Robust MMSE Precoding for Out-of-Cluster Interference Mitigation in Cell-Free MIMO Networks

Abstract

In this work, we develop a linear robust minimum mean-square error (RMMSE) precoder to mitigate the effects of imperfect channel state information (CSI) and the intra-cluster (ICL) and out-of-cluster (OCL) interference in cell-free (CF) multiple-antenna systems. The proposed precoder includes statistical information of the OCL interference in its derivation, allowing a more effective interference mitigation. An analysis of the sum-rate that can be obtained by the CF system is carried out and an expression quantifying the theoretical gains of mitigating OCL interference are derived. Simulation results corroborate that the proposed RMMSE precoder effectively mitigates ICL and OCL interference.

Figures (2)

• Figure 1: Power of the OCL interference considering different mitigation schemes.
• Figure 2: ESR performance of the precoders with different OCL interference mitigation schemes