Antenna Doping: A Countermeasure Against MIMO Spatial Correlation

In this paper, we address the problem of multiple-input multiple-output (MIMO) spatial multiplexing (SM) systems in the presence of antenna fading correlation. It is well known that severe spatial correlations present at the transmitter and/or receiver can significantly compromise the performance of existing SM systems. Recent results showed that joint-over-antenna (JA) iterative detection schemes can improve the performance of SM systems in correlated channels as compared to schemes that detected the signals on an antenna-by-antenna basis. We extend this idea in this paper by incorporating a so-called antenna doping (AD) scheme into the SM system, in order to further counteract the detrimental effects of spatial correlation. Through simulations, we show that AD can improve the performance by 3-4 dB in severe spatial correlation as compared to non-doping systems. This improvement is explained with the aid of extrinsic information transfer (EXIT) charts, which illustrate the convergence behavior of the JA iterative detection with and without AD.