On the Degrees of Freedom Regions of Two-User MIMO Z and Full Interference Channels with Reconfigurable Antennas

TL;DR

This paper characterizes the degrees of freedom regions for two-user MIMO Z and full interference channels, introducing antenna mode switching to achieve optimal DoF and resolving a previously unknown special case.

Contribution

It derives the DoF region for the Z interference channel with CSIT and shows equivalence with the full interference channel in a specific antenna configuration, using antenna mode switching.

Findings

DoF region for Z interference channel with CSIT derived.

Equivalence of DoF regions for Z and full interference channels in a special case.

Systematic construction of DoF-achieving nulling and beamforming matrices.

Abstract

We study the degrees of freedom (DoF) regions of two-user multiple-input multiple-output (MIMO) Z and full interference channels in this paper. We assume that the receivers always have perfect channel state information. We derive the DoF region of Z interference channel with channel state information at transmitter (CSIT). For full interference channel without CSIT, the DoF region has been obtained in previous work except for a special case M1< N1<min(M2,N2), where M_i and N_i are the number of transmit and receive antennas of user i, respectively. We show that for this case the DoF regions of the Z and full interference channels are the same. We establish the achievability based on the assumption of transmitter antenna mode switching. A systematic way of constructing the DoF-achieving nulling and beamforming matrices is presented in this paper.