Distributed CSIT Does Not Reduce the Generalized DoF of the 2-User MISO Broadcast Channel

In this letter we analyze the high signal-to-noise ratio regime performance of the multi-transmitter MISO broadcast channel with so-called distributed channel state information at the transmitters (CSIT), i.e., where CSIT is made transmitter-dependent. Specifically, we show the unexpected result that it is possible to achieve the same generalized degrees-of-freedom independently of whether a channel link estimate is present at one transmitter (TX), at the other TX, or at both, and regardless of the channel pathloss topology, thanks to a novel transmission scheme. The proposed scheme involves as key ingredient a new precoding scheme coined sliced zero-forcing which efficiently adapts to any distributed CSIT setting.