DMG 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:

DMG to specify a directional multi-gigabit (DMG) PHY implementation.
- DMG refers to preamble fields formatted for association with 802.11ad™ data. Section 20 of [1] defines and describes the DMG PHY layer and PPDU.
- For DMG, the TXVECTOR parameters, as defined in Table 20-1 of [1], determine the structure of PPDUs transmitted by a DMG station (STA). For a DMG STA, the MCS parameter determines the overall structure of the DMG PPDU.

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

DMG supports three PHY modulation schemes: control, single-carrier (SC), and orthogonal frequency division multiplexing (OFDM). The wlanDMGConfig object enables you to create PPDUs and waveforms for all of them.

The structures of the three kinds of DMG PPDU

The single-carrier chip timing, T_C = 1/F_C = 0.57 ns. For more information, see Waveform Sampling Rate.

The supported DMG format PPDU field structures each contain these fields:

The preamble contains a short training field (STF) and channel estimation field (CEF). The preamble is used for packet detection, automatic gain control (AGC), frequency offset estimation, synchronization, indication of modulation type (Control, SC, or OFDM), and channel estimation. The format of the preamble is common to the Control, SC, and OFDM PHY packets.
- The STF is composed of Golay Ga sequences as specified in Section 20.3.6.2 of [1].
- The CEF is composed of Golay Gu and Gv sequences as specified in Section 20.3.6.2 of [1].
  - When the header and data fields of the packet are modulated using a single carrier (control PHY and SC PHY), the Golay sequencing for the CEF waveform is shown in Figure 20-6 of [1].
  - When the header and data fields of the packet are modulated using OFDM (OFDM PHY), the Golay sequencing for the CEF waveform is shown in Figure 20-7 of [1].
The header field is decoded by the receiver to determine transmission parameters.
The data field is variable in length. It carries the user data payload.
The training fields (AGC and TRN-R/T subfields) are optional. They can be included to refine beamforming.

Section 20.3 of [1] specifies the common aspects of the DMG PPDU packet structure. The PHY modulation-specific aspects of the packet structure are specified in these sections:

The DMG control PHY packet structure is specified in Section 20.4.
The DMG OFDM PHY packet structure is specified in Section 20.5.
The DMG SC PHY packet structure is specified in Section 20.6.

References

[1] IEEE Std 802.11-2020 (Revision of IEEE Std 802.11-2016). “Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications.” IEEE Standard for Information Technology — Telecommunications and Information Exchange between Systems — Local and Metropolitan Area Networks — Specific Requirements.