HE MU PPDU format: It is used when transmitting to one or more users.HE extended range SU PPDU format: It is used when transmitting to a single user,īut further away from the Access Point (AP) such as in an outdoor scenario.HE SU PPDU format: It is used when transmitting to a single user.(PLCP) protocol data unit (PPDU) formats as described below. IEEE 802.11ax defines four different transmit modes i.e. packet extension modes of duration either 8 µs or 16 µs are used at the end of the 802.11ax frame. HE SIG-B is included only for multi-user packets. MCS rate, modulation, BSS color, BW, spatial stream, remaining time in transmit opportunity etc. HE SIG-A contains information about packet to follow both in downlink and uplink, ➨The HE header usually consists of HE SIG-A and HE SIG-B fields. ➨HE preamble contains HE-STF and HE-LTF patterns. The HE preamble can be decoded by 802.11ax devices only. RL-SIG field is used as repeated legacy (non-HT) Signal field. It is included for backward compatibility and coexistence with the legacy wifi devices. This legacy part is decoded by legacy devices. non-HT short training field), L-LTF (legacy long training field) and L-SIG (legacy signal field). The legacy portion of the preambleĬontains L-STF (Legacy i.e. The first part of the preamble consists of legacy (non-HE) training fields,Īnd second part consists of HE preamble fields. Let us understand various WLAN 802.11ax frame fields. The figure-1 depicts both single user and multi user frame structures. It consists of preamble, header and data. Its structure is similar to 802.11n and 802.11ac. Higher modulation schemes such as 1024-QAM have been introduced to improve throughput. MU-OFDMA for high efficiency (HE), 8x8 MU-MIMO for high capacity andĬontentionless uplink scheduling for power savings, BSS coloring to avoid CCI and so on. Moreover many new features have been introduced in this WLAN standard Unlike 802.11ac, 802.11ax operates in both 2.4GHz and 5GHz bands. The 11ax devices are backward compatible with legacy wifi devices as perġ1a/g/n/ac standards operating in the same band. preamble,header and data.Ĩ02.11ax standard is latest in the series of IEEE 802.11 WLAN standards. This 11ax frame structure consists of various fields viz. This page describes WLAN 802.11ax frame structure and PPDU formats as defined in IEEE 802.11ax standard. WLAN 802.11ax Frame Structure | 802.11ax PPDU formats
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