U-SIG

Type

33

Structure

• u32 common
• u32 value, mask

Required Alignment

4

Unit(s)

none

This field indicates the (known) contents of the U-SIG.

Note that the common/value/mask fields are ordered in this way so if they’re all known, the U-SIG bits are all contiguous in memory in the same way as over the air from bit 12 of the common field to the end of the value field.

common

Note: If the “bad U-SIG CRC” bit is set, the RX flags field should indicate PLCP CRC check failed as well, this bit just serves to differentiate where the CRC check failed.

value / mask

Contains a known mask and value for the remaining U-SIG bits that can only be interpreted depending on the PHY version.

The bits are in the on-air order, i.e. U-SIG-1 B20-25 followed by U-SIG-2 B0-25. Thus, U-SIG-1 B20-25 are in mask and value bits 0x0000003f.

Dissectors should show these per spec, in a PHY version specific namespace (e.g. “U-SIG::EHT::PPDU-Type-And-Compression-Mode”).

For the only currently defined version (PHY Version identifier 0 for EHT), the bits are shown in the following tables:

EHT MU PPDU U-SIG contents

An EHT PPDU is an EHT MU PPDU if

• the UL/DL field is set to 0 and the PPDU Type And Compression Mode field is set to 0, 1 or 2;
• the UL/DL field is set to 1 and the PPDU Type And Compression Mode field is set to 1.

EHT TB PPDU U-SIG contents

An EHT PPDU is a EHT TB PPDU if

• the UL/DL field is set to 1 and the PPDU Type And Compression Mode field is set to 0.