Bi-space shift keying (BiSSK) can increase the spectral efficiency of space shift keying (SSK) but requiring a large number of available transmit antennas. A new SSK-based modulation scheme is proposed which requires a smaller number of transmit antennas than what required in BiSSK to deliver the same transmission rate at a negligible performance loss. The proposed scheme is obtained by multiplexing two in-phase and quadrature generalized SSK (GSSK) streams and optimizing the carrier signals transmitted by the activated antennas. Performance of the proposed scheme is compared with other SSK-based schemes via minimum Euclidean distance analysis and computer simulation.
