Approximation error analysis for coherent EGC receiver under Nakagami-m fading channels

The generalized fading amplitude can be expressed using the Nakagami-m distribution. The probability density function (PDF) for the sum of m-distributions is needed to evaluate performance of diversity combining technique such as equal gain combining (EGC) receiver. The approximated PDF for the sum of m-distributions gives simpler performance expression and reduces the computational complexity in evaluating EGC performance. We investigate the normalized approximation error of EGC performance. From the observed result, even for m > 2, the approximated BER is not accurate. For example, the normalized error is about 32% for m = 2 with 3 identical and independently distributed (IID) fading branches and 10 dB SNR.