Abstract In this paper we determine the probability of error of a predetection generalized selection combining (GSC) receiver with correlated and unbalanced diversity branches in a Nakagami‐m multipath fading channel. We start by finding the joint probability density function (PDF) of the decision variables. This involves the derivation of the joint PDF of the L largest random variables (L maxima) of an input population of N > L correlated nonidentically distributed random variables, based on the statistics of the input population. The results obtained are then used in the derivation of the error probabilities of noncoherent FSK (NCFSK) and DPSK receivers. Copyright © 2006 John Wiley & Sons, Ltd.

Degradation in carrier-to-interference ratio (CIR) due to optical beat interference (OBI) in subcarrier multiplexed wavelength division multiple Access (SCM/WDMA) networks using direct photodetection is evaluated. The subcarriers are assumed to directly intensity modulate separate lasers. A large signal model for the modulated laser light is used. The discrepancy in CIR between this model and the small signal model commonly used in the literature is important at high modulation indices (4.5 dB at about unity modulation index). This justifies the introduction of the large signal model for analyzing OBI. It is found from analytical results that OBI is lower for higher intensity modulation indices.>