Performance analysis of multiple-antenna systems in correlated fading channels: from measurements to analysis

Abstract

Wireless communications equipped with multiple antenna technology (multiple-input multiple-output, MIMO) have emerged as one of the most promising techniques due to the great potential to improve the system reliability and capacity. Spatial multiplexing (SM) gain increases a data rate, while diversity gain improves link reliability.

The minimum mean square error (MMSE) receiver for SM systems can be used instead of zero forcing (ZF) since the MMSE receiver provides better performance than the ZF by mitigating both interference and noise. For the uncorrelated Rayleigh channels, the exact probability density function (PDF) of the signal-to-noise ratio (SNR) and bit error rate (BER) expression were derived for MIMO ZF receivers. The PDF of the signal-to-interference-plus-noise ratio (SINR) and symbol error rate (SER) approximation for MIMO MMSE receivers in the uncorrelated Rayleigh channels were derived for a small number of transmitting (Tx) and receiving (Rx) antennas. For the transmit-correlated Rayleigh channels, the SNR after ZF receivers was shown as a Gamma distribution, which was used to obtain the BER approximations. For the transmit-correlated or receive-correlated Rayleigh channels, it was found that the SINR for the MMSE receivers approaches a Gamma or a generalized Gamma. Using both distributions, the approximated SERs were analyzed. However, these results showed the limits on accuracy imposed by the approximated distributions.

When channel state information (CSI) is available at both the transmitter and receiver, the diversity can be obtained by MIMO transmit beamforming with maximal ratio combining (MRC) receivers. The analytical performance results of MIMO-MRC, such as the SER and outage probability, have been derived based on the maximum eigenvalue statistics of Wishart matrices. Recently, double-correlated (referred to as \emph{Kronecker model}) Rayleigh fading was considered. However, it was shown that, since the Kronecker mo...