Time Successive SSK-MPSK: A System Model to Achieve Transmit Diversity

In this letter, we consider an N
_r
× N
_t
multiple-input-multiple-output system in which M-ary phase shift keying (MPSK) and space shift keying (SSK) are used in successive time slots. We call this system time successive SSK-MPSK (TSSM), and we show that this system achieves a transmit diversity order of 2. In TSSM, during the first time slot, information is transmitted with MPSK symbols using all Nt transmitter antennas, with each antenna using Nth t of the total transmitter power. During the second time slot, SSK modulation is used to transmit the same information. We further derive the optimal detection criterion, pairwise error probability, and the average union bound of the bit error rate (BER) of TSSM. We show the diversity order using asymptotic approximation of the average union bound of the BER of TSSM. We compare the BER of TSSM with that of time orthogonal signal design assisted SSK, coherent space time shift keying, and other schemes. The simulation results show that TSSM performs considerably better.