Antenna selection techniques for large-scale MIMOAntenna selection techniques for large-scale MIMOΤεχνικές επιλογής κεραιών σε μεγάλα συστήματα MIMO Διπλωματική Εργασία Diploma Work 2019-02-212018enThe recent concept of large-scale multiple-input multiple-output (MIMO) systems has attracted substantial research attention and been regarded as a promising technique for next-generation wireless communications networks. Combined with the cost of analog radio-frequency chains it necessitates to work on the use of efficient antenna selection (AS) schemes. Signal-to-noise ratio (SNR) optimal transmit antenna selection and beamforming for a MIMO system that consists of a large number of transmit antennas has been considered in this work. We examine an algorithm that has polynomial complexity and solves the transmit AS problem for maximum-SNR joint beamforming with two receive antennas and under a total power constraint. Furthermore, this thesis works on the beamforming vector approximation under a per-antenna-element power constraint on the transmitter, a problem which has not been efficiently solved so far and many suboptimal algorithms have been produced to tackle this problem. Some of them are examined and compared in this thesis.http://creativecommons.org/licenses/by/4.0/Πολυτεχνείο Κρήτης::Σχολή Ηλεκτρολόγων Μηχανικών και Μηχανικών ΥπολογιστώνPapaioannou_Dimitrios_Dip_2018.pdfChania [Greece]Library of TUC2019-02-21application/pdf592.5 kBfree Papaioannou Dimitrios Παπαϊωαννου Δημητριος Karystinos Georgios Καρυστινος Γεωργιος Liavas Athanasios Λιαβας Αθανασιος Bletsas Aggelos Μπλετσας Αγγελος Πολυτεχνείο Κρήτης Technical University of Crete Antenna selection ΜΙΜΟ systems Beamforming