Four new PPDU frame types in the 802.11ax physical layer
HE SU PPDU
single-user PPDU is mainly used in single-user scenarios.
HE ER SU PPDU
HE extended range (Extended Range) PPDU is mainly aimed at single-user scenarios far away from APs, such as outdoor scenarios. Due to the long distance and weak signal, HE_EXT_SU can only use low bandwidth for low-speed transmission to ensure transmission reliability.
HE MU PPDU
multi-user PPDU, can transmit one or more users to one or more users at the same time.
HE TB PPDU
HE trigger response frame (HE Trigger-Based PPDU), a single transmission, mainly to respond to the trigger frame. This frame format is mainly transmitted in uplink OFDMA or uplink MU-MIMO scenarios. This is because generally speaking, the MU uplink has strict requirements on the transmission power and transmission capabilities of the device (EVM, MCS support at the sender, spatial stream support, etc.). However, 802.11 has relatively broad requirements for terminal capabilities, with various high There is a big difference between low-end devices. In order to be compatible with high-end and low-end devices, devices that support the HE_Trig format need to be able to use this message to indicate whether they are high-end devices that can meet high requirements (Class A devices) or cannot meet the requirements Low-end equipment (Class B device).
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