OFDMA:
The 802.11ax standard introduces Orthogonal Frequency-Division Multiple Access (OFDMA) technology to Wi-Fi for the first time. Used for some time in cellular phone systems, OFDMA divides each WLAN sub-channel into multiple subsets so that the available bandwidth can be allocated to more users. Each station using the Wi-Fi system occupies one or more portions of a channel, depending on the bandwidth required. Access Point (AP) scheduling allows multiple stations to receive and send packets at the same time, thereby reducing contention and backoff between stations, lowering network latency, and improving network efficiency.
8 x 8 UL/DL MU-MIMO:
The 802.11ax standard extends Multi-User, Multiple Input, Multiple Output (MU-MIMO) technology from 4 x 4 (four antennas and radios) in 802.11ac Wave 2 to 8 x 8. The 802.11ax standard introduces uplink MU-MIMO technology to communicate with more stations simultaneously, thereby improving the system capacity and overall data rate.
1,024-QAM
802.11ax introduces the higher-order modulation and coding scheme 1,024-QAM. Quadrature Amplitude Modulation (QAM) combines signal phase and amplitude variations to encode bits into “symbols” for transmission. The higher the number in the name of the modulation scheme, the more finely the technology is dividing the available radio spectrum. Thus, 1,024-QAM achieves 25 percent higher transmission efficiency compared to the 256-QAM used in Wi-Fi 5 (802.11ac).
BSS-Color Spatial Reuse Technique
Wi-Fi 6 enables a spatial reuse technique to improve system performance
and spectrum resource utilization in dense deployment environments.
Based on a Basic Service Set (BSS) coloring mechanism, an 802.11ax AP
can identify overlapping BSSs from adjacent APs and dynamically adjust
the Clear Channel Assessment (CCA) threshold as well as transmit power
to avoid interference. This ongoing adjustment capability allows
multiple APs to cover an area with minimal contention, so that the whole
Wi-Fi 6 setup can implement channel spatial reuse to improve system
performance and capacity.
