The Estimation Problem in Null-zone Reception Feedback Systems

Résumé du livre

Null-zone-reception decision-feedback systems are shown to work almost as well when statistical estimation must be used to determine the threshold settings as when channel conditions are known exactly. This conclusion cannot, of course, encompass all possible channel models, but is based on careful investigation of a synchronous binary symmetric phase-shift system with gaussian noise, plus briefer examination of two envelopedetection systems. An estimation procedure which is optimum, under certain assumptions, is presented, but this is not, in general, computationally feasible. Two non-optimum procedures which are simple and practicable are presented, however, one based on a power measurement method and the other on an average magnitude approach, and both are shown to yield good results, the latter being somewhat superior. When signalstrength correlation is appreciable over as few as ten digits, overall system performance is only slightly less efficient than would be attained with exact knowledge of the channel conditions. Methods of minimizing the undesirable effects of impulsive and burst-type noise are discussed. (Author).