Performance Optimization of MIMO Y Channels: Interference Alignment and Signal Detection

In this letter, we propose a combined scheme of interference alignment and signal detection to optimize the performance of a multiple-input multiple-output (MIMO) Y channel, which consists of three users and a middle relay equipped with n_U and n_R antennas, respectively. First, an iterative interference alignment algorithm is introduced to optimize both beamforming and combining vectors by minimizing the spillage of the interference signals, and ensuring that the desired signals fall into the orthogonal complement of the interference subspace. Then, a signal detection scheme, which employs feed-forward and feedback filters, is applied at the relay to further deal with system interferences. Simulation results show that the proposed combined scheme for MIMO Y channels produces a significant improvement over the existing schemes.