MIMO (Multiple Input Multiple Output) is an antenna technology for wireless communication. In this technology, multiple antennas are used for the source (transmitter) and the destination (receiver). The antennas at each end of the communication loop are combined to achieve minimum error and optimal data transmission speed. MIMO is one of several forms of smart antenna technology, others are MISO (Multiple Input Single Output) and SIMO (Multiple Input Multiple Output).

In traditional wireless communication, the source uses one antenna and the destination uses another antenna. In some cases, this design leads to the problem of multipath effect. When the electromagnetic field encounters obstacles such as peaks, canyons, buildings and facilities, the wavefront is dispersed, so that the electromagnetic wave can reach its destination along multiple paths. The latecomers of the signal scattering part cause problems such as attenuation, pattern (steep wall effect) and intermittent reception (picket fence). In digital communication systems such as wireless Internet, it will slow down data transmission speed and increase errors. Using two or more antennas, combined with multi-channel signal transmission at source and destination (one antenna transmits one channel), the interference caused by multipath propagation is eliminated, and even this effect is utilized.

Because of its possible applications in digital television (DTV), wireless local area networks (WLANs), metropolitan area networks (man) and mobile phone communication, MIMO technology has attracted extensive attention.