HT-LTF

PHY variable HT mixed-format PPDU unverified

Long training symbols, one per space-time stream, four microseconds each.

Reading a capture

The first place a preamble grows with antenna count. A four-stream transmission spends sixteen microseconds here where a one-stream frame spends four — a cost paid per transmission, not per octet.

Where it sits

HT mixed-format PPDU > HT-LTF

Accuracy

Clause
802.11-2024 §19.3.9.4.5
Verified
Not verified against the standard. Treat this as a claim, not a fact.