Accurate estimationand real-time compensation for phase offset and Doppler shift are essential for coherent multiinput multi-output (MIMO) systems.Here,a spatial multiplexing MIMO scheme with non-coherent frequency-shift keying (FSK) detection is proposed.It is immune to random phase interference and Doppler shift while increasing capacity.It is valuable that the proposed spatial multiplexing MIMO based on energy detection (ED) is equivalent to a linear system,and there is no mutual interference caused by the product of simultaneous signals in square-law processing.The equivalent MIMO channel model is derived as a real matrix,which remains maximal multiplexing capacity and reduces the channel estimation complexity.Simulation results show that the proposed scheme has outstanding performance over Rician flat fading channel,and experimental system obtains four times the capacity through 4 antennas on both transmitter and receiver.