COMPUTING ERROR PROBABILITIES OVER FADING CHANNELS - A UNIFIED APPROACH

This paper is a tutorial on the calculation of error probabilities for fading channels. The method we advocate is centered on the evaluation of the Laplace transform Phi(Delta)(s) of the probability density fun ction of the difference Delta between the metrics of two competing sig nal sequences. In some cases, knowledge of the function Phi(Delta)(s) allows one to determine error probabilities exactly in closed form, or asymptotically as the signal-to-noise ratio grows to infinity. The ge neral technique that we describe here allows their computation in nume rical form to any desired degree of accuracy. Coded as well as uncoded transmission can be considered in this unified framework. For illustr ation's sake. some examples of calculations are provided for frequency -flat slow-fading channels in which coherent detection is used, and th e channel state information is perfect, or unavailable, or obtained fr om a noisy pilot tone.