Maximal ratio combining in independent identically distributed N*Nakagami fading channels

Short-term fading in wireless systems can be described using a cascaded approach permitting the modelling of severely faded channels. A maximal ratio combining (MRC) diversity is implemented to study the performance improvement in such channels. While the probability density function (pdf) of the signal-to-noise ratio of the independent and identically distributed N*Nakagami cascade channels is available in terms of Meijer's G functions, the pdf of the MRC output is not available. Because of this, the moment generating function of the MRC output is used to estimate the average bit error rates. The characteristic function is used to obtain the cumulative distribution (CDF) of the MRC output by applying the Gil-Pelaez approximation. The outage probabilities were then estimated using the CDF. Results showed that the wireless system performance improved with diversity even though the level of improvement declined as the number of cascaded components N increased. The analysis also suggests that additional mitigation such as combining signals from multiple base stations (macrodiversity) might be necessary to significantly improve the performances of cascaded channels.