Degrees of Freedom of Millimeter Wave Full-Duplex Systems With Partial CSIT

The degrees of freedom (DoF) of L-path poor scattering full-duplex (FD) systems is studied in which a FD base station having M transmit antennas and M receive antennas supports a set of half-duplex mobile stations (MSs). Assuming no self-interference, a hybrid scheduling is proposed achieving the optimal sum DoF with partial channel state information at the transmitter side as the number of MSs increases. In particular, the proposed scheme combines a zero-forcing beamforming for uplink and a random transmit beamforming for downlink with opportunistic scheduling. It is shown that the optimal sum DoF of 2M is asymptotically achievable as long as the number of MSs scales faster than snr^min(M-1,L)+M, where snr denotes the signal-to-noise ratio.