Design and operation of Blind Interference Alignment in cellular and cluster-based systems

We consider the use of Blind Interference Alignment (BIA) in a cellular environment as a means for supporting downlink Multi-User MIMO (MU-MIMO) transmission without the need for channel state information at the transmitter (CSIT). This “CSIT-blind” characteristic of BIA is of particular interest for Frequency Division Duplex (FDD) systems, since it allows one to eliminate overheads and impairments due to downlink pilot training and CSIT quantization and feedback. As we demonstrate, when properly applied over cellular, BIA can enable control of both intra-cell and inter-cell interference. In this context, we explore the aspects of power-allocation, frequency reuse, and alignment-code reuse and their effect on cellular performance. BIA can also be jointly applied over clusters of cells. Cluster operation leads to lower inter-cell interference levels and potentially improved BIA system performance. BIA however, has some interesting operational aspects when used with clusters. These include some benefits over CSIT-based MU-MIMO since individual cells do not need to share channel knowledge and can transmit independent information streams, some challenges in more complex receiver hardware, and relationships to cellular with code-reuse. We discuss such aspects and investigate the application of BIA in both cellular and cluster deployments.