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From: Richard Sharpe <>
	Ray Wang <rwang-+OaQ/>,
	"Aaron J. Lee"
	Tasheng Lin <tlin-+OaQ/>
Subject: Radiotap header for S1G captures and associated changes and other definitions
Date: Fri, 1 Mar 2019 17:59:58 -0800
Message-ID: <> (raw)

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Hi folks,

This is a second attempt at a RADIOTAP header for S1G captures.

Aaron Lee did the work in creating these definitions. I simply transcribed them.

The attached patch defines changes to the Channel field, 0-length-MPDU
field and a new S1G field.

There is also and associated definition for S1G NPD frames, which are
40-bit non-MAC frames transmitted by S1G STAs. I have included the
definition of those in this email, and they are essentially from
802.11ah-2016 with a little bit of helpful framing.

1. Channel field:

3 new values for Mask: 0x0002 for 700 MHz, 0x0004 for 800 MHz and
0x0008 for 900 MHz spectrum channels respectively.

2. 0-length MPDU field:

1 new value: 0x02 in the type value: 2 indicates that an S1G NDP
40-bit frame follows.

Note, this seems weird. Maybe the name of the field needs changing to
non-MAC frame or something.

3. The new S1G frame.

It consists of three 16-bit fields:

U16 known, U16 data1, U16 data2

0x0001 S1G PPDU format known
0x0002 Response indication known
0x0004 Guard Interval known
0x0008 NSS known
0x0010 Bandwidth known
0x0020 MCS Known
0x0040 Color known
0xFF80 Reserved

0x0003: S1G PPDU Format: 0=S1G_1M, 1=S1G_SHORT, 2=S1G_LONG
0x000C: Response indication: 0=NO_RESPONSE, 1=NDP_RESPONSE,
0x0010: Reserved
0x0020: Guard interval: 0=Long GI, 1=Short GI
0x00C0: Number spatial streams: 0=1 Spatial stream, 1=2, .. 3=4 Spatial streams
0x0F00: Bandwidth: 0=1MHz, 1=2MHz, 2=4MHz, 3=8MHz, 4=16MHz, 5-15 reserved
0xF000:  MCS (MCS rate index, 0-10, 11-15 reserved)

0x000F: Color: 0-7
0xFFF0: Reserved

The S1G NPD format is essentially from section 9.9 of 802.11ah-2016
with some additional syntactic sugar:

It is a 40-bit field.

The first 8 bits distinguishes between Management and Control frames
using the values 0x0F (management) and 0x20 (control).

The last two bits indicates the bandwidth, between 1MHz and 2MHz,

In between, a 1MHz NDP CMAC frame contains 26 used bits and 13 unused
bits. The used bits are defined in section 9.9 of 802.11ah-2016. A
1MHz NDP CMAC frame contains 37 used bits and one unused bit. Again,
the used bits are defined in 802.11ah-2016.

Richard Sharpe

[-- Attachment #2: 0001-Add-an-S1G-field-and-modify-the-0-length-PSDU-defini.patch --]
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             reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-02  1:59 Richard Sharpe [this message]
2019-03-05  3:18 Richard Sharpe
     [not found] ` <>
2019-03-05 11:58   ` Johannes Berg
     [not found]     ` <>
2019-03-05 15:29       ` Richard Sharpe
     [not found]         ` <>
2019-03-06  8:07           ` yodazhong-Re5JQEeQqe8AvxtiuMwx3w
2019-04-09  8:58   ` Johannes Berg

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