Low-complexity zero-forcing coordinated beamforming by adaptive-perturbation for multi-cell MIMO networks

In this paper, an adaptive coordinated zero-forcing beamforming scheme based on null space perturbation is proposed for eliminating the inter-cell interference in multi-cell MIMO networks. The scheme makes use of the time-correlation of the channel response to reduce the number of times of singular-value-decomposition of channel matrix for zero-forcing coordinated beamforming. We also analyze the specific rate loss resulting from null space perturbation theoretically and present the method to set up the perturbation step length of different base stations according to the interference strength of a specific user. The simulation results show that the proposed algorithm can effectively reduce the algorithm complexity and obtain a significant performance enhancement compared to the algorithm with fixed perturbation step length.