Error rate performance of QAM and QPRS systems in adjacent and cochannel interference with frequency selective fading

An analytical technique for evaluating the error rate performance of M-ary quadrature amplitude modulation (QAM) and quadrature partial response signaling (QPRS) in the presence of adjacent channel and cochannel interference with frequency selective fading is developed. Error probability expressions are derived and evaluated numerically using the method of saddle point integration proposed by C. W. Helstrom (1986). In addition to the above impairments, the system model also incorporates other disturbances, namely, stationary white Gaussian noise, quadrature-channel interference, random timing misalignments and carrier phases of interfering signals. An extensive set of results and comparisons is presented