Error Probability of Energy Detected Multilevel PAM Signals in Lognormal Multipath Fading Channels

Noncoherent multilevel systems have been typically analyzed with spectrally inefficient orthogonal modulation methods. In this paper, we present a novel error probability analysis of energy detected (ED) signals with spectrally efficient multilevel pulse amplitude modulation (PAM). One of the main challenges in the analysis of ED systems with the multilevel PAM is to find analytical methods to evaluate and optimize the performance of ED systems with respect to arbitrary system parameters, e.g., decision thresholds for chi-squared-distributed decision variables, integration time, bandwidth, and number of modulation levels. We propose analytically tractable methods that can be efficiently used to design spectrally efficient ED systems for short-range, wideband, and high data rate wireless communications in lognormal multipath fading channels with uncorrelated diversity paths.