mohammed Alosaimi

Graduation project: signal quality of the communication system (EVM) analysis. Due the significance of the EVM for high-speed optical and wireless communication systems, the estimation of signal’s EVM is performed by using theoretical model and experimental setup in this thesis. For wireless communication systems with QAM modulation, a theoretical model is developed by involving the amplitude imbalances and the phase imbalance of the transmitter and receiver, and the phase noise of the optical link. Thus, a theoretical expression for calculating EVM is derived for describing the impacts of IQ imbalances and phase noise precisely. Next, simulations are performed to obtain EVM for 16-QAM and 32-QAM formats by using specific parameters of imbalances and phase noise. The obtained EVM values are consistent with the results shown in previous reports, with the derived theoretical model being verified. Furthermore, a back to back communication system is built in the laboratory by using a vector signal generator and a signal analyzer. The EVMs for QPSK、16-QAM、64-QAM、128-QAM modulation are measured as 3.01 %, 3.52%, 4.51%, or 5.848%. In summary, a theoretical model for calculating EVM of a communication system with QAM modulation format has been derived, which is then verified in simulations and experiments. This work might be beneficial for system design and performance evaluation of modern communication.