Space-time coded OFDM with low PAPR

Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) systems employing space-time coding have been proposed for providing high-data rate services over wireless channels. These schemes combine the advantages of space-time coding and OFDM, resulting in a spectrally efficient wideband system. However, current MIMO-OFDM systems do not consider the problem of inherent high peak to average power ratio (PAPR). In this paper, we propose a general framework for PAPR reduction for space-time coded OFDM systems. We show that with the new scheme, significantly reduced PAPRs can be obtained at the cost of a slight decrease in the spectral efficiency of the system. In particular, using trellis shaping before space-time coding, examples show that a PAPR reduction of 4.5 dB is possible.