Mathematical description and formalization types of distortion in a digital communication channel with OFDM-signals

Abstract

Introduction. OFDM technology is widely used in digital television, broadcasting and communication systems. The biggest OFDM advantage is its high spectral efficiency. But the high spectral efficiency needs high-quality synchronization. That is why it is important to analyze received signals distortions appearing because of timing inaccuracy in order to create their compensation algorithms.Mathematical analysis of distortions as a result of uncoordinated timing parameters. Using Fourier transformations properties, the expression for calculation of displacement effect and phase shift of carrier frequency, displacement of timing frequency on the informational signal in the frequency region were acquired. With the help of computer, acquired expressions were simulated and the influence of different uncoordinations on the modulation constellations for the standards of digital video systems ISDB-T were shown.Conclusion. As is seen from the modelling results, inessential inaccuracies at the synchronization cause quite critical distortions that as a result significantly worsen bit error rate. The acquired results let us estimate validity of operation of distortion compensation algorithms as a result of inaccurate synchronization in the process of system development or its verification.