PAPR Reduction Scheme for MISO and MIMO OFDM Systems with Limited Feedback

For multiple-input single-output (MISO) and multiple-input multiple output (MIMO) beamforming (BF) orthogonal frequency division multiplexing (OFDM) systems employing cluster-based codebook index feedback (CCIF), a new peak-to-average power ratio (PAPR) reduction method is proposed. In the proposed method, a dummy signal is generated in null space of the channel and superimposed on the original signal to reduce the PAPR. First, we modify the conventional method to apply to the MISO/MIMO OFDM system with CCIF based BF. From the observation that the conventional method will severely degrade the bit error rate (BER) performance, weight functions for the dummy signal across the subcarriers are proposed. The proposed weight functions are found by both nonlinear optimal and simple suboptimal manners. Through simulation results, it is shown that the proposed scheme can make the BER loss be negligible at the expense of some loss in PAPR reduction gain. Key-Words: OFDM, MIMO, PAPR reduction, transmit beamforming, limited feedback.