What is Spatial Multiplexing

The MIMO technology provides the system with the spatial multiplexing gain and spatial diversity gain.

In spatial multiplexing, multiple antennas are used on the received end and transmit end and multipath components in spatial communication is used, allowing signals to be transmitted over multiple data channels (MIMO sub-channels) in the same frequency band. This technology makes the channel capacity linearly increase with the growing number of antennas. This increase in channel capacity does not require additional bandwidth and does not consume additional transmit power. Therefore, spatial multiplexing is an efficient means to improve channel capacity and system capacity.

In spatial multiplexing, serial-to-parallel conversion is performed on the transmitted signal to produce several parallel signal flows, which are then transmitted using their respective antennas in the same frequency band simultaneously. Due to the use of multipath propagation, each transmit antenna produces a unique spatial signal for the receive end. After the receive end receives the mixed signals of data, it differentiates these parallel data flows based on the fading between different spatial channels. Spatial multiplexing requires the spacing between transmit and receive antennas to be greater than the distance, ensuring that each sub-channel of the receive end is an independently fading channel.

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