New PAPR reduction method for spatial modulation using an unitary precoder

In this paper, a new peak-to-average power ratio reduction method for spatial modulation is presented. This is done by multiplying an unitary precoder to modulated signals so that total transmit energy is uniformly scattered into all transmit antennas. When using an ideal amplifier, the proposed method guarantees performance identical with the conventional scheme due to the orthogonality of the precoder with almost same decoding complexity. When using a nonideal amplifier, the proposed method is shown to exhibit significant performance improvement, especially, for high input-back-off and a large number of antennas.