Design of Spatial Constellation for Spatial Modulation

In order to achieve the transmission of more extra information bits, a new design, called spatial modulation with spatial constellation design (SM-SC), is proposed to extend the size of a spatial constellation diagram in spatial modulation (SM) system by designing the component formation of the transmitted spatial constellation vector (TSV). In our SM-SC, the spatial index bits are made up of two parts: the symbol group index (GI) and antenna index (AI) bits. A AI set of all possible antenna index combinations of active transmit antennas (TAs) is designed for the transmission of AI bits. With the aid of imaginary “ ${j}$ ” sign, a set of the symbol groups (SGs) is designed for the transmission of GI bits. Furthermore, a SG using the GI bits is selected from the SG set, each component of the selected SG is then respectively multiplied with that of a multidimensional data symbol. The resulting in every new component is modulated on the corresponding TA activated by the AI vector, which is selected by the AI bits from the AI set. Moreover, the spatial index bits and squared MED, complexity, the average bit error probability are analyzed. Finally, the results with the simulation and theoretical analyses verify the effectiveness and advantage of SM-SC.