MultiMode Generalized SpaceTime Index Modulation: A HighRate Index Modulation Scheme for MIMOISI Channels In this paper, a new index modulation technique, referred to as the multimode generalized spacetime index modulation (MMGSTIM) is presented. MMGSTIM is a highrate index modulation scheme for multiantenna intersymbol interference (MIMOISI) channels. The proposed MMGSTIM is a single carrier scheme with zero padding (ZP). MMGSTIM performs xe2x80x98modeindexingxe2x80x99 to efficiently increase the spectral efficiency. In a given MMGSTIM frame, disjoint subsets of spacetime slots are used to transmit modulation symbols from disjoint modulation alphabets (referred to as the modes). The choice of which spacetime slots are used for transmission of a particular mode in an MMGSTIM matrix conveys information bits. Thus, MMGSTIM is a generalization of the wellknown index modulation schemes such as spatial modulation (SM), generalized spatial modulation (GSM), and spacetime index modulation. Here, an analytical characterization of the diversity order of the proposed MMGSTIM scheme and the conditions required to maximize the transmission rate of multimode index modulation schemes are derived. Through simulations, it is shown that the proposed MMGSTIM scheme can achieve better performance compared to other modulation schemes in MIMOISI channels.

LowComplexity Multiuser Detection for Generalized MediaBased Modulation Systems Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057, China In this paper, we consider multiuser generalized mediabased modulation (GMBM) system, where the users adopt both generalized spatial modulation (GSM) and mediabased modulation (MBM) schemes to convey extra information via antenna and RF mirror indices. The GSM scheme activates only a subset of available antennas for transmission, and the MBM scheme uses the onoff state of RF mirrors placed around the antennas to create different channel realizations. GMBM improves spectral efficiency for transmission with limited RF resources. We propose two structured compressivesensing algorithms to detect multiuser signals with low complexity. Three types of structure, i.e. the users, the antennas, and the RF mirrors, are recovered during each iteration of the algorithms. The structured subspace pursuit (SP) algorithm for MUGMBM is shown to have better performance for various system settings, and both algorithms benefit from the increase in receive diversity.