  In recent years, there has been extensive research on millimeter-wave
(mmWave) communication and on in-band full-duplex (FD) communication, but work
on the combination of the two is relatively lacking. FD mmWave systems could
offer increased spectral efficiency and decreased latency while also suggesting
the redesign of existing mmWave applications. While FD technology has been
well-explored for sub-6 GHz systems, the developed methods do not translate
well to mmWave. This turns us to a method called beamforming cancellation
(BFC), where the highly directional mmWave beams are steered to mitigate
self-interference (SI) and enable simultaneous transmission and reception
in-band. In this paper, we present BFC designs for two fully-connected hybrid
beamforming scenarios, both of which sufficiently suppress the SI such that the
sum spectral efficiency approaches that of a SI-free FD system. A simulation
and its results are then used to verify our designs.
