Ergodic interference alignment for MIMO interference system with variable channel

The authors pay focus on the K user multiple-input multiple-output (MIMO) Gaussian interference channel (IC) with M transmitting antennas and N receiving antennas, in which min (M, N)/max (M, N) ⩾ (K−1)/[K (K−2)] and K > 3. The channel coefficients are variable, time varying or frequency selectively drawn from a continuous distribution. Based on ergodic interference alignment (IA), an achievable scheme was proposed to achieve a total of KMN/(M + N) degrees of freedom (DoF). The ergodic IA scheme can reach the optimal DoF value with simply linear beamforming and finite symbols. Furthermore, the achievable rate of the ergodic IA scheme was derived at any signal-to-noise ratio (SNR). With numerical simulation, the performance of the proposed scheme is evaluated.