We consider a two-tier cellular system where there is a macrocell base station equipped with multiple antennas transmitting to multiple microcells, each equipped with a microcell base station (relay) equipped with one antenna. Each microcell has one user. We explore the degrees of freedom (DoF) of several configurations of this network with the assumption that no channel state information (CSI) of the users is available at the macrocell base station and different assumptions on the CSI between other transmitter-receiver pairs. With very limited CSI and the relays, the achievable DoF can be greatly increased compared to the case when there is no relays.
