K-user symmetric MIMO distributed full-duplex network via wireless side-channels

We study the impact of leveraging out-of-band wireless side-channels between interfering transceiver pairs in a symmetric K-user cyclic MIMO interference channel, where each transmitter interferes with only one neighboring receiver in a cyclic manner. The focus of the paper is to characterize the symmetric capacity of such K-user side-channel assisted MIMO cyclic interference channel with M transmit antennas and N receive antennas. We show that a vector bin-and-cancel scheme achieves the symmetric capacity to within a constant gap irrespective of channel parameters. We give a complete characterization of the symmetric generalized degrees of freedom (GDoF) per user per antenna as a function of antenna number ratio max{M,N}/min{M,N} and side-channel bandwidth. The insights gained from the GDoF reveal the tradeoff between spatial resources from multiple antennas and spectral resources of the side-channels.