Orthogonal frequency-division multiplexing (OFDM) is a technique used for which types of amateur communication?

Explication

OFDM spreads a data stream across many closely spaced subcarriers, and amateurs use it in digital modes that need higher throughput or resistance to multipath, such as wideband HF data and mesh networking equipment. Nothing in the rules prohibits it, and it is not tied to very low power work or to moonbounce.