Single-User vs. Multi-User MIMO: Key Differences

Let’s explore the difference between Single-User MIMO (SU-MIMO) and Multi-User MIMO (MU-MIMO). These technologies are used in wireless communication, particularly in Wi-Fi networks compliant with standards like IEEE 802.11ac.

Single-User MIMO

As shown in Figure 1, an access point (like a Wi-Fi router) compliant with the IEEE 802.11ac standard uses multiple antennas to transmit multiple data streams. The key thing here is that all of these streams are directed towards a single device. This is what defines Single-User MIMO. It’s essentially boosting the connection speed and reliability for one device at a time.

Multi-User MIMO (MU-MIMO)

Figure 2 illustrates Multi-User MIMO. Again, the access point uses multiple antennas to transmit multiple streams. However, unlike SU-MIMO, these streams are now directed to multiple devices simultaneously. As shown in the picture, two streams might be directed to a Nokia mobile phone, one stream to a tablet, and another to a laptop. This simultaneous transmission to multiple users is what defines MU-MIMO.

MU-MIMO is sometimes referred to as just “MU-MIMO”.

Because the receiving devices are often in close proximity, MU-MIMO systems rely on feedback from each individual device to optimize the transmission. This feedback helps the access point shape the radio signals to best reach each device without interference.