Zero-forcing Beamforming (ZF-BF) is a spatial signal processing applied in multiple antenna wireless devices. For downlink, ZF-BF allows transmitters to send data to the desired users with nulling out the directions to the undesired users and for uplink, ZF-BF allows receivers get the signal from the desired users with restricting out the signals from the directions of the interference users.
Notice that the concept of the interference users in the receive mode is information theoretically dual to the undesired users in the transmit mode.
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