Variable active antenna spatial modulation

In this study, variable active antenna spatial modulation (VASM) technique, which allows the selection of any number of antennas (but not a constant number of active antennas) to transmit a symbol at the same signalling interval, is presented. In the first step of the development of VASM, antenna selection method is determined to use the minimum number of transmit antennas. Complexity analysis of maximum likelihood decoder is given for the new scheme. In the second step, to reduce the correlation effect, a novel antenna selection method called VASM improved (VASMi) that minimises the pairwise error probability is introduced for exponentially correlated channels. For 6, 8, and 10 bit/s/Hz spectral efficiencies, bit error rates are obtained and compared with spatial modulation (SM) and generalised SM (GSM) for different antenna and signal constellation configurations. VASMi outperforms SM and GSM in both uncorrelated and exponentially correlated multiple-input multiple-output channels for similar antenna configurations.