Pre-processing based advanced spatial modulation techniques

Spatial Modulation (SM) extends the concept of index modulation into the spatial domain, forming a specialized type of multiple-input multiple-output (MIMO) architecture. Inspired by the advantages of the SM, this thesis deals with systems that utilize different forms of advanced SM. Each of these systems is designed with a specific purpose, among these objectives are robustness to channel and antenna correlations, reliability, energy efficiency and improved bit error rate (BER) performance. This thesis proposes different communication systems employing advanced SM techniques in six chapters as the following: i) a precoding strategy for quadrature spatial modulation (QSM), aiming to enhance robustness against the effects of Rayleigh/Rician fading and spatial correlations among the transmit antennas, ii) a dual-polarized (DP) QSM scheme and a precoding approach to make the system more robust against spatial correlation and channel fading effects, iii) the joint use of DP antennas and of active antenna dependent signature constellations, to improve performance in terms of robustness to transmit antenna correlation, particularly for Rician fading channels, iv) a novel precoding technique to address the correlation issue for multi-stream SM (MSM) in which multiple antennas are active at a time, v) an innovative backscatter communication (BC) system design based on tag-side pre-processing aided receive spatial modulation (PSM), involving zero-forcing (ZF) and minimum mean squared-error (MMSE) precoders to achieve reduced complexity, enhanced energy efficiency and superior BER performance, vi) a reconfigurable intelligent surfaces (RIS) assisted tag-side PSM based BC system is introduced to make control of the signal propagation, reception and transmission. This achieves better BER performance and energy efficiency in comparison to conventional benchmark approaches. In all proposed architectures, the BER performances are derived analytically, which are confirmed by simulations.