Question: how ofdm is used in wifi?
Answer: OFDM takes an RF channel, such as the 20 MHz channel often used in Wi-Fi, and instead of using a single carrier-frequency modulated by AM, FM, or other means, sets out a number of sub-carriers. 802.11ac used 52 data-carrying sub-carriers in a 20 MHz RF channel, while 802.11ax has 234.