Define MIMO relative to $802\mathrm{.}11$n$.$

MIMO is a multiplexing technique in which the power is split into multipleparts called spatial currents.

MIMO is a frequency$-$division multiplexing technique in which the datastream is split into multiple parts called spectral streams.

MIMO is an OFDM multiplexing technique in which the digital data isportioned into multiple parts called filtered streams.

MIMO is a space$-$division multiplexing technique in which the datastream is split into multiple parts called spatial streams.