Characterization of the Error Performance of a QPSK (Quadrature Phase Shift Keyed) Communication System in the Presence of Linear Transmission Distortion

摘要

The purpose of this study was to investigate the effects of linear transmission distortion on a Quadrature Phase Shift Keyed communication system and to calculate the probability of error for a given amount of distortion with different signal-to-noise ratios. The baseband QPSK system was designed to eliminate all intersymbol interference that did not result from distortion or additive white gaussian noise. The types of transmission distortion investigated were linear amplitude, linear delay, and quadratic delay distortion. Each type of distortion is discussed and modeled. From a range of signal-to-noise ratios, for the given distortion values, a bit error rate is determined. Two types of bit error rates are used. One is the worst case, upper bound, a pessimistic bound that can not be exceeded. The other, is an average probability of error determined by use of center of mass methods. This method provides a bit error rate that may be exceeded but gives an overall first look at the probability of error for that SNR and distortion type and level. The graphs that resulted allow for quick reference of the bit error rate for a range of SNR's at differing values of linear amplitude, linear delay and quadratic delay distortion. (Thesis)