Partial Multi-Cell MMSE Vector Combining to Reduce Computational Cost for Massive MIMO Systems

A practical partial multi-cell MMSE (PM-MMSE) combining vector for multi-cell massive MIMO systems is proposed in this work. This new scheme uses only inter-cell channels causing strong interference as partial inter-cell information in the multi-cell MMSE approach. The performance of PM-MMSE is evaluated using channels measured in a two-cell outdoor experiment. In addition, a SIR threshold Γ is introduced as a tradeoff parameter between spectral efficiency and computational cost. For multi-cell scenarios, simulation results show that in a system with 16 cells and 320 users, PM-MMSE is capable of achieving 96% of the M-MMSE spectral efficiency using on average a tenth of inter-cell channel information. For this scenario, PM-MMSE requires only 60% of the total number of multiplications used by M-MMSE.