On the Characterization of Noise in the Simulation of Nonlinear Wideband Satellite Digital Links

Abstract

The prediction of performance (BER) for a digital satellite link possessing typical impairments is a difficult analytical undertaking. When, further, the repeater is nonlinear and the uplink noise is nonnegligible, the difficulty of an analytical approach is greatly compounded. Consequently simulation is becoming increasingly common as a tool for solving the BER-prediction problem. It is often assumed, however, that a link is characterized by a single Gaussian noise source at the receiver. This assumption can lead to considerable error in the weak uplink nonlinear system. For the latter situation we consider in this paper the problem of characterizing an equivalent single noise source at the receiver, which will better account for actual system behavior than the Gaussian source. For this equivalent source we postulate that the pdf is drawn from a family of the form const x exp [ - | x | v] and obtain through simulation the BER performance as a function of v. Comparing these results with Monte Carlo simulation runs shows the possibility of approximately characterizing the complex system's behavior by a single non-Gaussian noise source.