Efficient Parallel PAPR Reduction Method Using Null-Constrained Peak Cancellation Signal for Massive MIMO-OFDM Systems

In this paper, we propose new methods for reducing the peak-to-average power ratio (PAPR) for downlink massive multiple-input multiple-output (MIMO) along with orthogonal frequency division multiplexing. We develop the PAPR reduction method based on peak cancellation (PC) signals using the null space in a MIMO channel, which can prevent in-band distortion at the receiver while reducing the PAPR of the transmitted signal. The proposed method concurrently performs the PC signal-based PAPR reduction process using the small number of transmitter antennas by dividing them into multiple blocks. Although this method leverages the low-dimensional null space in the MIMO channel, it facilitates PAPR reduction while suppressing the degradation of the bit error rate (BER) and reducing the required computational complexity. Furthermore, we introduce the generation of PC signals that suppress the multiple peaks of the original transmitted signal in the time domain, further reducing the computational complexity in the PAPR reduction process. Computer simulation results show that the proposed method significantly reduces the computational complexity and improves the BER and convergence rate of the PAPR.