Spatial Modulation Using Signal Space Diversity

In this letter, a novel scheme, called spatial modulation (SM) using signal space diversity (SM-SSD), is proposed for future multiple-input multiple-output (MIMO) systems. In this scheme, consecutive time slots are modulated jointly, and the technique of signal and space diversity (SSD) is applied to spread the real and imaginary parts of data symbols over the time domain. In addition, novel active antenna activation pattern and time activation pattern selection algorithms are introduced. An upper bound expression for bit error rate (BER) is obtained and a diversity analysis is performed. Besides, a suboptimal solution for the optimization of rotation angles is put forward to maximize the minimum coding gain distance (MCGD). Monte Carlo simulations are performed to compare the BER performance of SM-SSD with the benchmark schemes, in the presence of both correlated and uncorrelated channels. Lastly, the change in the spectral efficiency is analyzed for different numbers of time slots and transmit antennas.