In distributed antenna systems (DAS), multi-user interference was shown to be asynchronous, which had not been paid much attention. In this study, the authors compare the performances of the DAS under the condition of asynchronous interference (AI) with four well-known multiple-input multiple-output (MIMO) algorithms namely zero-forcing (ZF), block diagonalisation (BD), signal-to-leakage-plus-noise ratio (SLNR) and dirty paper coding (DPC) algorithms. The simulation results clearly demonstrate significant performance degradations of these algorithms. To further improve the performance under the condition of AI, this study presents an improved BD algorithm and a significant improvement is shown through corresponding simulation results. © 2012 The Institution of Engineering and Technology.