Outer bounds of spatial degrees of freedom for MIMO interference channel without CSIT and with only local CSIT

This paper discusses characteristics of spatial degrees of freedom for K-user symmetric MIMO interference channel. We assume that the interference channel is equipped with Mt antennas at each transmitter and Nr antennas at each receiver and there is no channel extension over time and frequency. Two outer bounds are obtained for total spatial degrees of freedom of the interference channel with no channel state information(CSI) and only local CSI available at the transmitters respectively.