Papr Reduction for Beamforming Ofdm Transmitters

A high peak-to-average-power ratio (PAPR) is a primary drawback of orthogonal frequency-division multiplexing (OFDM). Many methods have been proposed to reduce the OFDM PAPR for single-antenna and for MIMO systems. Some systems, however, use multiple antennas for frequency-selective transmit beamforming either to a single or multiple simultaneous receivers. This paper presents a new method for PAPR reduction that minimizes the peak power across all antennas while preserving the maximal ratio transmission (MRT) gain and zero-crosstalk criteria at the receivers. Because the gain and zero crosstalk is preserved at the receivers, no performance loss is seen by the receivers when using the PAPR-reduced transmit vector. With eight transmit antennas, the algorithm demonstrates an average of 5.5 dB PAPR reduction for single-user beamforming and about 4.5 dB PAPR reduction for four-user transmit spatial division multiple access (Tx-SDMA)