16-QAM modulation type is used and root-raised cosine pulse shaping filters are implemented

摘要

In this paper a simulation of a wireless digital communication system is presented. The purpose of this work is to demonstrate important components of digital communication systems and how their presence impacts system behaviour. The simulations for this project were carried out using MATLAB. The modeled system is a frequency flat channel and the transmitted data is subject to AWGN, Rayleigh fading, and phase errors. A 16-QAM modulation type is used and root-raised cosine pulse shaping filters are implemented. This report also presents techniques to mitigate channel effects. These include phase estimation/correction algorithms and receiver diversity through the use of multiple receiver antennas. Simulation results demonstrate the effect of the SNR on several parameters including the received signal constellation as well as the BER for AWGN and Rayleigh channels. These simulation results are shown to be in agreement with the theoretical (expected) results. Simulations also show that small phase errors can led to a large degradation in system performance. The implemented phase estimator/corrector helps mitigate these effects for both AWGN and Rayleigh fading channels. BER improvements occur when receiver diversity is implemented Using a maximal ratio combiner. This improvement in performance is demonstrated by simulating a system with one, two, and four receive antennas. Investigations of the power spectral density of the root-raised cosine filter as a function of the roll-off factor are also discussed.