Interference mitigation for distributed MIMO cellular systems using cooperative beamforming

Abstract

Distributed antenna systems (DAS) reduce the access distance for users in areas away from the cell center, thereby, enhancing the transmission capability for those users. Recent studies have shown that antenna selection transmission (AST) is preferable to maximum ratio transmission (MRT) in a multicell DAS environment, owing to its interference reduction. However, it is obvious that users still suffer from strong interference at the cell edge when applying universal frequency reuse in DAS. We propose an efficient cooperative beamforming transmission (CBT) algorithm, whose basic idea is taking the distributed transmitting antennas within a cell and receiving antennas including desired users and adjacent cells' interfered users, as a distributed multiple-input multiple-output (D-MIMO) channel, by which CBT mitigates the interference through joint precoding. We analyze the proposed algorithm mathematically and compare it with other existing algorithms. A Monte-Carlo simulation is also carried out to verify the derivation. Both the analysis and simulation results show that the CBT algorithm outperforms both AST and MRT especially near the cell edge.