I recently purchased a Wi-Fi 6 device (Samsung Galaxy S10), and when I checked which date rate it was using over the Wi-Fi, this is what I got:
This blog presents the results of the new MCS table updated to include all the new 802.11ax data rates. It also presents how these data rates are calculated.
Complete MCS Table
The following table includes all the MCSs data rates defined by the 802.11n (HT), 802.11ac (VHT) and 802.11ax (HE) amendments:
As you can see, the table is getting very big. In fact, 802.11ax is introducing 2880 new data rates. However, not all data rates will be used in the real world. In order to focus on what will be most useful to Wi-Fi Engineers, I have created some smaller tables which only focuses on sections of the complete table.
MCS Table up to 3 Spatial Streams
This table presents 802.11n (HT), 802.11ac (VHT) and 802.11ax (HE) data rates for up to 3 spatial streams:
802.11ax MCS Table
This table only presents the data rates for 802.11ax communications up to 3 spatial streams:
802.11ax MCS Table (OFDM)
This table only presents the data rates for 802.11ax communications when OFDM is used:
802.11ax MCS Table (OFDMA)
This table only presents the data rates for 802.11ax communications when OFDMA is used:
The Math Behind It
Here is the formula we can use to calculate which data rate is used for both 802.11n and 802.11ac:
Let’s detail each of these variables and which value they can have for both 802.11n and 802.11ac:
HT and VHT OFDM Parameters
Here is the formula we can used when OFDMA is used (it is pretty much the same except that we define the number of data subcarriers per RU and not per channel):
Let’s now details each of these variables and which values they can have when HE (802.11ax) is used. The first table details the parameters used when OFDMA is not used. The second table details the parameters when OFDMA and resource units are used.
HE OFDM Parameters
HE OFDMA Parameters
So based on this information, we can determine some of the variables required to calculate the data rate and narrow down the data rates that will be used by this device:
Number of Data Subcarriers for an 80MHz wide channel: 980Number of Coded bit per subcarrier (Modulation): we don’t know yetCoding: we don’t know yetNumber of Spatial Streams: 2OFDM Symbol Duration: 12.8µsGuard Interval: we don’t know yetSo here is the list of possible data rates used by this device when connecting to this AP: