IEEE 802.11a introduced Wi-Fi operation in the 5 GHz band with orthogonal frequency-division multiplexing (OFDM) in 1999.
The standard offered theoretical data rates up to 54 megabits per second, a major improvement over the original 2 Mbps 802.11 standard. OFDM divided the radio signal across multiple closely spaced subcarriers, helping the system carry data efficiently in challenging wireless environments.
802.11a used the 5 GHz band, which generally had less interference than the crowded 2.4 GHz band used by early 802.11b devices. However, its higher frequency produced shorter range and weaker penetration through walls, so 802.11b became more common in early home networks.
The “a” in 802.11a is easy to confuse with the later 802.11g standard. 802.11g also supported speeds up to 54 Mbps but operated in the 2.4 GHz band and was designed for compatibility with 802.11b. Modern Wi-Fi standards retain OFDM-based techniques while using wider channels and multiple antennas.