Topological interference management for interference broadcast channels with alternating connectivity

Topological interference management is the study of achievable rates within communication networks with no channel state information at the transmitter (CSIT) beyond knowledge of the network structure itself. In this paper, we consider topological interference management within the context of a two-cell two-user-per-cell interference broadcast channel (IBC) with alternating connectivity. Topological feedback, even though minimal, allows the transmitters to track the changing network topology and then exploit the varying connectivity states to obtain a degrees of freedom (DoF) gain. We derive novel outer bounds on the DoF achievable by the two-cell two-user-per-cell IBC with alternating connectivity. The analysis initially focuses on the single-input single-output (SISO) case and is later extended to multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) systems. While global channel knowledge is restricted to topological information only, varying degrees of local CSIT availability are considered, depending on the network configuration. Additionally, we investigate the achievability of the derived bounds and for the case where all alternating connectivity states are equiprobable propose new transmission schemes based on joint coding across states.