In order to increase MAC layer efficiency, IEEE 802.11ax/WiFi6 introduces OFDMA to the WiFi MAC layer. At its core, OFDMA allows multiples STAs to communicate with the AP (or vice versa) at the same time at the same channel with the same antennas. The standard offers four types of OFDMA access as: 1. Downlink OFDMA, 2. Uplink OFDMA, 3. Cascaded OFDMA, and 4. Uplink OFDMA Random Access.