Fading distribution of diversity techniques with correlated channels

Signal fading in mobile radio environments significantly impairs the performance of communication systems. Diversity reception provides redundancy which can be exploited to reduce the impact of fading on bit error rate (BER) performance. Diversity channels are correlated in most practical applications because of non-ideal frequency, time, or space separation. The performance analysis of a communication system becomes complicated under correlated diversity channels. This paper presents a simple means of performance analysis based on fading distributions. Selection diversity and maximal ratio combining diversity techniques are studied. Simple formulas are derived, which can be used to predict the diversity gain of a communication system employing diversity. Performance results for DQPSK as an illustrative modulation technique are included as an example