Multi-user transmission with downlink and uplink OFDMA - OFDMA increases user data rates and also reduces latency, especially for large numbers of devices with short frames or low data-rate requirements, such as voice and IoT devices. By providing multi-user capabilities, a channel can be divided in the frequency domain, and multiple transmissions can be carried simultaneously. OFDMA is particularly effective in raising network efficiency and capacity where there are many devices, short frames, or low data-rate streams.
Multi user transmission with downlink multi-user MIMO - MU-MIMO is another multi-user capability, originally introduced in 802.11ac. This improves network capacity by allowing multiple devices to transmit simultaneously.
Energy efficiency - As higher performance 802.11ax access points will handle a greater number of devices and traffic, they will be driving the need for more power consumption.