On the benefits of decorrelation in dual-branch diversity

The performance of a dual-branch decorrelator receiver operating in correlated Rayleigh and Rician fading channels in conjunction with selection combining (SC), square-law combining (SLC) and equal gain combining (EGC) diversity is analyzed and compared to the performance of a conventional SC, SLC and EGC diversity receiver. Analytical expressions for the average symbol error rate (SER) and the average bit error rate (BER) of several modulation techniques of practical interest, the mean output signal-to-noise ratio (SNR) and the outage probability are derived. It is shown that the decorrelator receiver has superior performance over the conventional receiver by as much as 2.1 dB in average SNR when SC is employed. Interestingly, it is also shown that the mean output SNR of the decorrelator SC receiver improves with increasing the correlation coefficient while that of the conventional SC receiver degrades with increasing the correlation coefficient. In Rician fading, the results indicate that the outage probability of the decorrelator receiver is much less than the outage probability of the conventional receiver and the gap between the two increases as the channels become less faded.