Aydın, ErdoğanÇögen, FatihBaşar, Ertuğrul2021-01-082021-01-0820190018-95451939-9359http://doi.org/10.1109/TVT.2019.2928378https://hdl.handle.net/20.500.12846/184Basar, Ertugrul/0000-0001-5566-2392; Aydin, Erdogan/0000-0002-5198-0980; Cogen, Fatih/0000-0002-1163-5920WOS:000501349900073In this correspondence paper, a novel code-index modulation (CIM) aided quadrature spatial modulation (QSM) scheme, called CIM-QSM, is proposed for highly spectrum and energy efficient multiple-input multiple-output (MIMO) systems. The CIM-QSM scheme transmits information over three different transmit entities: modulated symbols, activated antenna indices, and spreading code indices. Hence, a higher efficiency in terms spectrum and energy use, and better error performance compared to the conventional direct sequence spread spectrum, spatial modulation (SM), QSM, and CIM aided SS (CIM-SS) schemes are obtained by the CIM-QSM technique for MIMO communication systems. Analytical expressions for the average bit error rate, energy efficiency, and throughput of the CIM-QSM system are performed and the theoretical results are validated with Monte Carlo simulation results.eninfo:eu-repo/semantics/closedAccessModulationReceiversMimo CommunicationIndexesTransmitting AntennasDetectorsQuadrature Spatial ModulationCode Index ModulationMimo SystemsAnd Direct Sequence Spread SpectrumArticle681010.1109/TVT.2019.29283781025710261Q1Q1WOS:0005013499000732-s2.0-85073877804