  Reconfigurable intelligent surface (RIS) enhances signal quality by adjusting
the phase of electromagnetic waves in wireless communication. Spatial
modulation (SM), a prominent index modulation (IM) technique, provides high
spectral efficiency and low energy consumption. In this article, a new wireless
communication system is proposed by combining capacity-optimized antenna
selection (COAS), antenna correlation antenna selection (ACAS), and Euclidean
distance-optimized antenna selection (EDAS)-supported RIS-empowered receive SM
(RIS-RSM) system (AS-RIS-RSM) in a single-input multiple-output (SIMO)
structure. The proposed AS-RIS-RSM schemes (COAS-RIS-RSM, ACAS-RIS-RSM, and
EDAS-RIS-RSM) have superior features such as high spectral efficiency, high
energy efficiency, and low error data transmission. Integrating COAS, ACAS, and
EDAS techniques into the system enables the selection of the channel with the
best conditions, thus increasing the error performance of the proposed system.
Also, using RIS increases the error performance of the system by controlling
the transmitted signal to a certain extent. The analytical ABER results of the
proposed AS-RIS-RSM systems are derived and shown to overlap with simulation
results. For the proposed systems, an optimal maximum likelihood (ML) detector
and a sub-optimal low-complexity greedy detector (GD) are offered. Also,
capacity analyses of the proposed AS-RIS-RSM systems are derived and it is
observed that they have higher capacity compared to RIS-QAM/PSK and RIS-RSM
systems. Then, computational complexity analyses of the proposed COAS-RIS-RSM,
ACAS-RIS-RSM, and EDAS-RIS-RSM systems are presented. The proposed systems have
been compared to counterpart wireless communication systems including RIS-RSM,
RIS-QAM, and RIS-PSK under equivalent conditions, demonstrating that the
proposed systems achieve better error performance.
