MIMO and beamforming

In short: MIMO uses several antennas to transmit more data in parallel, beamforming aims the signal at a particular device.

In more detail: Both are ways to get more out of the same radio channel without raising the frequency.

In Depth

• MIMO (“multiple input, multiple output”): Transmitter and receiver have several antennas. Reflections in the room, once a nuisance, are used to send several independent data streams (“spatial streams”) at once. “2x2” means two transmit and two receive antennas.
• MU-MIMO: The router serves several devices at once with their own streams instead of one after another. From Wi-Fi 5 (downlink), Wi-Fi 6 also uplink.
• Beamforming: The router sets the antenna phases so signals reinforce at the target device. Result: a steadier connection, longer reach at the same power.
• In practice: On the device side (phones) often only 1 to 2 antennas are fitted, which limits the gain.
• Also in mobile networks: 4G/5G use “massive MIMO” with dozens of antenna elements.
• Context: See Wi-Fi standards and modulation.

See also: 5G