Interference alignment and power allocation for multi-user MIMO interference channels

We present centralized iterative algorithms that jointly determine the optimal transmit and receive filters as well as the optimal power allocation for a K-user multiple-input multiple-output (MIMO) interference channel (IC). The optimality criterion is based on the achievable sum-rate and the average per user multiplexing gain in the MIMO IC. By allowing channel state information (CSI) exchanged between users and a central unit (CU), we design a feedback topology where the CU collects local CSIs from all base stations (BSs), computes all transmit and receive filters and sends them to corresponding user-BS pairs. At the CU, we propose iterative algorithms utilizing alternating optimization strategy to design the filters. In most of the studies on the MIMO IC, choice of equal transmit powers for all user-BS pairs ignores the essential need to search for the optimal power allocation policy; they do not take the full advantage of the system's total power. How to allocate power among all the user-BS pairs in the network based on the sum-rate maximization strategy is the key to this paper. Thus, while the filters are designed at the CU, we propose a novel power allocation problem for sum-rate maximization under sum power constraint.