Wi-Fi 7 MCS Table

A few years ago, I wrote a blog post titled “MCS Table Updated with 802.11ax Data Rates” which can be found here: link.

The blog post discusses the new sets of data rates that became available with 802.11ax (Wi-Fi 6) and explains how these Wi-Fi data rates are calculated. Feel free to take a look at it to learn more about this topic.

In this post, we will update the sets of Wi-Fi data rates to include the new data rates provided by the new 802.11be (Wi-Fi 7) standard.

COMPLETE MCS TABLE

The following table includes all the MCSs data rates (up to 8 spatial streams) defined by the 802.11n (HT), 802.11ac (VHT), 802.11ax (HE) and 802.11be (EHT) amendments:

Here is a link to the full MCS Table: ​https://mcsindex.net/

As you can see, the table is becoming quite large. In fact, 802.11be supports a total of 10,800 data rates. However, it’s important to note that not all of these data rates will be used in real-world scenarios.

REAL WORLD MCS TABLE

In order to focus on what will be most useful to Wi-Fi Engineers, I have created a smaller table which only focuses on sections of the complete table. I believe that this real world table will contain all of the Wi-Fi data rates we will use in enterprise networks:

Here is a link to the full MCS Table: ​https://mcsindex.net/

In the picture above, it is very clear that most of the new data rates introduced by 802.11be will be because of 2 new settings:

  • The use of a 320 MHz wide channel
  • The use of 4096-QAM

THE MATH BEHIND IT

The new 802.11be standards introduced a few new PHY techniques that will impact data rates:

  • New channel widths (320 MHz and MRUs)
  • New modulation technique (4K-QAM)
  • New set of supported spatial streams (up t0 16)
  • New transmission techniques (DCM and EHT-DUP)

The following section presents the updated information that is used to calculate 802.11be data rate.

As a reminder, here is the formula used to calculate Wi-Fi data rates with 802.11ax (Wi-Fi 6):

Good news, the formula stays the same for 802.11be (Wi-Fi 7).

Let’s now details each of these variables and which values they can have when EHT (802.11be) is used. The following table details the parameters used by HE:

Due to the addition of a new modulation technique (4096-QAM), 2 new MCS indexes are now available with 802.11be:

  • Index 12: when the 4096-QAM modulation is used with a coding of 3/4
  • Index 13: when the 4096-QAM modulation is used with a coding of 5/6

When 1 spatial stream is used, and due to the addition of 2 new transmission techniques (DCM and EHT-DUP), 2 additional new MCS indexes are available for 802.11be (when 1 spatial stream is used):

  • Index 14: when EHT-DUP mode is used
  • Index 15: when DCM is used

EXAMPLE

So now that we have this information, let’s try to understand the data rate that a typical Wi-Fi 7 device could use.

Let’s assume the following:

  • We are using a Wi-Fi 7 phone that supports up to 2 spatial streams
  • We are using a Wi-Fi 7 AP that supports up to 4 spatial streams
  • We configured the AP to use a 160 MHz wide channel on 6 GHz
  • We will assume that the phone will connect to the AP on 6 GHz

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 160MHz wide channel: 1960
  • Number of Coded bit per subcarrier (Modulation): we don’t know yet
  • Coding: we don’t know ye
  • Number of Spatial Streams: 2
  • OFDM Symbol Duration: 12.8µs
  • Guard Interval: we don’t know yet

So here is the list of possible data rates used by this device when connecting to this AP:

The phone was able to connect with a data rate of 2,882.4 Mbps. Therefore, we can now determine that:

  • MCS 13 was used
  • 4096-QAM with a coding of 5/6 was being used
  • A guard interval of 0.8µs was used

RESOURCES

Here are some resources that I have used or that can be interesting if you want to learn more about:

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butcher

I do not see hte minimum SNR required for each modulation. Is there a way to calculate it?

argon

Using the equation, Nsd = 1960, Nss = 2, Coding Rate = 1/2, BPSPCS = 1 for BPSK12, I get 13055041.18 Mbps for 0.8 us GI and 12.6 us OFDM symbol rate. In the table it says 144.1 Mbps. What did I miss?