On degrees of freedom scaling in layered interference networks with delayed CSI

The multi-hop layered interference network is investigated with delayed knowledge of channel state information (CSI) at all nodes. It is demonstrated how multi-hopping can be utilized to increase the achievable degrees of freedom (DoF). In particular, for the K-user 2K-hop interference network, a multi-phase transmission scheme is proposed which systematically exploits the layered structure of the network and delayed CSI to achieve DoF values which scale with K. As such, this result provides the first example of a network with distributed transmitters and delayed CSI whose DoF scales with the number of users, although sub-linearly.