Interference Alignment With Finite Extensions in Partially Connected Networks.

In this paper, we investigate the interference alignment (IA) for a class of partially connected multi-input multi-output heterogeneous networks, which consist of $L$ fully connected pico cells, $J$ partially connected pico cells, and one macro cell. In particular, we investigate the feasibility of IA conditions with no channel extensions, $T$ -independent channel extensions, and $T$ -dependent channel extensions, respectively, for the single beam case. We present three theorems to characterize some necessary conditions, which $L$ , $J$ , $T$ , and the channel diversity order $\overline L$ must jointly satisfy when IA conditions are feasible. These necessary conditions also implicitly impose the constraints on the upper bounds of achievable degrees of freedom with different channel extensions. [ABSTRACT FROM PUBLISHER]