Diagonal Space Time Block Coded Spatial Modulation

In this paper, a new Spatial Modulation (SM) scheme, called Diagonal Space Time Coded Spatial Modulation (DS-SM), is designed by embedding the Diagonal Space Time Code in SM. The DS-SM scheme still inherits advantages of SM while enjoying further benefits from spatial constellation (SC) designs. Based on rank and determinant criteria, a new set of four SC codewords is proposed for the DS-SM system with 4 transmit antennas to achieve the fourth-order diversity. Then a general design procedure for an even number of transmit antennas, larger than 4, is developed by cyclically shifting two rows of the SC codewords. Simulation results show that DS-SM surpasses several existing SM schemes at the same spectral efficiency and antenna configuration. DS-SM also exhibits better performance over the benchmark systems under spatially correlated channels. Complexity of DS-SM is also analyzed and compared with other SM schemes.