HT mixed-format PPDU PPDU

A high-throughput transmission that a legacy station can still recognise and defer to.

Reading a capture

The compatibility is not free — the legacy preamble is 20 microseconds that an HT receiver does not need and cannot use for HT decoding. Every later PHY pays the same tax for the same reason.

Subfields

• HT-SIG — Two OFDM symbols carrying everything needed to decode the HT portion.
• HT-STF — Short training for the HT portion, resetting gain control after the signalling fields.
• HT-LTF — Long training symbols, one per space-time stream, four microseconds each.
• Data field — The HT data field, carrying the PSDU.

Where it sits

HT mixed-format 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 §19.3.2

Verified

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