Performance Enhancement of Space-Time MIMO Wireless System using Optimum Decision Algorithm

In this paper, an optimum weight scheme based on Bayes decision rule is adopted in a 2-by-2 Space-Time block code (STBC) multiple-input multiple-output (MIMO) wireless system. The decision algorithm is capable of adjusting the weight vector to optimize the channel covariance, which allows receiver using a linear processing in Alamouti's 2-branch maximum likelihood detection (MLD) without increasing hardware complexity. Analytical expression shows that our proposed scheme provides system performance improvement which was also demonstrated in our BER simulation results under frequency-flat fading channel, especially in the presence of spatial correlation across antennas and maximum Doppler frequency. The channel analysis is also presented that the cumulative distribution functions (cdf) of the eigenvalues generated with the proposed scheme is considerably better than that of the original one (without optimum weight).