Regionalized Interference Alignment in Two-Tiered Cognitive Heterogeneous Networks

—Interference alignment in cognitive networks is an efficient way to achieve the cognitive system throughput gain without degrading the throughout of the primary system. In this paper a novel interference management strategy is presented to use interference alignment in cognitive heterogeneous networks flexibly. Characteristics of interference distribution in twotiered networks are considered to divide the cell deployed by this structure into two regions. Cognitive radio system determines which region the primary users locate in based on channel state information, and suppresses interference by designing their precoders to achieve interference alignment, hence is termed regionalized interference alignment. Thereby, it can manage interference in different situations effectively. Numerical results are given for the uplink average rates of primary user and second users, which shows that regionalized interference alignment ensures the performance of the cognitive heterogeneous networks.