MIMO

Parts of this article (those related to 5G) need to be updated. Please help update this article to reflect recent events or newly available information. (February 2019)

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In radio, multiple-input and multiple-output (MIMO) (/ˈmaɪmoʊ, ˈmiːmoʊ/) is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation.^[1][2] MIMO has become an essential element of wireless communication standards including IEEE 802.11n (Wi-Fi 4), IEEE 802.11ac (Wi-Fi 5), HSPA+ (3G), WiMAX, and Long Term Evolution (LTE). More recently, MIMO has been applied to power-line communication for three-wire installations as part of the ITU G.hn standard and of the HomePlug AV2 specification.^[3][4]

At one time, in wireless the term "MIMO" referred to the use of multiple antennas at the transmitter and the receiver. In modern usage, "MIMO" specifically refers to a class of techniques for sending and receiving more than one data signal simultaneously over the same radio channel by exploiting the difference in signal propagation between different antennas (e.g. due to multipath propagation). Additionally, modern MIMO usage often refers to multiple data signals sent to different receivers (with one or more receive antennas) though this is more accurately termed multi-user multiple-input single-output (MU-MISO).