Hi folks,

Here is an updated proposal for this header.

It has undergone some modifications.

I include the patch to the radiotap git repo as well as a small C
program for generating such headers.

I have moved to using TLVs and have integrated Johannes' code for
handling Radiotap RLVs into Wireshark 2.6.2 and used my test program
to test the code.

The test code only generates three frames so far, but it could be
modified to provide broarder coverage.

I suggest that people making Radiotap proposals in the future should
also include code for generating such headers as it is pretty easy to
do so and makes it easier for people writing parsers.

We want to move forward with this and I have code now that dissects it
in Wireshark. Of course, that code is easy to change as well.

Here are the changes for the Channel field. Add three seemingly unused values:

| 0x0002 | S1G 700MHz spectrum channel |
| 0x0004 | S1G 800MHz spectrum channel |
| 0x0008 | S1G 900MHz spectrum channel |

Here is the new S1G field. It uses TLV Type value 32.

Note, we have also explicitly decided to place the Null Data Packet
(NDP) info into the S1G header. This reduces the amount of change
needed in dissectors but it does mean that the zero_length_ppdu
infrastructure that is already in Wireshark for example.

TLV Type Number
: 32

Structure
: u16 known, u16 data1, u16 data2, u8 ndp_type, u8[5] ndp_data;

Required Alignment
: 4

Unit(s)
: none

The presence of this field indicates the frame was capture using an S1G phy.

This field contains data to allow correct handling by programs like
Wireshark etc.

Is NDP indicates that this is an NDP frame, however, the content might
not be known.

## 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 |
| **`0x0080`** | Is NDP, which means no packet data follows this header! |
| **`0x0100`** | NDP content known |
| **`0xFE00`** | 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 |
| **`0x0700`** | Bandwidth: 0=1MHz, 1=2MHz, 2=4MHz, 3=8MHz, 4=16MHz,
5-15 reserved |
| **`0x0800`** | Reserved |
| **`0xF000`** | MCS (MCS rate index, 0-10, 11-15 reserved) |

## data2

| **`0x0007`** | Color: 0-7 |
| **`0xFFF8`** | Reserved |

## ndp_type

This value is only defined if ndp_known is true.

| **ndp_type value** | **Meaning** |
| 0x00 | NDP Control frame |
| 0x01 | NDP Management Frame |
| 0x02-0xFF | Reserved |

## ndp_data

This value is only defined if ndp_known is true. The bytes are as
defined in IEEE802.11ah, Section 9.9, except that ndp_data[4] is
defined as:

| **`0x3F`** | used and unused bits depending on the BW field and type |
| **`0xC0`** | Bandwidth: 0 = 1Mhz, 1 = 2MHz, 2-3 Reserved |

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