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Underwater acoustic channel models have been studied in the context of communication and sonar applications. Acoustic propagation channel in an underwater environment exhibits multipath, time-variability and Doppler eects. In this thesis, multipath fading channel models, underwater physical properties and sound propagation characteristics are studied. An underwater channel model for sonar applications is proposed. In the proposed model, the physical characteristics of underwater environment are considered in a comprehensive manner. Experiments /simulations were carried out using real-life data. Model parameters are estimated for a specific location, scenario and physical conditions. The channel response is approximated by fitting the model output to the recorded data. The optimization and estimation are conducted in frequency domain using Mean Square Error criterion.

The paper deals with the channel coding and modulation in DVB-H and DVB-SH and with the simulation of the components in MATLAB. In the case of DVB-H the document also discuss the influence of different types of transmission channels on the transmission process. The first part of this work describes the channel coding and inner modulation in DVB-H and DVB-SH. The next part describes applications created in MATLAB for settings and simulation of the transmission in the standards DVB-H and DVB-SH. The last part of this document graphically presents selected results of the simulation of the transmission and discuss them.

The diploma thesis Simulation of Multipath Propagation of Multistate Modulations is focused on the development of an appropriate algorithm in MATLAB environment, which is capable to simulate the impact of the multipath propagation on received signal (error rate) on the basis of given parameters of the transmission channels. Mechanisms and characteristics of the wave propagation in communication environment, types of digital modulations and their most important parameters are described in the first part of this thesis. The second part is focused on the simulation itself. Created GUI (Graphical User Interface) is able to display constellation diagrams of transmitted and received signals, as well as their bit error rate. It is also possible to compare these data with the data of signal, which is passed by a non-fading channel.