Re: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

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Sorry, I mean HE PPDU scrambler…

BRs,

Xiaogang.

From: Chen, Xiaogang C <xiaogang.c.chen@xxxxxxxxx>
Sent: Monday, September 21, 2020 2:53 PM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Hi Lin,

Not sure if we are aligned. With the 11ax scrambler as in the example below, at transmitter side, do you think the service field after scrambling is “0000111” or “1111111”?

BRs,

Xiaogang.

From: Lin Yang <linyang@xxxxxxxxxxxxxxxx>
Sent: Monday, September 21, 2020 11:56 AM
To: Chen, Xiaogang C <xiaogang.c.chen@xxxxxxxxx>; STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: RE: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Hi Xiaogang,

Regardless if we should keep the initial state as the 1^st a few bits in the scrambling sequence. In the following plot in Chenchen’s PDT, the initial state is sent to both XOR scrambling and the shift register. Yes the first 7 bits (now is 11 bits) are skipped and replaced by the initial state bits but they will be re-generated after the 11bits initial state move into the shift register completely. So with the initial state upfront, the sequence does not change, the difference is the entire scrambling sequence starts from the last state of the sequence generated by the given initial state. Thanks, Lin

From: Chen, Xiaogang C <xiaogang.c.chen@xxxxxxxxx>
Sent: Monday, September 21, 2020 8:08 AM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: [EXT] Re: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Hi Chenchen

The current figure actually changed the scrambling sequence. It works but it’s a new way to descramble.

Take the follow note as an example, with the current figure the sequence will be “1111111(initial state) 0 11110010….” So the first 7 bits are skipped and replaced with all 1.

For Rx, since the sequence is repeated, receiver only need to find the 7 bits match the first 7bits of service field and continue roll the 127bits sequence. It doesn’t need to generate only the fly.

BRs,

Xiaogang.

From: liuchenchen <liuchenchen1@xxxxxxxxxx>
Sent: Friday, September 18, 2020 5:27 PM
To: Chen, Xiaogang C <xiaogang.c.chen@xxxxxxxxx>; STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: 答复: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Hi Xiaogang

I think you referring to only the scramble case. But to descramble, the initial state shall be estimated and the scrambler shall be initialized. The same scrambler is used to scramble transmit data and to descramble receive data. So it may be better to keep it there.

BRs

Chenchen Liu

发件人: Chen, Xiaogang C [mailto:xiaogang.c.chen@xxxxxxxxx]
发送时间: 2020年9月18日 23:55
收件人: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
主题: Re: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Hi Chenchen

I double checked with Youhan and the rule should be as in the new figure. i.e. we don’t need the initialization branch which is only for non-HT dup BW indication.

Also I checked I.1.5.2 Scrambling the BCC example in 11md draft. You can see the first 7 bits after scrambling is not “1011101” which is used to initialize the scrambler. If the initialization branch always exist, the first 7 bits after scrambling should be “1011101”.

BRs,

Xiaogang.

From: liuchenchen <liuchenchen1@xxxxxxxxxx>
Sent: Thursday, September 17, 2020 11:50 PM
To: Chen, Xiaogang C <xiaogang.c.chen@xxxxxxxxx>; STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: 答复: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Hi Xiaogang

Thanks for your comments. All your comments are accepted except the modification to the figure. The initialization is always needed I think. We can talk more on that if needed.

BRs

Chenchen Liu

发件人: Chen, Xiaogang C [mailto:xiaogang.c.chen@xxxxxxxxx]
发送时间: 2020年9月18日 2:51
收件人: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
主题: Re: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Hi Chenchen,

I added more comments on top of Lin’s. Thanks.

BRs,

Xiaogang.

From: Lin Yang <linyang@xxxxxxxxxxxxxxxx>
Sent: Wednesday, September 16, 2020 9:40 PM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Thanks Chenchen for drafting the scrambler section. Please find my comments in the attached file.

Thanks,

Lin

From: liuchenchen <liuchenchen1@xxxxxxxxxx>
Sent: Wednesday, September 16, 2020 8:13 PM
To: STDS-802-11-TGBE@xxxxxxxxxxxxxxxxx
Subject: [EXT] [STDS-802-11-TGBE] PDT of scrambler and LTF sequence Uploaded

Dear TTT members and all.

The PDT draft on EHT PHY data scrambler and EHT LTF sequences has been uploaded. Please check it out and share your comments so as to make it better.

https://mentor.ieee.org/802.11/dcn/20/11-20-1495-00-00be-pdt-of-eht-ltf-sequences.docx

https://mentor.ieee.org/802.11/dcn/20/11-20-1494-00-00be-pdt-of-eht-phy-data-scrambler-and-descrambler.docx

Thank you

Best regards

Chenchen

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