3x3 MIMO uses three antennas to establish up to three streams of data with the receiving device. Compared to ordinary single antenna (SISO) networks, 3x3 offers up to a 300% increase in throughput.

With three spatial streams established the data payload is divided across all three antennas and transmitted over the same frequency band. The use of three unique polarisations is rare. Most 3x3 radio systems use either VVV-Pol or VVH-Pol configurations. Antennas are however usually spatially distributed within the device to ensure adequate ECC and isolations.

3x3 MIMO is not commonly found in cellular mobile or microwave-based systems, instead generally only found in 802.11n and first generation 802.11ac Wave 1 WiFi access points. 3x3 became largely redundant with the quick transition from 2x2 to 4x4 MIMO.