Μελέτη χωρητικότητας συστημάτων πολλαπλών εισόδων-πολλαπλών εξόδων (ΜΙΜΟ)
The purpose of this thesis was the theoretical study and simulation of single – user MIMO systems, focusing on the capacity that can be achieved with those systems and on the parameters that influence it. The multiple input – multiple output systems form a recent research field in the wireless communications section. The basic characteristic of those systems is the use of more than one antennas in the transmitter and the receiver. This fact provides improvement in performance measures such as reliability and capacity. Firstly, we referred to the basic propagation mechanisms in a wireless channel and we introduced MIMO systems. Then, we presented in a supervisory way the system categories SISO, SIMO, MISO and MIMO, proving analytically the capacity expression in every one of these categories. In the following, we covered the basic theoretical background of MIMO systems and we estimated the capacity in both Rayleigh and Rician channels. Moreover, we investigated the influence of frequency selective channels and spatial correlation in capacity. Finally, we introduced the virtual channel representation technique and we applied this technique to the estimation of MIMO capacity.