MIMO uses multiple antennas at both the transmitter and receiver to improve wireless communication performance. It takes advantage of multipath propagation by using spatial diversity or spatial multiplexing. With spatial diversity, the same information is transmitted from different antennas to improve reliability and coverage. With spatial multiplexing, different data streams are transmitted from different antennas to increase data rates. MIMO can significantly increase capacity, quality, and spectral efficiency compared to single-input systems. It is used in technologies like 3G, 4G, and will be important for 5G networks.