Peak-to-Average Power Ratio Reduction in MIMO OFDM

Peak-to-average power ratio (PAR) reduction in OFDM using antenna arrays (MIMO OFDM) is considered. In particular, generalizations of selected mapping (SLM) recently proposed in literature, are studied, and a new version, we call it directed SLM (dSLM), is introduced. It is shown that, in contrast to the other schemes, dSLM utilizes the potential offered by MIMO transmission-the complementary distribution function of the PAR exhibits a steeper (increased by a factor equal to the number of transmit antennas) decay. This effect is similar to the diversity gain in error performance when using MIMO transmission. We show that dSLM is very flexible and not restricted to any modulation format or OFDM frame size. Moreover, a variant of dSLM which does not require any side information to recover data at the receiver is presented.