The dissertation thesis deals with a study of an influence of a simultaneous incidence of an additive thermal noise and a multiplicative phase noise on the useful signal transmission in narrowband satellite communication systems. While the additive thermal noise affects the useful signal only on the receiver side of the communication system, the multiplicative phase noise is produced in all system oscillators. One investigates how the receiver filter bandwidth reduction takes effect on the influence of individual noise types. The thesis is divided into four units. The first one (chapters 4 and 5) solves the ways of modeling of both noise types. In the second part (chapter 6), on the simple example, the primary analysis of the phase noise influence is made. Basic modulation schemes used in the satellite communication are also discussed (chapter 7). Third part (chapter 8) is devoted to the modeling of a general digital system with a M PSK modulation made directly on the main carrier wave. The last part (chapter 9) describes the modeling of a digital system with a BPSK modulation on the auxiliary subcarrier wave followed by an SSB modulation on the main carrier wave. General conclusions are deduced from obtained simulation results.

[pt] Para suportar os requisitos das redes móveis de 5a geração (5G), os sistemas de comunicação óptica serão usados nas redes de acesso. Isso ocorre porque a evolução das RAN (Radio Access Networks) incluem a centralização do equipamento mais crítico para implantar pontos de acesso móveis de baixa potência, como DAS (Distributed Antenna Systems) e Small Cells. Os serviços emergentes solicitam a implantação de tecnologias de rádio sobre fibra com ênfase na eficiência de largura de banda, eficiência energética e alta confiabilidade. Neste âmbito, um monitoramento eficiente da camada física é imperativo para a operação dessas redes. O sistema de monitoramento deve fornecer uma localização de falhas em serviço, econômico, centralizado e com impacto mínimo para a transmissão de dados. Esta tese propõe vários sistemas de monitoramento incorporado no transceptor utilizando reflectometria óptica no domínio do tempo. Os sistemas de monitoramento são testados em diferentes sistemas de transmissão de dados e arquiteturas de rede, onde é apresentada uma validação simulada e outras experimentais. / [en] In order to support the requirements for 5th generation mobile networks (5G), optical communication systems will be used in the access part of the network. This is because the evolution of radio access networks includes the centralization of the most critical equipment in order to deploy low power mobile access points, like distributed antenna systems and small cells. The emerging services call for the deployment of radio over fibre technologies with emphasis on bandwidth efficiency, energy efficiency and high reliability. Within this scope, an efficient monitoring of the physical layer would become essential for the operation of these networks. The monitoring system should provide in-service, cost efficient and centralized fault localization with minimum impact on data transmission. This thesis proposes several transceiver-embedded optical time domain reflectometry monitoring systems. The monitoring systems are tested over different data transmission systems and network architectures, where one architecture was simulated and several others experimentally validated.