Topological interference management with transmitter cooperation

Interference networks with no channel state information at the transmitter (CSIT) except for the knowledge of the connectivity graph have been recently studied under the topological interference management (TIM) framework. In this paper, we consider a similar topological knowledge but in a distributed broadcast channel setting, i.e. a network where transmitter cooperation is enabled. We show that the interference topology can also be exploited in this case to strictly improve the degrees of freedom (DoF) as long as the network is not fully connected, which is a reasonable assumption in practice. A fractional graph coloring based interference avoidance and a subspace interference alignment approaches are proposed to characterize the symmetric DoF for so-called regular networks with constant interfering degree, and to identify achievable DoF for arbitrary network topologies.