MU-MIMO stands for multi-user, multiple input, multiple output, and represents a significant advance over single-user MIMO (SU-MIMO), which is generally referred to as MIMO. MIMO technology was created to help increase the number of simultaneous users a single access point can support. This was initially achieved by increasing the number of antennas on a wireless router.

MU-MIMO technology is now recognized as a major part of the Wi-Fi 6 (802.11ax) protocol, which emerged from the 802.11ac protocol. Standards older than 802.11ac (such as 802.11b, g and n) do not support MU-MIMO.

With MU-MIMO supported in 802.11ac (Wi-Fi 5), many endpoints and access points now come equipped with MU-MIMO technology. It’s still in the early days of Wi-Fi 6 and 6E (which extends the wireless spectrum available in the 6GHz band), but you can check with the Wi-Fi Alliance to see if a specific product includes MU-MIMO and Wi-Fi 6. Chip shortages and supply chain delays due to the pandemic slowed the adoption of Wi-Fi 6, but many are hopeful that the technology will take off in 2022.

With 802.11ax (Wi-Fi 6), basic MU-MIMO was updated to include uplink MU-MIMO, which means that an access point transmitting concurrently to multiple receivers can now also simultaneously receive from multiple transmitters (that also include uplink MU-MIMO). With 802.11ac (Wi-Fi 5), MU-MIMO was limited to downlink transmissions (from an access point to an endpoint).