Transmit diversity with single RF front-end using CIOD

Complex interleaved orthogonal design (CIOD) can offers diversity gain to the part of the source in spatial modulation which has single radio frequency (RF) front-end at the transmitter despite multiple-input multiple-output, but emits the undesired component out-of-band. For the reducing out-of-band emission, we give up indicating the information source by the antenna switching and increase both the interleaver size and the antenna switching interval. The increase reduces the discontinuities in the waveform and out-of-band emission. We propose such a scheme as transmit diversity with single RF front-end using CIOD. The diversity gain of the proposed scheme is equivalent to the case for CIOD. Moreover, we evaluate the increase of out-of-band emission and confirm that of the proposed scheme compared to the ideal case is only 3 dB.