Boundary

Slot Boundary

Slot Boundary

Slot duration

• A Restricted Access Window (RAW) is divided in time slots.• STA wakes up at TBTT and it listens to a Beacon frame that indicates the

slot duration for each Restricted Access Window (RAW). • STA determines its channel access slot assigned by AP. • STA may sleep before its channel access slot.• STA shall start to access the channel at the slot boundary of its channel

access slot based on EDCA. • AP may protect the PS-Poll/Trigger frames by setting the NAV

Slide 4 Yongho Seok, LG Electronics

November 2012

doc.: IEEE 802.11-12/1302r0

Submission Yongho Seok, LG Electronics

November 2012

Slide 5

• When a STA gains access to the channel using EDCA and empties its transmission queue, it may transmit a CF-End frame provided that the remaining duration is long enough to transmit this frame. By transmitting the CF-End frame, the STA is explicitly indicating the completion of its TXOP.

• A STA shall interpret the reception of a CF-End frame as a NAV reset, i.e., it resets its NAV timer to 0 at the end of the PPDU containing this frame. After receiving a CF-End frame with a matching BSSID, an AP may respond by transmitting a CF-End frame after SIFS.

Channel Access in Restricted Access Window

doc.: IEEE 802.11-12/1302r0

Submission

• When CF-END inside RAW is used to truncate the TXOP of the granted STAs, it also makes to reset the NAV of 3rd party STAs.

Motivation

Beacon

Restricted Access Window

RTS

CTS

DATA DATA

ACK

CF-END

NAV

NAV

CTS

GrantedSTA1 (assigned slot1)

GrantedSTA2 (assigned slot 1)

3rd party STA

Reset NAV

Reset NAV

RTS

TXOP Limit

Slot 1Slot 0

Yongho Seok, LG Electronics

November 2012

Slide 6

doc.: IEEE 802.11-12/1302r0

Submission Yongho Seok, LG Electronics

November 2012

Slide 7

• Duration field value of CF-END frame is set to either zero or a truncated time.

• If the Duration field value of the received CF-END frame is set to zero, then all STAs reset its NAV.

• Else if the Duration field of the received CF-END frame is matched with the local NAV of a STA, then the STA resets its NAV.

• The matching condition allows for a tolerance of +/- TBD microsecond. • Else the received CF-END frame is discarded.

Proposal

doc.: IEEE 802.11-12/1302r0

Submission

Beacon

Restricted Access Window

RTS

CTS

DATA DATA

ACK

CF-END

NAV

NAV

CTS

GrantedSTA1 (assigned slot1)

GrantedSTA2 (assigned slot 1)

3rd party STA

TXOP Limit

Slot 1Slot 0

Reset NAV

Duration

Discard CF-END

RTS

Yongho Seok, LG Electronics

November 2012

Slide 8

• Overall procedure of TXOP truncation in RAW.• Depending on the Duration field value of CF-END, STAs have two different

behaviors of resetting NAV.

Proposal (example)

doc.: IEEE 802.11-12/1302r0

Submission

DATA

ACK

CF-END

NAV

NAV

CTS

DATA

ACK CF-END

Reset NAV

RTS

NAV

Restricted Access Window

GrantedSTA1 (assigned to last slot N)

GrantedSTA2 (assigned to last slot N)

3rd party STA

Reset NAV

Reset NAV

Reset NAV

Duration

Discard CF-END

RTS

Duration

Yongho Seok, LG Electronics

November 2012

Slide 9

• Overall procedure of TXOP truncation in RAW.• Depending on the Duration field value of CF-END, STAs have two different

behaviors of resetting NAV.

Proposal (example)

doc.: IEEE 802.11-12/1302r0

Submission Yongho Seok, LG Electronics

November 2012

Slide 10

Proposal (example)

doc.: IEEE 802.11-12/1302r0

Submission Yongho Seok, LG Electronics

November 2012

Slide 11

Conclusion

• In 802.11ah, we defined a restricted access window.• During the restricted access window, only granted STAs access the

channel using EDCA. But, the non-granted STAs set the NAV for the duration of the restricted access window.

• Motivation of this contribution is • Inside the RAW, CF-END frame used for truncating TXOP does not reset the

NAV of the non-granted STAs • For this purpose, we proposed to define two different behaviors of

resetting the NAV

doc.: IEEE 802.11-12/1302r0

Submission Yongho Seok, LG Electronics

November 2012

Slide 12

Straw Poll 1

• Do you support the following CF-END rule ?• Duration field value of CF-END frame is set to either zero or a

truncated time.• If the Duration field value of the received CF-END frame is set to

zero, then all STAs reset its NAV.• Else if the Duration field of the received CF-END frame is matched

with the local NAV of a STA, then the STA resets its NAV. • The matching condition allows for a tolerance of +/- TBD microsecond.

• Else the received CF-END frame is discarded.

doc.: IEEE 802.11-12/1302r0

Submission

RTS

CTS

DATA DATASTA3(BSS2)

DATA DATA

ACK

CF-END

NAV

CTS

STA1(BSS1)

STA2(BSS1)

Reset NAV

AP1(BSS1)

AP2(BSS2)

NAV

RTS DATA DATA

ACK

DATA DATA

Collision

ACK

NAV

Yongho Seok, LG Electronics

November 2012

Slide 13

Backup

• In OBSS environment, CF-END frame makes to reset the NAV set by other BSS.

doc.: IEEE 802.11-12/1302r0

Submission

STA3(BSS2) RTS

CTS

DATA DATA

DATA DATA

ACK

CF-END

NAV

STA1(BSS1)

STA2(BSS1)

Discard CF-END

AP1(BSS1)

AP2(BSS2)

NAV

ACK

DATA DATA

Duration

RTS

CTS

DATA DATA

Yongho Seok, LG Electronics

November 2012

Slide 14

Backup

• But, if we use the proposed CF-END rule (defined in slide 7), we can solve the problem of resetting the NAV.