Computer-Aided Analysis of Interference and Intermodulation Distortion in FDMA Data Transmission Systems

Abstract

Multi-carrier FDMA methods are widely used for transmitting digital data from several sources. In some cases, the digital signals may be controlled by a single clock and hence, the data channels may be fully synchronized. This paper describes a method for evaluating the characteristics of adjacent Channel interference (ACI), and intermodulation (IM) distortion in a FDMA data transmission system with synchronous data streams. A computer simulation method is used to evaluate the statistical characteristics of ACI and IM. It is shown that the IM component is uncorrelated with signal components whether or not the data streams are synchronous. The distribution of the IM amplitude is shown to be Gaussian and hence, the IM can be treated as an additive Gaussian noise component. ACI in multichannel FDMA data transmission systems is also shown to exhibit similar characteristics.