Cross-tier Interference Reduction in MIMO Heterogeneous Network with Imperfect CSI

The spectrum insufficiency has become a major problem in wireless communication systems due to increasing the demand on broadband applications. Heterogeneous macro-small cell network, Device-to-device (D2D) communications, and multiple-input multiple-output (MIMO) systems all are promising technologies to improve the spectrum efficiency and the data rate in future cellular networks. In this paper, the problem of cross-tier interference reduction in MIMO in heterogeneous macro-small cell network enabling D2D communications is investigated in presence of imperfect Channel State Information (CSI). Underlaying D2D communications, sharing the same resource of the cellular network, causes co-channel interference. Two precoding selection methods are used in the D2D underlaying MIMO system. The first one aims to maximize the rate of the D2D user while the second one aims to reduce the cross-tier interference between the D2D and the cellular user. Simulations are performed to investigate the effect of imperfect CSI on the system performance using the two selection methods.