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

Known:
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

Data1:
0x0003: S1G PPDU Format: 0=S1G_1M, 1=S1G_SHORT, 2=S1G_LONG
0x000C: Response indication: 0=NO_RESPONSE, 1=NDP_RESPONSE,
2=NORMAL_RESPONSE, 3=LONG_RESPPNSE
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)

Data2:
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.

-- 
Regards,
Richard Sharpe
(何以解憂？唯有杜康。--曹操)(传说杜康是酒的发明者)