Using moment generating function (MGF) of generalized selection combining (GSC) output signal-to-noise ratio (SNR), we derive closed-form expressions for average combined SNR at the output of GSC, which optimally combines the N largest out of L available diversity signals, over Nakagami-m fading channels for N = 2, 3 and L = 4. The Nakagami-m fading statistics on each diversity branch are assumed to be independent and identically distributed (i.i.d.). The average combined SNRs at the outputs of GSC receivers are also compared with the average combined SNRs at the outputs of conventional maximal ratio combining (MRC) and selection combining (SC).

This paper investigates the asymptotic error rate behaviour for noncoherent OOK signalling scheme in the presence of Nakagami-m fading. A transcendental equation to compute the optimum threshold level is also derived. Comparison on trends in optimum threshold level and its corresponding ratio of the Mark and Space error probabilities between different channels are presented.