With the new modulation scheme of 1024QAM (10bit), MCS9 and MCS10 are introduced in 11ax. [Introduction of 1024QAM] The change in OFDM does not bring much difference in Data rate between 11ac and 11ax, when the same MCS is applied. [Comparison on MCS9 between 11ac and 11ax] The highest data rate (MCS11) with 80MHz bandwidth (1SS) of 11ax is about 600Mbps, while 11ac has 433.3Mbps. [Comparison on highest data rate between 11ac and 11ax]

You can find data rate number of SU and RU for each MCS in the table below. [Data rate for HE20/40/80/160 of SU and full RU] [Data rate for 26, 52, 106 tone RU]

Introduction of 1024QAM

One subcarrier now carries up to 10 bit information in 11ax. With 1024 QAM, 11ax has higher data rate as MCS10 (1024QAM, 3/4 coding rate) and MCS11 (1024QAM, 5/6 coding rate). LDPC is mandatory and BCC cannot be used in MCS10 and MCS11 for coding scheme. For more about modulation, find Modulation & Constellation chapter.

1024QAM : New Modulation Scheme in HE, Wi-Fi, wifi, WLAN, IEEE802.11ax
1024QAM : New Modulation Scheme in HE
Comparison on MCS9 between 11ac and 11ax

Logically, with 4 more subcarriers in 4 times longer symbol, 11ax OFDM makes the same data rate of 11ac OFDM. With the same modulation and coding rate, and with the longest GI (Long GI for 11ac and 3.2usec GI for 11ax), VHT80 and HE80 data rate are 390Mbps and 408.33Mbps each. The reason they have a small amount of difference is the number of subcarrier utilized. 234 data subcarriers in 11ac and 980 data subcarriers in 11ax in case of 80MHz BW. 980 is slightly over 4 times of 234. (234 x 4 = 936 < 980)

For reference, the numbers of data subcarriers in HE20, 40 and 80 are 234, 468 and 980.

VHT and HE Data Rate Comparison : MCS9, Wi-Fi, wifi, WLAN, IEEE802.11ax
VHT and HE Data Rate Comparison : MCS9
Comparison on highest data rate between 11ac and 11ax

Along with Normal GI, 2 bit more information on each subcarrier and 4 times more subcarrier in one symbol in 11ax masks a big difference (about 30%) between 11ac and 11ax at highest data rate.

VHT and HE Data Rate Comparison : highest MCS, Wi-Fi, wifi, WLAN, IEEE802.11ax
VHT and HE Data Rate Comparison : highest MCS
Data rate for HE20/40/80/160 of SU and full RU
HE Data Rate for SU and full RU, Wi-Fi, wifi, WLAN, IEEE802.11ax
HE Data Rate for SU and full RU
Data rate for 26, 52, 106 tone RU
HE Data Rate for 26,52,106 tone RU
HE Data Rate for 26,52,106 tone RU
HE data rate with MIMO, DCM and GI

Data rate with DCM is half of data rate without DCM. With normal GI (0.8 usec), data rate goes up by 15% compared with Quadrature GI (3.2 usec)

HE Data Rate with MIMO, DCM and GI
HE Data Rate with MIMO, DCM and GI

End of Topic

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