1. doc.: IEEE 802.11-13/0525r1 SubmissionSlide 1 OBSS Mitigation Date: 2013-05-11 Authors: Chao-Chun Wang, MediaTek May 2013 NameAffiliationsAddressPhoneEmail Shoukang ZhengI2R1 Fusionopolis Way, Singapore +65 6408 2252skzheng@i2r.a-star.edu.sg Zander LeiI2R Li Chia ChooI2R Haiguang WangI2R Yuan ZhouI2R Yeow Wai LeongI2R Huai-Rong ShaoSamsung Chiu NgoSamsungchiu.ngo@samsung.com ChaoChun WangMediaTekSan Jose, CA, USA+1-408-526-1899chaochun.wang@mediatek.com James WangMediaTekSan Jose, CA, USAjames.wang@mediatek.com Jianhan LiuMediaTekSan Jose, CA, USAjianhan.liu@mediatek.com James YeeMediaTekHsinchu, Taiwanjames.yee@mediatek.com Thomas PareMediaTekthomas.pare@mediatek.com Kiran UlnMediaTekkiran.uln@mediatek.com Eric WongBroadcomSunnyvale, CA, USA+1-408-922-6672ewong@broadcom.com Matthew FischerBroadcomSunnyvale, CA, USA+1-408-543-3370mfischer@broadcom.com Minyoung ParkIntelHillsboro, OR, USA+1-503-712-4705minyoung.park@intel.com Tom TetzlaffIntelthomas.a.tetzlaff@intel.com Emily QiIntelHillsboro, OR, USAemily.h.qi@intel.com

2. doc.: IEEE 802.11-13/0525r1 Submission March 2013 Authors: NameAffiliationsAddressPhoneEmail Hongyuan ZhangMarvell Santa Clara, CA, USA+1-408-222-1837hongyuan@marvell.com Su Khiong YongMarvell Santa Clara, CA, USAskyong@marvell.com Sudhir SrinivasaMarvellSanta Clara, CA, USAsudhirs@marvell.com George CalcevHuaweiRolling Meadows, IL, USA george.calcev@huawei.com Osama Aboul MagdHuaweiOttawa, Canadaosama.aboulmagd@huawei.co m Young Hoon KwonHuaweiSan Diego, CA, USAyounghoon.kwon@huawei.com Betty ZhaoHuaweiBeijing, China+86-10-59728332betty.zhao@huawei.com David Xun YangxunHuaweiShenzhen, Chinadavid.yangxun@huawei.com Bin ZhenHuaweiShenzhen, Chinazhenbin@huawei.com Yongho SeokLG Electronics LG R&D Complex, Anyang, Korea +82-42-450-1947yongho.seok@lge.com Jeongki KimLG ElectronicsAnyang, Koreajeongki.kim@lge.com Jinsoo ChoiLG ElectronicsAnyang, Koreajinsoo.choi@lge.com Hangyu ChoLG ElectronicsAnyang, Koreahg.cho@lge.com Sun, Bo ZTEXi’an, Chinasun.bo1@zte.com.cn Lv, Kaiying ZTEXi’an, Chinalv.kaiying@zte.com Simone MerlinQualcommSan Diego, CA, USA+1-858-845-1243smerlin@qti.qualcomm.com Santosh AbrahamQualcommSan Diego, CA, USAsabraham@qti.qualcomm.com Menzo WentinkQualcommBreukelen, Netherlandsmwentink@qca.qualcomm.com Alfred AsterjadhiQualcommSan Diego, CA, USAaasterja@qti.qualcomm.com Amin JafarianQualcommSan Diego, CA, USAjafarian@qti.qualcomm.com Hemanth SampathQualcommSan Diego, CA, USAhsampath@qti.qualcomm.com VK jonesQualcommSanta Clara, CA, USAvkjones@qca.qualcomm.com Bin TianQualcomm George CherianQualcomm Slide 2Chao-Chun Wang, MediaTek

3. doc.: IEEE 802.11-13/0525r1 Submission March 2013 Authors: NameAffiliationsAddressPhoneEmail Sayantan ChoudhuryNokiaBerkeley, CA, USAsayantan.choudhury@nokia.com Klaus DopplerNokiaBerkeley, CA, USAklaus.doppler@nokia.com Chittabrata GhoshNokiaBerkeley, CA, USA+1-650-200-7566chittabrata.ghosh@nokia.com Esa TuomaalaNokiaBerkeley, CA, USA Ken MoriPanasonicOsaka, Japanmori.ken1@jp.panasonic.com Rojan ChitrakarPanasonic Tai Seng Ave, Singapore +65-6550-5347 rojan.chitrakar@sg.panasonic.com Minho CheongETRI 138 Gajeong-no, Yuseong-gu, Daejeon, Korea +82-42-560-5635minho@etri.re.kr Hyoung Jin KwonETRIDaejeon, Korea+82-42-860-1698kwonjin@etri.re.kr Jae Seung LeeETRIDaejeon, Korea+82-42-860-1326jasonlee@etri.re.kr Jae Woo ParkETRIDaejeon, Korea+82-42-860-5723parkjw@etri.re.kr Sok-kyu LeeETRIDaejeon, Korea+82-42-860-5919sk-lee@etri.re.kr Anna PantelidouRenesas Mobile Oulu, Finland +358-50-410-5316 anna.pantelidou@renesasmobile.c om Juho PirskanenRenesas Mobile Oulu, Finland +358-50-363-6632 juho.pirskanen@renesasmobile.co m Timo KoskelaRenesas Mobile Oulu, Finland +358-50-487-6991timo.koskela@renesasmobile.com Liwen ChuSTMicroelectronics Santa Clara, CA, USA +1-408-467-8436liwen.chu@st.com George VlantisSTMicroelectronics Santa Clara, CA, USA +1-408-893-9357george.vlantis@st.com Slide 3Chao-Chun Wang, MediaTek

4. doc.: IEEE 802.11-13/0525r1 Submission 11ah OBSS issue A long range BSS may enclose and overlap spatially with several short range BSSs An STA L associated with the long range AP L that is not within the coverage of one or more short range BSSs. –An STA O associated with the long range AP L that is also overlapped within the coverage of a short range BSS. An STA S is associated with a short range AP S that is also within the coverage of a long range BSS Slide 4 May 2013 AP S STA L STA O STA S Chao-Chun Wang, MediaTek

5. doc.: IEEE 802.11-13/0525r1 Submission 11ah OBSS issue - Continue A long range BSS has a coverage area radius that is multiples of that of a short range BSS. –A long range BSS has narrow 1 or 2 MHz channel bandwidth, while a short range BSS has wider bandwidth, such as 2, 4, 8 MHz A STA S is capable of receiving 1 and 2 MHz frames and a STA L is capable of receiving 1 MHz frames only Without loss of generality, we assume –the long range BSS occupies a 2 MHz channel and each short range BSS occupy 8 MHz band, consisting of four 2 MHz band. In the short range BSS, the protection period is set up by using duplicate RTS/CTS –The RTS/CTS has range covering the short range BSS only Slide 5 May 2013 Chao-Chun Wang, MediaTek

6. doc.: IEEE 802.11-13/0525r1 Submission Setting TXOP for STA s using duplicate RTS/CTS A transmitting STA s sends duplicate RTS frames to all 2 MHz sub-channels, primary and secondary. In response, duplicate CTS frames are sent to all usable 2MHz sub-channels –The receiver decides the best usable channel bandwidth based on the channel measurements prior to the receiving of duplicate RTSs The transmitter exchanges frames with the receiver by using the bandwidth indicated in the duplicate CTS. –Duplicate ACKs are returned on primary and all usable secondary channels Slide 6 May 2013 Chao-Chun Wang, MediaTek

7. doc.: IEEE 802.11-13/0525r1 Submission Problem Statement - 1 Slide 7 May 2013 Non-overlapping (in frequency domain) long range BSSs enclosing multiple non-overlapping (in spatial domain) short range BSSs –A short range BSS and a long range BSS that share the primary channel co-exist according to the current channel access rule. –The AP s s and STA s s will hear the traffic of a long range BSS sharing the primary channel and set up a NAV for collision avoidance scheme accordingly. The AP L s and STA L s on the secondary channels may not hear the traffic or TXOP set up in a short range BSS sharing the primary channel and may interfere with the traffic in the short range BSS. Chao-Chun Wang, MediaTek

8. doc.: IEEE 802.11-13/0525r1 Submission Problem Statement - 2 Slide 8 May 2013 Long range BSSs on the secondary channels of a short range BSS may not hear TXOP set up of the short range BSS and will access channel according to CCA rules –As a result, the traffic in the long range BSSs occupying secondary channels may collide with the traffic in short range BSSs and causes data loss. –In response, the STA S and STA L may re-transmit and continue to collide. With information about the condition of secondary channels, the re- transmission process will converge faster STA L and STA S need to co-exist fairly Chao-Chun Wang, MediaTek

9. doc.: IEEE 802.11-13/0525r1 Submission Secondary Channel Interference Slide 9 May 2013 Long range STA L s exchange RTS/CTS in a 1 or 2 MHz channel to set up a TXOP in a secondary channel. –The TXOP of the long range BSS overlaps with the TXOP set up by the short range BSSs Long range STA L s and short range STA S s exchange frames around the same time. –The collision may not affect the STA L s in the secondary channel but will corrupt data destined for the STA S s. The STA S receiver can estimates the interference level of the secondary channels based on Rx statistics –It is a vendor specific capability. It is up to a vendor to decide how or whether to support it Chao-Chun Wang, MediaTek

10. doc.: IEEE 802.11-13/0525r1 Submission Usable Channel Indication by using duplicate ACKs Slide 10 May 2013 An STA S transmitter starts transmitting using the primary channel and all secondary channels available. A STA S returns duplicate ACKs with reduced bandwidth to the transmitter –The transmitter can avoid the secondary channels with the high level of interference in the succeeding transmission –The STA s s will not interfere STA l s sharing a second channel Duplicate ACKs to reduce the channel bandwidth –The receiver returns duplicate short ACKs on the primary and usable secondary channels only. –Only return duplicate short ACKs on contiguous channels Subsequently, the STA S transmitter data only on the secondary channel indicated as usable by duplicate ACKS. Chao-Chun Wang, MediaTek

11. doc.: IEEE 802.11-13/0525r1 Submission Straw Poll Slide 11 May 2013 Do you support the inclusion of the usable channel indication mechanism follows and includes transmitter and receiver capability information When the data is received correctly by a receiver: –The receiver returns full bandwidth >= 2MHz short ACK on the primary and usable secondary channels. –Only return full bandwidth >= 2MHz short ACKs on contiguous channels Chao-Chun Wang, MediaTek