Distributed interference alignment and power allocation with QoS requirements

We study interference alignment (IA) with quality of service (QoS) requirements in a K-user multiple input multiple output interference channel (K-user MIMO IFC). Specifically, we establish design formulations: i) that maximize the minimum signal-to-interference-noise ratio (SINR) at receivers, and that ii) minimize the sum mean squared error (Sum-MSE). The uplink-downlink (UL-DL) SINR duality is firstly established for the K-user MIMO IFC. With this result, we develop iterative IA algorithms which design the transmit/receive filters and optimizes power allocation among users jointly. The convergence of the proposed algorithms is proved based on the established UL-DL SINR duality. Numerical results show that, compared with the classic distributed IA algorithm and Max-SINR algorithm, the proposed algorithms achieve significant gain under mild signal-to-noise ratios (SNRs), and exhibits similar performance at high SNRs.