Orthogonal Frequency Division Multiple Access (OFDMA), introduced in 802.11ax, enhances efficiency by dividing a channel into smaller sub-channels called Resource Units (RUs). This allows multiple devices to transmit simultaneously within the same channel bandwidth, reducing latency and improving throughput. Unlike previous standards like 802.11n and 802.11ac, which primarily support single-user transmissions per channel, OFDMA's ability to handle multiple concurrent transmissions without relying on MU-MIMO leads to more efficient spectrum utilization and better performance in dense environments.