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Radiotap

Introduction | defined fields | suggested fields | rejected fields

HE

Bit Number
23 (tentatively assigned, field data may change)

Structure

Required Alignment
2
Unit(s)
none

The presence of this field indicates that the frame was received or transmitted using the HE PHY.

This field contains data mostly from the HE-SIG-A part that is common to all HE transmissions, but some of the data might also be calculated (e.g. when included in the transmission of an HE_TRIG type frame, some parameters are not included in the HE-SIG-A but were determined by the trigger frame).

However, for PPDUs of HE_MU format, it contains the data that applies to the encoding of the PSDU, with more detailed information about the MU transmission contained in the HE-MU field if needed, in many cases that field will not be needed as all the data about the single user that was captured is already encoded here.

In the case of MU transmissions, the HE-MU-other-user field may also be present one or more times in that case to capture extra users for which the data couldn’t be captured; if the data was captured for more than one user then multiple packets must be written into the radiotap capture.

data1

0x0003 HE PPDU Format: 0=HE_SU, 1=HE_EXT_SU, 2=HE_MU, 3=HE_TRIG
0x0004 BSS Color known
0x0008 Beam Change known
0x0010 UL/DL known
0x0020 data MCS known
0x0040 data DCM known
0x0080 Coding known
0x0100 LDPC extra symbol segment known
0x0200 STBC known
0x0400 Spatial Reuse known (Spatial Reuse 1 for HE_TRIG format)
0x0800 Spatial Reuse 2 known (HE_TRIG format), STA-ID known (HE_MU format)
0x1000 Spatial Reuse 3 known (HE_TRIG format)
0x2000 Spatial Reuse 4 known (HE_TRIG format)
0x4000 data BW/RU allocation known
0x8000 Doppler known

data2

0x0001 pri/sec 80 MHz known
0x0002 GI known
0x0004 number of LTF symbols known
0x0008 Pre-FEC Padding Factor known
0x0010 TxBF known
0x0020 PE Disambiguity known
0x0040 TXOP known
0x0080 midamble periodicity known
0x3f00 RU allocation offset
0x4000 RU allocation offset known
0x8000 pri/sec 80 MHz (primary=0, secondary=1)

RU allocation offset

The RU allocation offset is encoded as the offset (within the 80 MHz pri/sec channel) of the location in the correct tone column.

26-tone 52-tone 106-tone 242-tone 484-tone 996-tone 2x996-tone
0 0 0 0 0 0 0
1
2 1
3
4
5 2 1
6
7 3
8
9 4 2 1
10
11 5
12
13
14 6 3
15
16 7
17
18
19 8 4 2 1
20
21 9
22
23
24 10 5
25
26 11
27
28 12 6 3
29
30 13
31
32
33 14 7
34
35 15
36

Note that while this table lists all possible positions, it doesn’t list all possible combinations, i.e. with an HE-MU transmission the RU allocation may be mixed into different bandwidths for different users.

data3

0x003f BSS Color
0x0040 Beam Change
0x0080 UL/DL
0x0f00 data MCS (not SIG-B MCS from HE-SIG-A for HE_MU format)
0x1000 data DCM (cf. data MCS)
0x2000 Coding (0=BCC, 1=LDPC)
0x4000 LDPC extra symbol segment
0x8000 STBC

data4

bits HE_SU and HE_EXT_SU format PPDU
0x000f Spatial Reuse
0xfff0 (reserved)
bits HE_TRIG format PPDU
0x000f Spatial Reuse 1
0x00f0 Spatial Reuse 2
0x0f00 Spatial Reuse 3
0xf000 Spatial Reuse 4
bits HE_MU format PPDU
0x000f Spatial Reuse
0x7ff0 STA-ID of the user for which the data was captured
0x8000 (reserved)

data5

0x000f data Bandwidth/RU allocation (0=20, 1=40, 2=80, 3=160/80+80, 4=26-tone RU, 5=52-tone RU, 6=106-tone RU, 7=242-tone RU, 8=484-tone RU, 9=996-tone RU, 10=2x996-tone RU)
0x0030 GI (0=0.8us, 1=1.6us, 2=3.2us, 3=reserved)
0x00c0 LTF symbol size (0=unknown, 1=1x, 2=2x, 3=4x)
0x0700 number of LTF symbols (0=1x, 1=2x, 2=4x, 3=6x, 4=8x, 5-7=reserved)
0x0800 (reserved)
0x3000 Pre-FEC Padding Factor
0x4000 TxBF
0x8000 PE Disambiguity

data 6

0x000f NSTS (actual number of space-time streams, 0=unknown, 1=1, etc.)
0x0010 Doppler value
0x00e0 (reserved)
0x7f00 TXOP value
0x8000 midamble periodicity (0=10, 1=20)