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20MHz Protection Mode Date: Authors: August 2008 Feb, 2008

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Presentation on theme: "20MHz Protection Mode Date: Authors: August 2008 Feb, 2008"— Presentation transcript:

1 20MHz Protection Mode Date: 2008-08-05 Authors: August 2008 Feb, 2008
doc.: IEEE /xxxx August 2008 20MHz Protection Mode Date: Authors: L. Chu Etc. Liwen Chu, STMicroelectronics

2 Current 20MHz Protection Mode in 11n Draft
August 2008 Current 20MHz Protection Mode in 11n Draft A 20MHz HT STA can not decode the received 40MHz HT frame, it invokes EIFS to protect the response transmission (See the resolution to comment 7040 in [1]). AP1 AP1 40MHzData (STA1) 40MHzData (STA1) 40MHzAP/STA 20MHzSTA STA1 ACK ACK STA1 STA2 STA2 EIFS EIFS Received corrupted frame L. Chu Etc.

3 Normal ACK Protection in 20/40MHz Infrastructure BSS
August 2008 Normal ACK Protection in 20/40MHz Infrastructure BSS EIFS based protection does not work if 40MHz AP1 is the receiver. Using NAV based protection, this will not occur. STA1 RTS 40MHzData (STA1) 40MHzData (STA1) AP1 CTS ACK AP1 EIFS EIFS 40MHzAP/STA STA2 Data (AP1) 20MHzSTA Backoff Backoff Failed normal ACK protection based on EIFS STA1 STA2 Received corrupted frame L. Chu Etc.

4 BlockAck Protection in 20/40MHz Infrastructure BSS
August 2008 BlockAck Protection in 20/40MHz Infrastructure BSS EIFS-based protection can not protect BlockAck transmission. Using NAV based protection, this will not occur. AP1 40MHzAP/STA 20MHzSTA STA1 STA2 BLKREQ STA1 RTS Data (AP1) Data (AP1) Data (AP1) AP1 CTS EIFS STA2 Data (AP1) Data (AP1) Backoff No ACK Backoff Failed blockack protection based on EIFS Received corrupted frame L. Chu Etc.

5 PSMP in 20/40MHz Infrastructure BSS
August 2008 PSMP in 20/40MHz Infrastructure BSS EIFS-based protection can not protect PSMP transmission. Using NAV based protection, this will not occur.. AP1 40MHzAP/STA 20MHzSTA STA1 STA2 AP1 PSMP 40MHz A-MPDU (STA1) STA1 40MHz A-MPDU (AP1) MTBA EIFS STA2 Data (AP1) Backoff Failed blockack protection based on EIFS Received corrupted frame L. Chu Etc.

6 August 2008 Different Protection Levels Between 20MHz Protection and Non-HT Protection If 20MHz protection can use EIFS, non-HT protection can also use EIFS. 11n does not need to invent new non-HT protection features. But actually 11n introduces new non-HT protection features. So 11n should provide stronger 20MHz protection. 40MHz AP1 AP1 40MHzData (STA1) 40MHzData (STA1) STA1 ACK ACK STA2 EIFS EIFS 40MHz STA1 20MHz STA2 Received corrupted frame HT-AP1 AP1 HT frame (STA1) HT frame (STA1) STA1 ACK ACK STA2 EIFS EIFS HT-STA1 Non-HT STA2 L. Chu Etc.

7 Proposed 20MHz Protection in 20/40MHz Infrastructure BSS
August 2008 Proposed 20MHz Protection in 20/40MHz Infrastructure BSS In a 20/40MHz infrastructure BSS, before transmitting a 40MHz HT frame, a STA or the AP shall first transmit a 20MHz HT frame in the primary channel. OR In a 20/40MHz infrastructure BSS, before transmitting a 40MHz HT frame, a STA or the AP shall first transmit a 40MHz non-HT duplicate frame. L. Chu Etc.

8 August 2008 Reference [1] /0746r2, “COEX LB ”, Matthew Fischer L. Chu Etc.


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