EHT PPDU Structure

IEEE^® 802.11™¹ is a packet-based protocol. Each packet, also called a physical layer protocol data unit (PPDU), contains preamble and data fields. The preamble fields contain the transmission vector format information. The data field contains the user payload and higher layer headers, such as medium access control (MAC) fields and cyclic redundancy check (CRC). The transmission vector format and the PPDU structure vary between 802.11 versions. The transmission vector (TXVECTOR) format parameter is classified as:

EHT to specify an extremely high-throughput (EHT) physical layer (PHY) implementation.
- EHT refers to fields formatted for association with 802.11be™(Wi-Fi 7) data. Reference [1] defines and describes the EHT PHY layer and PPDU.
- For EHT, the TXVECTOR parameters, as defined in Table 36-1 of [1], determine the structure of PPDUs transmitted by an EHT station (STA).

The table shows 802.11 versions that WLAN Toolbox™ supports, along with the supported TXVECTOR options and associated modulation formats.

802.11 Version	Transmission Vector Format	Modulation Format	Bandwidth/MHz
802.11b™	non-HT	DSSS/CCK	11
802.11a™	non-HT	OFDM only	5, 10, 20
802.11j™	non-HT	OFDM only	10
802.11p™	non-HT	OFDM only	5, 10
802.11g™	non-HT	OFDM	20
802.11g™	non-HT	DSSS/CCK	11
802.11n™ (Wi-Fi 4)	HT_MF, Non-HT	OFDM only	20, 40
802.11ac™ (Wi-Fi 5)	VHT, HT_MF, Non-HT	OFDM only	20, 40, 80, 160
802.11ah™	S1G	OFDM only	1, 2, 4, 8, 16
802.11ad™	DMG	Single Carrier and OFDM	2640
802.11ax™ (Wi-Fi 6)	HE	OFDMA	20, 40, 80, 160
802.11ba™	WUR	MC-OOK	20, 40, 80
802.11be (Wi-Fi 7)	EHT	OFDMA	20, 40, 80, 160, 320

For EHT, there are two transmission modes: EHT multi-user (EHT MU) and EHT trigger-based (EHT TB). The wlanEHTMUConfig and wlanEHTTBConfig configuration objects enable you to create PPDUs and waveforms for both of them.

The field structure for EHT PPDUs consists of preamble and data portions. The legacy preamble fields (L-STF, L-LTF, and L-SIG) are present in EHT, WUR, HE, VHT, and non-HT PPDUs. The RL-SIG and PE fields are common to EHT and HE PPDUs. This table summarizes the structure of an EHT MU PPDU.

PPDU Field Abbreviation	Description	Duration (µs)
L-STF	Non-HT Short Training field	8
L-LTF	Non-HT Long Training field	8
L-SIG	Non-HT Signal field	4
RL-SIG	Repeated Non-HT Signal field	4
U-SIG	Universal Signal field	8
EHT-SIG	EHT Signal field	4
EHT-STF	EHT Short Training field	4
EHT-LTF	EHT Long Training field	Variable
EHT-Data	Data field carrying the PSDUs	Variable
PE	Packet Extension field	Variable

The structure of an EHT TB PPDU is the same, except that the EHT-SIG field is not present and the EHT-STF has double the duration. For more information, see Section 36.3.4 of [1].

References

[1] IEEE P802.11be/D4.0. “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Amendment 8: Enhancements for Extremely High Throughput (EHT).” Draft Standard for Information Technology — Telecommunications and Information Exchange between Systems — Local and Metropolitan Area Networks — Specific Requirements.