HE SU PPDU PPDU

A high-efficiency single-user transmission — legacy preamble, HE preamble, data, and a packet extension.

Reading a capture

Its preamble is roughly twice the length of a non-HT one. That is not a regression: the extra fields buy a far higher data rate and the ability to share the medium, and on a long frame the fixed cost is repaid many times over. On a short frame it is not, which is the whole argument for aggregation.

Subfields

• Repeated L-SIG — An exact repeat of the L-SIG symbol.
• HE-SIG-A — Two OFDM symbols carrying the parameters needed to decode the rest of the transmission.
• HE-STF — A short training field for the HE portion, used to reset automatic gain control after the signalling fields.
• HE-LTF — Long training symbols, one or more per spatial stream, used to estimate the channel for the HE data that follows.
• Data field — The HE data field, carrying the PSDU handed down by the MAC.
• Packet Extension — Extra time at the end of the transmission, giving the receiver room to finish processing.

Where it sits

HE SU PPDU

• Open in the explorer — Ack
• Open in the explorer — TCP over IPv4, in a protected QoS Data frame, aggregated
• Open in the explorer — Association Request
• Open in the explorer — Association Response
• Open in the explorer — Beacon
• Open in the explorer — Compressed Block Ack
• Open in the explorer — CTS
• Open in the explorer — Four-way handshake message 1
• Open in the explorer — Four-way handshake message 2
• Open in the explorer — Four-way handshake message 3
• Open in the explorer — Four-way handshake message 4
• Open in the explorer — Probe Request
• Open in the explorer — Probe Response
• Open in the explorer — ARP request in a QoS Data frame
• Open in the explorer — ICMP echo over IPv4, in a QoS Data frame
• Open in the explorer — UDP over IPv6, in a QoS Data frame
• Open in the explorer — TCP over IPv4, in a protected QoS Data frame
• Open in the explorer — TCP over IPv4, in an open QoS Data frame
• Open in the explorer — UDP over IPv4, in a QoS Data frame
• Open in the explorer — RTS
• Open in the explorer — Trigger frame

Accuracy

Clause

802.11-2024 §27.3.11

Verified

Not verified against the standard. Treat this as a claim, not a fact.